| 1. |
- Maity, Jyoti Prakash, et al.
(author)
-
Furfural removal from water by bioremediation process by indigenous Pseudomonas putida (OSBH3) and Pseudomonas aeruginosa (OSBH4) using novel suphala media : An optimization for field application
- 2023
-
In: GROUNDWATER FOR SUSTAINABLE DEVELOPMENT. - : Elsevier BV. - 2352-801X. ; 20, s. 100895-
-
Journal article (peer-reviewed)abstract
- The release of furfural as effluent from industries has been considered a major pollution source since it adversely affects health and the environment. In a proper nutrient condition, the indigenous microbial removal process is always considered efficient, economical, and eco-friendly. Thus, the main objective is to employ the effective indigenous bacteria to remove the furfural from wastewater. In the present study, the indigenous isolates OSBH3 (strain number) and OSBH4 (strain number) were isolated from furfural-containing-oily-sludge and were iden-tified by 16S-rRNA technique with >99% nucleotide similarity as Pseudomonas putida (P. putida) (Acc. No. GU329915) and Pseudomonas aeruginosa (P. aeruginosa) (Acc. No. GU329916) respectively. In a batch experi-ment, the furfural degradation was observed higher in the presence of the most efficient isolate P. putida (compare to P. aeruginosa) at different nutrient conditions including Suphala (Nitrogen-Phosphorous-fertilizer), glucose, and carbohydrate-free synthetic media (CFM). Generally, the furfural degradation rate was lower in CFM than the other substrates (Nitrogen-Phosphorous-fertilizer/glucose), in the presence of P. putida or P. aeruginosa. The furfural degradation efficiency was observed higher in presence of P. putida, compare to P. aeruginosa. Experimentally, the total (100%) degradation of furfural (500 mg/L) was noticed by P. Putida within 12h incubation time in presence of 1 mg/L Suphala. Even among different factors (based on 'Taguchi L9 orthogonal array study'), the suphala (Nitrogen-Phosphorous-fertilizer) was influential in degrading the furfural at level 2, where the effects of pH and glucose were noticed at level 2 and level 2, respectively. The experimental findings supported the orthogonal array study positively. The bacterial (P. putida) growth rate and furfural degradation were promoted at the condition of 1 mg/L suphala, 2 mg/L glucose (pH 7.2), where the furfural was used by P. putida as the sole-carbon-source for growth. Thus, the indigenous P. putida (OSBH3; Acc. No. GU329915) (in presence of modified nitrogen-phosphorous-fertilizer media), can be applicable for furfural (Toxic) remediation from industrial effluent water by the eco-friendly process.
|
|
| 2. |
- Almeida, Roseley, et al.
(author)
-
Theoretical Evidence behind Bifunctional Catalytic Activity in Pristine and Functionalized Al2C Monolayers
- 2018
-
In: ChemPhysChem. - : Wiley-VCH Verlagsgesellschaft. - 1439-4235 .- 1439-7641. ; 19:1, s. 148-152
-
Journal article (peer-reviewed)abstract
- First principles electronic structure calculations based on the density functional theory (DFT) framework are performed to investigate hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) on two-dimensional Al2C monolayers. In addition to the pristine Al2C monolayer, monolayers doped with Nitrogen (N), Phosphorous (P), Boron (B), and Sulphur (S) are also investigated. After determining the individual adsorption energy of hydrogen and oxygen on the different functionalized Al2C monolayers, the adsorption free energies are predicted for each of the functionalized monolayers in order to assess their suitability for HER or OER. The density of states and optical absorption spectra calculations along with the work function of the functionalized Al2C monolayers enable us to gain a profound understanding of the electronic structure for the individual system and their relation to the water splitting mechanism.
|
|
| 3. |
- Anversa, Jonas, et al.
(author)
-
High pressure driven superconducting critical temperature tuning in Sb2Se3 topological insulator
- 2016
-
In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 108:21
-
Journal article (peer-reviewed)abstract
- In this letter, we are reporting the change of superconducting critical temperature in Sb2Se3 topological insulator under the influence of an external hydrostatic pressure based on first principles electronic structure calculations coupled with Migdal-Eliashberg model. Experimentally, it was shown previously that Sb2Se3 was undergoing through a transition to a superconducting phase when subjected to a compressive pressure. Our results show that the critical temperature increases up to 6.15K under the pressure unto 40GPa and, subsequently, drops down until 70 GPa. Throughout this pressure range, the system is preserving the initial Pnma symmetry without any structural transformation. Our results suggest that the possible relevant mechanism behind the superconductivity in Sb2Se3 is primarily the electron-phonon coupling.
|
|
| 4. |
|
|
| 5. |
- Araujo, Rafael B., et al.
(author)
-
Na2M2(SO4)(3) (M = Fe, Mn, Co and Ni) : towards high-voltage sodium battery applications
- 2016
-
In: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 18:14, s. 9658-9665
-
Journal article (peer-reviewed)abstract
- Sodium-ion-based batteries have evolved as excellent alternatives to their lithium-ion-based counterparts due to the abundance, uniform geographical distribution and low price of Na resources. In the pursuit of sodium chemistry, recently the alluaudite framework Na2M2(SO4)(3) has been unveiled as a high-voltage sodium insertion system. In this context, the framework of density functional theory has been applied to systematically investigate the crystal structure evolution, density of states and charge transfer with sodium ions insertion, and the corresponding average redox potential, for Na2M2(SO4)(3) (M = Fe, Mn, Co and Ni). It is shown that full removal of sodium atoms from the Fe-based device is not a favorable process due to the 8% volume shrinkage. The imaginary frequencies obtained in the phonon dispersion also reflect this instability and the possible phase transition. This high volume change has not been observed in the cases of the Co- and Ni-based compounds. This is because the redox reaction assumes a different mechanism for each of the compounds investigated. For the polyanion with Fe, the removal of sodium ions induces a charge reorganization at the Fe centers. For the Mn case, the redox process induces a charge reorganization of the Mn centers with a small participation of the oxygen atoms. The Co and Ni compounds present a distinct trend with the redox reaction occurring with a strong participation of the oxygen sublattice, resulting in a very small volume change upon desodiation. Moreover, the average deintercalation potential for each of the compounds has been computed. The implications of our findings have been discussed both from the scientific perspective and in terms of technological aspects.
|
|
| 6. |
- Araujo, Rafael B., et al.
(author)
-
Predicting electrochemical properties and ionic diffusion in Na2+2xMn2-x(SO4)(3) : crafting a promising high voltage cathode material
- 2016
-
In: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 4:2, s. 451-457
-
Journal article (peer-reviewed)abstract
- Sodium ion batteries have emerged as a good alternative to lithium based systems due to their low cost of production. In this scenario, the search for higher voltage, sodium cathodes results in a new promising alluaudite structure Na2+2xMn2-x(SO4)(3). The structural, electronic and Na diffusion properties along with defects have been reported in this investigation within the framework of density functional theory. A band gap of 3.61 eV has been computed and the average deintercalation potential is determined to be 4.11 V vs. Na/Na+. A low concentration of anti-site defects is predicted due to their high formation energy. The biggest issue for the ionic diffusion in the Na2+2xMn2-x(SO4)(3) crystal structure is revealed to be the effect of Mn vacancies increasing the activation energy of Na+ ions that hop along the [001] equilibrium positions. This effect leads to activation energies of almost the same high values for the ionic hop through the [010] direction characterizing a 2D like ionic diffusion mechanism in this system.
|
|
| 7. |
- Araujo, Rafael B., et al.
(author)
-
Unveiling the charge migration mechanism in Na2O2 : implications for sodium-air batteries
- 2015
-
In: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 17:12, s. 8203-8209
-
Journal article (peer-reviewed)abstract
- Metal-air batteries have become promising candidates for modern energy storage due to their high theoretical energy density in comparison to other storage devices. The lower overpotential of Na compared with Li makes Na-air batteries more efficient in terms of battery lifetime. Additionally, the abundance of Na over Li is another advantage for Na batteries compared to Li batteries. Na2O2 is one of the main products of sodium-air battery reactions. The efficiency of air cells is always related to the charge transport mechanisms in the formed product. To unveil these diffusion mechanisms in one of the main products of the cell reaction Na-O-2 we systematically investigate the mobility of charge carriers as well as the electronic structural properties of sodium peroxide. The framework of the density functional theory based on hybrid functional approach is used to study the mobility of charge carriers and intrinsic defects in Na2O2. Our calculations reveal that the formation of small electron and hole polarons is preferentially occurring over the delocalized state in the crystal structure of Na2O2. The migration of these small polarons displays activation energies of about 0.92 eV and 0.32 eV for the electron and hole polarons respectively, while the analysis of the charged sodium vacancy mobility reveals an activation energy of about 0.5 eV. These results suggest that the charge transport in sodium peroxide would mainly occur through the diffusion of hole polarons.
|
|
| 8. |
- Banerjee, Amitava, et al.
(author)
-
Bromination-induced stability enhancement with a multivalley optical response signature in guanidinium [C(NH2)(3)](+)-based hybrid perovskite solar cells
- 2017
-
In: Journal of Materials Chemistry A. - : ROYAL SOC CHEMISTRY. - 2050-7488 .- 2050-7496. ; 5:35, s. 18561-18568
-
Journal article (peer-reviewed)abstract
- Guanidinium lead iodide (GAPbI(3)) has been synthesized experimentally, but stability remains an issue, which can be modulated by the insertion of bromine (Br) into the system. We have performed a systematic theoretical investigation to see how bromination can tune the stability of GAPbI(3). The optical properties were also determined, and we have found formation enthalpy-based stability in the perovskite systems, which are active in the visible and IR region even after bromine insertion and additionally more active in the IR range with the transition from GAPbI(3) to GAPbBr(3). The spin orbit coupling effect is considered throughout the band structure calculations. The ensemble of the primary and secondary gaps in the half and fully brominated hybrid perovskites leads to the phenomenon of a multipeak response in the optical spectra, which can be subsequently attributed as multivalley optical response behaviour. This multivalley optical behaviour enables the brominated guanidinium-based hybrid perovskites to exhibit broad light harvesting abilities, and this can be perceived as an idea for natural multi-junction solar cells.
|
|
| 9. |
- Banerjee, Amitava
(author)
-
Materials Modelling for Energy Harvesting : From Conversion to Application through Storage
- 2019
-
Doctoral thesis (other academic/artistic)abstract
- In this Ph.D. thesis, ab initio density functional theory along with molecular dynamics and global optimization methods are used to unveil and understand the structures and properties of energy relevant materials. In this connection, the following applications are considered: i. electrocatalyst for solar fuel production through water splitting, ii. hybrid perovskite solar cell for generation of electrical energy and iii. Battery materials to store the electrical energy. The water splitting mechanism in terms of hydrogen evolution and oxygen evolution reactions (HER and OER) on the catalytic surfaces has been envisaged based on the free energy diagram, named reaction coordinate, of the reaction intermediates. The Ti-functionalized two-dimensional (2D) borophene monolayer has been emerged as a promising material for HER and OER mechanisms as compared to the pristine borophene sheet. Further investigation in the series of this noble metal free monolayer catalyst is 2D Al2C monolayer both in form of pristine and functionalized with nitrogen (N), phosphorous (P), boron (B), and sulphur (S). It has been observed that only B substituted Al2C shows very close to thermoneutral, that could be the most promising candidate for HER on functionalized Al2C monolayer. The adsorption of O* intermediate is stronger in S-substituted Al2C, whereas it is less strongly adsorbed on N-substituted Al2C. The subsequent consideration is being the case of n-type doping (W) along with Ti codoped in BiVO4 to enhance the efficiency of BiVO4 photoanode for water splitting. The determined adsorption energy and corresponding Gibbs free energies depict that the Ti site is energetically more favorable for water splitting. Moreover, the Ti site possesses a lower overpotential in the W–Ti codoped sample as compared to the mono-W doped sample. We have also explored the effect of mixed cation and mixed anion substitution in the hybrid perovskite in terms of structural stability, electronic properties and optical response of hybrid perovskite crystal structures. It has been found that the insertion of bromine (Br) into the system could modulate the stability of the Guanidinium lead iodide (GAPbI3) hybrid perovskite. Moreover, the band gap of the mixed hybrid perovskite is increased with the inclusion of smaller Br anion while replacing partially the larger iodine (I) anion. Finally the electrochemical storage mechanism for Sodium (Na) and lithium (Li) ion insertion has been envisaged in inorganic electrode (eldfellite, NaFe(SO4)2) as well as in more sustainable organic electrode (di-lithium terephthalate, Li2TP). The full desodiation capability of the eldfellite enhances the capacity while the activation energies (higher than 1 eV) for the Na+ ion diffusion for the charged state lower the ionic insertion rate. The key factor as the variation of Li-O coordination in the terephthalate, for the disproportionation redox reaction in Li2TP is also identified.
|
|
| 10. |
|
|
| 11. |
- Banerjee, Amitava, et al.
(author)
-
Rashba Triggered Electronic and Optical Properties Tuning in Mixed Cation-Mixed Halide Hybrid Perovskites
- 2019
-
In: ACS Applied Energy Materials. - : AMER CHEMICAL SOC. - 2574-0962. ; 2:10, s. 6990-6997
-
Journal article (peer-reviewed)abstract
- The inherent spin-orbit coupling (SOC) effect in non-centrosymmetric crystal structure has laid the foundation of Rashba splitting phenomena. This Rashba splitting directly governs the charge carrier recombination, which eventually controls the carrier lifetime and diffusion length and therefore the solar cell efficiency for such hybrid perovskite materials. In this work, we have performed a rigorous structural search prediction of the mixed cation-mixed halide hybrid perovskites FA(0.83)MA(0.17)Pb(I0.83Br0.17)(3) and FA(0.875)MA(0.125 )Pb(I0.875Br (0.125))(3), which are the two nearest neighbor structures of record efficiency (22.1%) holder FA(0.85)MA(0.15)Pb(I0.85Br0.15)(3) in the structural composition phase space. We have found the prediction routes for a structural search such as the mixed perovskite structure govern the Rashba splitting energy value, depending on whether it has been predicted from FPI (FAPbI(3)) or MPB (MAPbBr(3)) as parent structure, which are leading to the mixed phase FA(0.83)MA(0.17)Pb(I0.83Br0.17)(3) and FA(0.875)MA(0.125)Pb(I0.875Br0.125)(3) respectively. The strong dependency of the splitting energy on the structural phase evolution along with the stoichiometry and space group is also observed, where in the mixed phase, 0.045 difference in concentration could lead to a remarkable difference in the splitting energy, which is more pronounced in the valence band as compared to the conduction band. We have also determined the Goldschmidt tolerance factor to envisage structural stability of the newly predicted crystal structures based on the corresponding chemical route in the composition phase space.
|
|
| 12. |
- Banerjee, Amitava, et al.
(author)
-
Reaction Coordinate Mapping of Hydrogen Evolution Mechanism on Mg3N2Monolayer
- 2020
-
In: International Journal of Hydrogen Energy. - : Elsevier BV. - 0360-3199 .- 1879-3487.
-
Journal article (other academic/artistic)abstract
- In this work, we have envisaged the hydrogen evolution reaction (HER) mechanism on Mg3N2 monolayer based on electronic structure calculations within the framework of density functional theory (DFT) formalism. The semiconducting nature of Mg3N2 monolayer motivates us to investigate the HER mechanism on this sheet. We have constructed the reaction coordinate associated with HER mechanism after determining the hydrogen adsorption energy on Mg3N2 monolayer, while investigating all possible adsorption sites. After obtaining the adsorption energy, we subsequently obtain the adsorption free energy while adding zero point energy difference (Delta ZPE) and entropic contribution (T Delta S). We have not only confined our investigations to a single hydrogen, but have thoroughly observed the adsorption phenomena for increasing number of hydrogen atoms on the surface. We have determined the projected density of states (DOS) in order to find the elemental contribution in the valence band and conduction band regime for all the considered cases. We have also compared the work function value among all the cases, which quantifies the amount of energy required for taking an electron out of the surface. The charge transfer mechanism is also being investigated in order to correlate with the HER mechanism with amount of charge transfer. This is the first attempt on this material to the best of our knowledge, where theoretical investigation has been done to mapping the reaction coordinate of HER mechanism with the associated charge transfer process and the work function values, not only for single hydrogen adsorption, but also for increasing number of adsorbed hydrogen.
|
|
| 13. |
- Banerjee, Amitava, et al.
(author)
-
Scrupulous Probing of Bifunctional Catalytic Activity of Borophene Monolayer : Mapping Reaction Coordinate with Charge Transfer
- 2018
-
In: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 1:8, s. 3571-3576
-
Journal article (peer-reviewed)abstract
- We have envisaged the hydrogen evolution and oxygen evolution reactions (HER and OER) on two-dimensional (2D) noble metal free borophene monolayer based on first-principles electronic structure calculations. We have investigated the effect of Ti functionalization on borophene monolayer from the perspective of HER and OER activities enhancement. We have probed the activities based on the reaction coordinate, which is conceptually related to the adsorption free energies of the intermediates of HER and OER, as well as from the vibrational frequency analysis with the corresponding charge transfer mechanism between the surface and the adsorbate. Tifunctionalized borophene has emerged as a promising material for HER and OER mechanisms. We believe that our probing method, based on reaction coordinate coupled with vibrational analysis that has been validated by the charge transfer mechanism, would certainly become as a robust prediction route for HER and OER mechanisms in coming days.
|
|
| 14. |
- Banerjee, Hrishit, et al.
(author)
-
Cationic Effect on Pressure Driven Spin-State Transition and Cooperativity in Hybrid Perovskites
- 2016
-
In: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 28:22, s. 8379-8384
-
Journal article (peer-reviewed)abstract
- Hybrid or metal organic framework (MOP) perovskites of general composition, ABX(3), are known to show interesting properties that can lead to a variety of technological applications. Our first-principles study shows they are also potential candidates for exhibiting cooperative spin-state transitions upon application of external stimuli. We demonstrate this by considering two specific Fe-based MOF perovskites, namely dimethylammonium iron formate, [CH3NH2CH3][Fe(HCOO)(3)], and hydroxylammonium iron formate, [NH3OH][Fe(HCOO)(3)]. Both the compounds are found to undergo high-spin (S = 2) to low-spin (S = 0) transition at Fe(II) site upon application of moderate strength of hydrostatic pressure, along with large hysteresis. This spin-state transition is signaled by the changes in electronic, magnetic, and optical properties. We find both the transition pressure and the width of the hysteresis to be strongly dependent on the choice of A-site cation, dimethylammonium or hydroxylammonium, implying that tuning of spin-switching properties is achievable by chemical variation of the amine cation in the structure. Our findings open up novel functionalities in this family of materials of recent interest, which can have important usage in sensors and memory devices.
|
|
| 15. |
- Banerjee, Hrishit, et al.
(author)
-
Design and Control of Cooperativity in Spin-Crossover in Metal-Organic Complexes : A Theoretical Overview
- 2017
-
In: INORGANICS. - : MDPI AG. - 2304-6740. ; 5:3
-
Research review (peer-reviewed)abstract
- Metal organic complexes consisting of transition metal centers linked by organic ligands, may show bistability which enables the system to be observed in two different electronic states depending on external condition. One of the spectacular examples of molecular bistability is the spin-crossover phenomena. Spin-Crossover (SCO) describes the phenomena in which the transition metal ion in the complex under the influence of external stimuli may show a crossover between a low-spin and high-spin state. For applications in memory devices, it is desirable to make the SCO phenomena cooperative, which may happen with associated hysteresis effect. In this respect, compounds with extended solid state structures containing metal ions connected by organic spacer linkers like linear polymers, coordination network solids are preferred candidates over isolated molecules or molecular assemblies. The microscopic understanding, design and control of mechanism driving cooperativity, however, are challenging. In this review we discuss the recent theoretical progress in this direction.
|
|
| 16. |
- Bashir, Amna, et al.
(author)
-
Cu-doped nickel oxide interface layer with nanoscale thickness for efficient and highly stable printable carbon-based perovskite solar cell
- 2019
-
In: Solar Energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0038-092X .- 1471-1257. ; 182, s. 225-236
-
Journal article (peer-reviewed)abstract
- The power conversion efficiency (PCE) of hole conductor free carbon-based perovskite solar cells (PSCs) is restricted by the poor charge extraction and recombination losses at the carbon-perovskite interface. For the first time we successfully demonstrated incorporation of thin layer of copper doped nickel oxide (Cu:NiOx) nanoparticles in carbon-based PSCs, which helps in improving the performance of these solar devices. Cu:NiOx nanoparticles have been synthesized by a facile chemical method, and processed into a paste for screen printing. Extensive X-ray Absorption Spectroscopy (XAS) analysis elucidates the co-ordination of Cu in a NiOx matrix and indicates the presence of around 5.4% Cu in the sample. We fabricated a monolithic perovskite module on a 100 cm(2) glass substrate (active area of 70 cm(2)) with a thin Cu:NiOx layer (80 nm), where the champion device shows an appreciated power conversion efficiency of 12.1% under an AM 1.5G illumination. To the best of our knowledge, this is the highest reported efficiency for such a large area perovskite solar device. I-V scans show that the introduction of Cu:NiOx mesoporous scaffold increases the photocurrent, and yields fill factor (FF) values exceeding 57% due to the better interface and increased hole extraction efficiency. Electrochemical Impedance Spectroscopy (EIS) results reinforce the above results by showing the reduction in recombination resistance (R-rec) of the PSCs that incorporates Cu:NiOx interlayer. The perovskite solar modules with a Cu:NiOx layer are stable for more than 4500 h in an ambient environment (25 degrees C and 65% RH), with PCE degradation of less than 5% of the initial value.
|
|
| 17. |
- Bera, Suman, et al.
(author)
-
Limiting Heterovalent B-Site Doping in CsPbI3 Nanocrystals : Phase and Optical Stability
- 2019
-
In: ACS Energy Letters. - : AMER CHEMICAL SOC. - 2380-8195. ; 4:6, s. 1364-1369
-
Journal article (peer-reviewed)abstract
- B-site doping with various metal ions in alpha-CsPbI3 has been proven to be a potential approach in bringing phase stability to these nanocrystals. However, while the doping of various homovalent ions in replacing Pb(II) has been extensively studied, heterovalent doping was observed to be limited. To understand the impact of heterovalent doping, Sb(III) was chosen here as an effective dopant for occupying the Pb(II) position in CsPbI3 nanocrystals. Importantly, it was observed that insertion of Sb(III) also stabilized the crystal phase of these red-emitting nanocrystals, but only with limited doping. However, with more intake, the cube shape turned to platelet and therefore also reduced the stability. Details of the insights of formation of these doped nanostructures are investigated, and further, these were implemented for photovoltaic application and comparable efficiency was recorded.
|
|
| 18. |
- Bhattacharya, Prosun, 1962-, et al.
(author)
-
Prevalence of SARS-CoV-2 in Communities Through Wastewater Surveillance—a Potential Approach for Estimation of Disease Burden
- 2021
-
In: Current Pollution Reports. - : Springer Nature. - 2198-6592. ; 7:2, s. 160-166
-
Journal article (peer-reviewed)abstract
- The episodic outbreak of COVID-19 due to SARS-CoV-2 is severely affecting the economy, and the global count of infected patients is increasing. The actual number of patients had been underestimated due to limited facilities for testing as well as asymptomatic nature of the expression of COVID-19 on individual basis. Tragically, for emerging economies with high population density, the situation has been more complex due to insufficient testing facilities for diagnosis of the disease. However, the recent reports about persistent shedding of viral RNA of SARS-CoV-2 in the human feces have created a possibility to track the prevalence and trends of the disease in communities, known as wastewater-based epidemiology (WBE). In this article, we highlight the current limitations and future prospects for WBE to manage pandemics.
|
|
| 19. |
- Callini, Elsa, et al.
(author)
-
Nanostructured materials for solid-state hydrogen storage : A review of the achievement of COST Action MP1103
- 2016
-
In: International journal of hydrogen energy. - : Elsevier. - 0360-3199 .- 1879-3487. ; 41:32, s. 14404-14428
-
Journal article (peer-reviewed)abstract
- In the framework of the European Cooperation in Science and Technology (COST) Action MP1103 Nanostructured Materials for Solid-State Hydrogen Storage were synthesized, characterized and modeled. This Action dealt with the state of the art of energy storage and set up a competitive and coordinated network capable to define new and unexplored ways for Solid State Hydrogen Storage by innovative and interdisciplinary research within the European Research Area. An important number of new compounds have been synthesized: metal hydrides, complex hydrides, metal halide ammines and amidoboranes. Tuning the structure from bulk to thin film, nanoparticles and nanoconfined composites improved the hydrogen sorption properties and opened the perspective to new technological applications. Direct imaging of the hydrogenation reactions and in situ measurements under operando conditions have been carried out in these studies. Computational screening methods allowed the prediction of suitable compounds for hydrogen storage and the modeling of the hydrogen sorption reactions on mono-, bi-, and three-dimensional systems. This manuscript presents a review of the main achievements of this Action.
|
|
| 20. |
|
|
| 21. |
- Chakraborty, Sudip, et al.
(author)
-
Current computational trends in polyanionic cathode materials for Li and Na batteries
- 2018
-
In: Journal of Physics. - : Institute of Physics (IOP). - 0953-8984 .- 1361-648X. ; 30:28
-
Research review (peer-reviewed)abstract
- A long-standing effort has been devoted for the development of high energy density cathodes both for Li-and Na-ion batteries (LIBs and SIBs). The scientific communities in battery research primarily divide the Li- and Na-ion cathode materials into two categories: layered oxides and polyanionic compounds. Researchers are trying to improve the energy density of such materials through materials screening by mixing the transition metals or changing the concentration of Li or Na in the polyanionic compounds. Due to the fact that there is more stability in the polyanionic frameworks, batteries based on these materials mostly provide a prolonged cycling life as compared to the layered oxide materials. Nevertheless, the bottleneck for such compounds is the weight penalty from polyanionic groups that results into the lower capacity. The anion engineering could be considered as an essential way out to design such polyanionic compounds to resolve this issue and to fetch improved cathode performance. In this topical review we present a systematic overview of the polyanionic cathode materials used for LIBs and SIBs. We will also present the computational methodologies that have become significantly relevant for battery research. We will make an attempt to provide the theoretical insight with a current development in sulfate (SO4), silicate (SiO4) and phosphate (PO4) based cathode materials for LIBs and SIBs. We will end this topical review with the future outlook, that will consist of the next generation organic electrode materials, mainly based on conjugated carbonyl compounds.
|
|
| 22. |
|
|
| 23. |
|
|
| 24. |
- Chakraborty, Sudip, et al.
(author)
-
Quantum Confinement Effect in Pristine and Oxygen Covered Silicon Nanocrystals with Surface States
- 2011
-
In: Journal of Computational and Theoretical Nanoscience. - : American Scientific Publishers. - 1546-1955 .- 1546-1963. ; 8:9, s. 1739-1743
-
Journal article (peer-reviewed)abstract
- Absorption spectra for pristine silicon and oxygen capped silicon nanocrystals (ncs) are computed using time dependent local density approximation (TDLDA) in the size regime of 1.0 to 1.5 nm. These clusters show very small highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gaps. This indicates presence of surface states. The partial density of states (PDOS) for these clusters confirms the presence of surface states when compared to the corresponding ncs with hydrogen passivation. The HOMO–LUMO gaps do not show any size dependence. However the optical absorption gaps show the quantum confinement effect (QCE) for both the types of clusters. The oxygen capped silicon ncs are prepared following the wet chemical route. The optical absorption spectrum of experimentally prepared ncs is compared with the computed one. Experimental results support the theoretical argument explaining the QCE in these clusters.
|
|
| 25. |
- Chakraborty, Sudip, et al.
(author)
-
Rational Design : A High-Throughput Computational Screening and Experimental Validation Methodology for Lead-Free and Emergent Hybrid Perovskites
- 2017
-
In: ACS Energy Letters. - : American Chemical Society (ACS). - 2380-8195. ; 2:4, s. 837-845
-
Journal article (peer-reviewed)abstract
- Perovskite solar cells, with efficiencies of 22.1%, are the only solution-processable technology to outperform multicrystalline silicon and thin-film solar cells. Whereas substantial progress has been made in scalability and stability, toxicity concerns drive the need for lead replacement, intensifying research into the broad palette of elemental substitutions, solid solutions, and multidimensional structures. Perovskites have gone from comprising three to more than eight (CH3NH3, HC(NH2)(2), Cs, Rb, Pb, Sn, I, Br) organic and inorganic constituents, and a variety of new embodiments including layered, double perovskites, and metal-deficient perovskites are being explored. Although most experimentation is guided by intuition and trial-and-error-based Edisonian approaches, rational strategies underpinned by computational screening and targeted experimental validation are emerging. In addressing emergent perovskites, this perspective discusses the rational design methodology leveraging density functional theory-based high-throughput computational screening coupled to downselection strategies to accelerate the discovery of materials and industrialization of perovskite solar cells.
|
|
| 26. |
- Chakraborty, Sudip, et al.
(author)
-
Relative Localization Prediction in Covalent Clusters : An Ab Initio Theory Driven Quest
- 2012
-
In: Advanced Science Letters. - : American Scientific Publishers. - 1936-6612 .- 1936-7317. ; 18:1, s. 208-212
-
Journal article (peer-reviewed)abstract
- A method to estimate the relative binding energies of atom within a covalently bonded cluster is proposed. The method uses projected density of states (PDOS) for the individual atoms in the cluster. A parameter similar to variance is defined over certain region of PDOS. The value is seen to be inversely related to the local binding energy of the atom. The method is applied to Si19O8 and Si19O10 clusters to determine the relatively weakly bound atoms in these clusters. Fragmentation of the clusters using simulated annealing reveals that those atoms are fragmented which are identified to be weakly bound from the proposed method.
|
|
| 27. |
- Chakraborty, Sudip, et al.
(author)
-
Structural and Optical Properties of Oxygenated Silicon Quantum Dots
- 2011
-
In: Advanced Science Letters. - : American Scientific Publishers. - 1936-6612. ; 4:11-12, s. 3580-3584
-
Journal article (peer-reviewed)abstract
- Silicon quantum dots of size as small as 1 nm in diameter were prepared by wet chemical route. These clusters are found to be covered with oxygen and hydrocarbon molecules. The optical measurements reveal strong absorption around 4.67 eV and weak absorption at lower energies. The clusters show a broad luminescence around 3.87 eV. These quantum dots are modeled using ab-initio Car Parinello Molecular Dynamics and computational studies explain the absorption spectrum of the clusters over observed energy range. In principle, these quantum dots can be useful as scintillating layer on crystalline silicon solar cells to enhance the photovoltaic efficiency.
|
|
| 28. |
|
|
| 29. |
- Das, Suman, et al.
(author)
-
Probing the pseudo-1-D ion diffusion in lithium titanium niobate anode for Li-ion battery
- 2016
-
In: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 18:32, s. 22323-22330
-
Journal article (peer-reviewed)abstract
- Comprehensive understanding of the charge transport mechanism in the intrinsic structure of an electrode material is essential in accounting for its electrochemical performance. We present here systematic experimental and theoretical investigations of Li+-ion diffusion in a novel layered material, viz. lithium titanium niobate. Lithium titanium niobate (exact composition Li0.55K0.45TiNbO5 center dot 1.06H(2)O) is obtained from sol-gel synthesized potassium titanium niobate (KTiNbO5) by an ion-exchange method. The Li+-ions are inserted and de-inserted preferentially into the galleries between the octahedral layers formed by edge and corner sharing TiO6 and NbO6 octahedral units and the effective chemical diffusion coefficient, is estimated to be 3.8 x 10(-11) cm(2) s(-1) using the galvanostatic intermittent titration technique (GITT). Calculations based on density functional theory (DFT) strongly confirm the anisotropic Li+-ion diffusion in the interlayer galleries and that Li+-ions predominantly diffuse along the crystallographic b-direction. The preferential Li+-ion diffusion along the b-direction is assisted by line-defects, which are observed to be higher in concentration along the b-direction compared to the a-and c-directions, as revealed by high resolution electron microscopy. The Li-Ti niobate can be cycled to low voltages (approximate to 0.2 V) and show stable and satisfactory battery performance over 100 cycles. Due to the possibility of cycling to low voltages, cyclic voltammetry and X-ray photoelectron spectroscopy convincingly reveal the reversibility of Ti3+ <-> Ti2+ along with Ti4+ <-> Ti3+ and Nb5+ <-> Nb4+.
|
|
| 30. |
- Das, T., et al.
(author)
-
Charge transfer driven interaction of CH4, CO2 and NH3 with TiS2 monolayer : Influence of vacancy defect
- 2021
-
In: Catalysis Today. - : Elsevier B.V.. - 0920-5861 .- 1873-4308. ; 370, s. 189-195
-
Journal article (peer-reviewed)abstract
- In this work we have investigated the dissociation of hydrogen rich CH4 and NH3 molecules along with CO2 on the surface of pristine and various defect induced TiS2 monolayer. The aim is to see whether the monolayer surfaces are able to produce H2 by decomposing the feedstock adsorbates and also to examine whether it can be a sorbent for CO2. We have tried to explore a monolayer surface which can simultaneously act as a catalyst to dissociate CH4, as well as to adsorb CO2 which is the only harmful by-product in steam reforming method for hydrogen production from CH4. The hydrogen generation has been predicted from the nature of gas adsorption, and the adsorption energies have been estimated to see whether it falls under chemisorption or physisorption range. Both S and Ti vacancy defects have been studied and the first-principles electronic structure calculation helps to envisage the charge redistribution of the three adsorbates on both pristine and defective TiS2 surfaces.
|
|
| 31. |
- Das, Tisita, et al.
(author)
-
Functionalization and Defect-Driven Water Splitting Mechanism on a Quasi-Two-Dimensional TiO2 Hexagonal Nanosheet
- 2019
-
In: ACS Applied Energy Materials. - : American Chemical Society (ACS). - 2574-0962. ; 2:7, s. 5074-5082
-
Journal article (peer-reviewed)abstract
- In this work, we have dealt with the functionalization of a newly reported quasi-2D hexagonal nanosheet (HNS) of titanium dioxide (TiO2) for photocatalytic water splitting to generate hydrogen and oxygen. Functionalization has been carried out by creating a single oxygen vacancy defect as well as by incorporating substitutional doping with C, N, P, and S atoms at the O site of TiO2 HNS. The effects of functionalization and vacancy defects on the structural and electronic properties of HNS have been investigated by determining the corresponding projected density of states. It has been observed that functionalization causes a shift in the VBM and CBM of HNS, which in principle influences the catalytic activity. In addition, we have determined the work function for these materials in order to correlate them with the electrochemical activities of different considered HNSs. The catalytic activity has been predicted by determining the reaction coordinate as constructed from the free energies of the different reaction intermediates involved in HER and OER Among all of the systems that we have studied, HNS with an oxygen monovacancy has emerged as the best possible candidate for the water-splitting mechanism.
|
|
| 32. |
- Das, Tisita, et al.
(author)
-
TiS2 Monolayer as an Emerging Ultrathin Bifunctional Catalyst : Influence of Defects and Functionalization
- 2019
-
In: ChemPhysChem. - : Wiley-VCH Verlag. - 1439-4235 .- 1439-7641. ; 20:4, s. 608-617
-
Journal article (peer-reviewed)abstract
- We have envisaged the hydrogen evolution and oxygen evolution reactions (HER and OER) on a two-dimensional (2D) noble-metal-free titanium disulfide (TiS2) monolayer, which belongs to the exciting family of transition metal dichalcogenides (TMDCs). Our theoretical investigation to probe the HER and OER on both the H and T phases of 2D TiS2 is based on electronic-structure calculations witihin the framework of density functional theory (DFT). Since TiS2 is the lightest compound among the group-IV TMDCs, it is worth exploring the catalytic activity of a TiS2 monolayer through the functionalization at the anion (S) site, substituting with P, N, and C dopants as well as by incorporating single sulfur vacancy defects. We have investigated the effect of functionalization and vacancy defects on the structural, electronic, and optical response of a TiS2 monolayer by determining the density of states, work-function, and optical absorption spectra. We have determined the HER and OER activities for the functionalized and defective TiS2 monolayers based on the reaction coordinate, which can be constructed from the adsorption free energies of the intermediates (H*, O*, OH* and OOH*, where * denotes the adosrbed state) in the HER and OER mechanisms. Finally, we have shown that TiS2 monolayers are emerging as a promising material for the HER and OER mechanisms under the influence of functionalization and defects.
|
|
| 33. |
- Djouambi, Nadia, et al.
(author)
-
New Concept on Photocatalytic Degradation of Thiophene Derivatives : Experimental and DFT Studies
- 2018
-
In: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 122:27, s. 15646-15651
-
Journal article (peer-reviewed)abstract
- In this study, the photocatalytic degradation of seven sulfur compounds (2-methylthiophene, 3-methylthiophene, 2-phenylthiophene, 3-phenylthiophene, 2,5-diphenylthiophene, 2-(2-thienyl) pyridine, and 2-(3-thienyl) pyridine in semiaqueous medium are compared to thiophene. The apparent-reaction-rate constant (k) is found to decrease in the following order: 2,5-diphenylthiophene > 2-(2-thienyl) pyridine > 2-penhylthiophene methylthiophene > 3-penhylthiophene > 2-methylthiophene > 2-(3-thienyl) pyridine > 3-thiophene. From the data obtained by UV light absorption (lambda(max)) measurements and electronic structure calculations (frontier orbitals energy, global hardness, and global softness), the kinetic parameters of the reaction have been determined. Among the studied compounds, thiophene with a high lambda(max) and low calculated LUMO-HOMO gap energy has showed higher activity under UV irradiation. Interestingly, a lower activity is observed with low lambda(max) and high LUMO-HOMO gap energy. This demonstrates, for the first time, that the reactivity depends essentially on the thermodynamic stability of the sulfur compound rather than on the nature or the position of the substituent on the ring.
|
|
| 34. |
- Dwibedi, Debasmita, et al.
(author)
-
Ionothermal Synthesis of High-Voltage Alluaudite Na2+2xFe2-x(SO4)(3) Sodium Insertion Compound : Structural, Electronic, and Magnetic Insights
- 2016
-
In: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 8:11, s. 6982-6991
-
Journal article (peer-reviewed)abstract
- Exploring future cathode materials for sodium-ion batteries, alluaudite class of Na2Fe2II(SO4)(3) has been recently unveiled as a 3.8 V positive insertion candidate (Barpanda et al. Nat. Commun. 2014, 5, 4358). It forms an Fe-based polyanionic compound delivering the highest Fe-redox potential along with excellent rate kinetics and reversibility. However, like all known SO4-based insertion materials, its synthesis is cumbersome that warrants careful processing avoiding any aqueous exposure. Here, an alternate low temperature ionothermal synthesis has been described to produce the alluaudite Na2+2xFe2-xII(SO4)(3). It marks the first demonstration of solvothermal synthesis of alluaudite Na2+2xM2-xII(SO4)(3) (M = 3d metals) family of cathodes. Unlike classical solid-state route, this solvothermal route favors sustainable synthesis of homogeneous nanostructured alluaudite products at only 300 degrees C, the lowest temperature value until date. The current work reports the synthetic aspects of pristine and modified ionothermal synthesis of Na2+2xFe2-xII(SO4)(3) having tunable size (300 nm similar to 5 mu m) and morphology. It shows antiferromagnetic ordering below 12 K. A reversible capacity in excess of 80 mAh/g was obtained with good rate kinetics and cycling stability over 50 cycles. Using a synergistic approach combining experimental and ab initio DFT analysis, the structural, magnetic, electronic, and electrochemical properties and the structural limitation to extract full capacity have been described.
|
|
| 35. |
- Dwibedi, Debasmita, et al.
(author)
-
Na2.32Co1.84(SO4)(3) as a new member of the alluaudite family of high-voltage sodium battery cathodes
- 2017
-
In: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; 46:1, s. 55-63
-
Journal article (peer-reviewed)abstract
- Electrochemical energy storage has recently seen tremendous emphasis being placed on the large-scale (power) grid storage. Sodium-ion batteries are capable of achieving this goal with economic viability. In a recent breakthrough in sodium-ion battery research, the alluaudite framework (Na2Fe2(SO4)(3)) has been reported, with the highest Fe3+/Fe2+ redox potential (ca. 3.8 V, Barpanda, et al., Nat. Commun., 2014, 5, 4358). Exploring this high-voltage sodium insertion system, we report the discovery of Na2+2xCo2-x(SO4)(3) (x = 0.16) as a new member of the alluaudite class of cathode. Stabilized by low-temperature solid-state synthesis (T <= 350 degrees C),this novel Co-based compound assumes a monoclinic structure with C2/c symmetry, which undergoes antiferromagnetic ordering below 10.2 K. Isotypical to the Fe-homologue, it forms a complete family of solid-solution Na2+2x(Fe1-yCoy)(2-x)(SO4)(3) [ y = 0-1]. Ab initio DFT analysis hints at potential high voltage operation at 4.76-5.76 V (vs. Na), depending on the degree of desodiation involving a strong participation of the oxygen sub-lattice. With the development of safe organic electrolytes, Na2+2xCo2-x(SO4)(3) can work as a cathode material (similar to 5 V) for sodium-ion batteries.
|
|
| 36. |
- Dwibedi, Debasmita, et al.
(author)
-
Na2.44Mn1.79(SO4)(3) : a new member of the alluaudite family of insertion compounds for sodium ion batteries
- 2015
-
In: Journal of Materials Chemistry A. - : Royal Society of Chemistry (RSC). - 2050-7488 .- 2050-7496. ; 3:36, s. 18564-18571
-
Journal article (peer-reviewed)abstract
- Sodium-ion batteries have been extensively pursued as economic alternatives to lithium-ion batteries. Investigating the polyanion chemistry, alluaudite structured Na2Fe2II(SO4)(3) has been recently discovered as a 3.8 V positive electrode material (Barpanda et al., Nature Commun., 5: 4358, 2014). Registering the highest ever Fe-III/Fe-II redox potential (vs. Na/Na+) and formidable energy density, it has opened up a new polyanion family for sodium batteries. Exploring the alluaudite family, here we report isotypical Na2+2xMn2-xII(SO4)(3) (x = 0.22) as a novel high-voltage cathode material for the first time. Following low-temperature (ca. 350 degrees C) solid-state synthesis, the structure of this new alluaudite compound has been solved adopting a monoclinic framework (s.g. C2/c) showing antiferromagnetic ordering at 3.4 K. Synergising experimental and ab initio DFT investigation, Na2+2xMn2-xII(SO4)(3) has been found to be a potential high-voltage (ca. 4.4 V) cathode material for sodium batteries.
|
|
| 37. |
|
|
| 38. |
- Gaikwad, Prashant V., et al.
(author)
-
Cluster assembly route to a novel octagonal two-dimensional ZnO monolayer
- 2017
-
In: Journal of Physics. - 0953-8984 .- 1361-648X. ; 29:33
-
Journal article (peer-reviewed)abstract
- To explore the possibility of cluster assembly resulting in a two-dimensional (2D) stable monolayer of ZnO, a systematic study is performed on the structural evolution of bare and passivated stoichiometric clusters of ZnnOn, n = 1-8, using density-functional-theory-based first principles electronic structure calculations. The changes in hybridization are investigated with the aid of the site-projected partial density of states and partial charge density, while the effect of passivation and size on the ionicity of the cluster is studied using Bader charge analysis. The structural and chemical properties are found to be influenced by the coordination number of atoms in the clusters irrespective of the coordinating species. The physical parameters and hybridization of the states for the clusters on passivation resemble those of the bulk. Passivation thus provides an environment that leads to the stability of the clusters. Cluster assembly using the stable cluster geometries of passivated clusters (without the passivating atoms) has been shown to lead to stable 2D structures. This stability has been studied on the basis of binding energy, vibrational frequency, phonon dispersion and thermal properties. A new octagonal 2D monolayer planar geometry of ZnO is predicted.
|
|
| 39. |
- Ghosh, Biplab, et al.
(author)
-
Poor Photovoltaic Performance of Cs3Bi2I9 : An Insight through First-Principles Calculations
- 2017
-
In: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 121:32, s. 17062-17067
-
Journal article (peer-reviewed)abstract
- Bismuth-based halide perovskite derivatives have now attracted huge attention for photovoltaic (PV) applications after the unparalleled success of lead-based halide perovskites. However, the performances of PV devices based on these compounds are poor, despite theoretical predictions. In this Article, we have investigated the electronic structure and defect formation energies of Cs3Bi2I9 using density functional theory (DFT) calculations. The calculated electronic bandstructure indicates an indirect bandgap and high carrier effective masses. Our calculations reveal a large stability region for this compound; however, deep level defects are quite prominent. Even the varying chemical potentials from the stoichiometric region do not eliminate the presence of deep defects, ultimately limiting photovoltaic efficiencies.
|
|
| 40. |
- Guha, Anku, et al.
(author)
-
Mechanistic Insight into Enhanced Hydrogen Evolution Reaction Activity of Ultrathin Hexagonal Boron Nitride-Modified Pt Electrodes
- 2018
-
In: ACS Catalysis. - : AMER CHEMICAL SOC. - 2155-5435. ; 8:7, s. 6636-6644
-
Journal article (peer-reviewed)abstract
- Enhancing the intrinsic activity of a benchmarked electrocatalyst such as platinum (Pt) is highly intriguing from fundamental as well as applied perspectives. In this work, hydrogen evolution reaction (HER) activity of Pt electrodes, benchmarked HER catalysts, modified with ultrathin sheets of hexagonal boron nitride (h-BN) is studied in acidic medium (Pt/h-BN), and augmented HER performance, in terms of the overpotential at a 10 mA cm(-2) current density (10 mV lower than that of Pt nanoparticles) and a lower Tafel slope (29 +/- 1 mV/decade), of the Pt/h-BN system is demonstrated. The effects of h-BN surface modification of bulk Pt as well as Pt nanoparticles are studied, and the origin of such an enhanced HER activity is probed using density functional theory-based calculations. The HER charge transfer resistance of h-BN-modified Pt is found to be drastically reduced, and this enhances the charge transfer kinetics of the Pt/h-BN system because of the synergistic interaction between h-BN and Pt. An enormous reduction in the hydrogen adsorption energy on h-BN monolayers is also found when they are placed over the Pt electrode [-2.51 eV (h-BN) to -0.25 eV (h-BN over Pt)]. Corrosion preventive atomic layers such as h-BN-protected Pt electrodes that perform better than Pt electrodes do open possibilities of benchmarked catalysts by simple modification of a surface via atomic layers.
|
|
| 41. |
- Gupta, Divyani, et al.
(author)
-
High yield selective electrochemical conversion of N-2 to NH(3)via morphology controlled silver phosphate under ambient conditions
- 2022
-
In: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 10:38, s. 20616-20625
-
Journal article (peer-reviewed)abstract
- Development of a highly active catalyst for the synthesis of ammonia via the electrochemical dinitrogen reduction reaction (e-NRR) is an immense challenge. We report the modification of metallic Ag with inorganic phosphate to obtain Ag3PO4 as an effective electrocatalyst for the e-NRR in alkaline media under ambient conditions. The designed Ag3PO4 catalyst can effectually suppress the HER. The e-NRR activity was improved by fine-tuning the morphology by a template free one-pot synthesis. The synthesised Ag3PO4 having cuboidal morphology is shown to have superior activity and stability towards the e-NRR witnessed from a high faradaic efficiency of 26.67%, yield rate of 456.75 mu g h(-1) mg(cat)(-1) and TOF value of 0.46 h(-1) at a positive potential of 0 V vs. RHE in 0.1 M KOH. Careful examination of any N-contaminants present in catalyst/electrolyte/gas-feed is carried out by UV-vis spectroscopy and gas-purification methods prior to e-NRR measurements to eliminate any false NH3 production. Also, the true source of NH3 production is confirmed by means of N-15-isotope labelling experiments via(1)H-NMR spectroscopy.
|
|
| 42. |
- Gupta, Divyani, et al.
(author)
-
Local electrocatalytic activity of PtRu supported on nitrogen-doped carbon nanotubes towards methanol oxidation by scanning electrochemical microscopy
- 2021
-
In: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 9:37, s. 21291-21301
-
Journal article (peer-reviewed)abstract
- Nitrogen-doped carbon nanotubes (NCNTs) were synthesized by treating HNO3-oxidized carbon nanotubes (CNTs) in an NH3 flow at different temperatures. PtRu nanoparticles were decorated over NCNTs. The PtRu catalysts were prepared by an impregnation-reduction method from metal chloride precursors with a total metal loading of about 10 wt%. The electrocatalytic activity with respect to methanol oxidation was studied using electrochemical and scanning electrochemical microscopy (SECM) measurements. Transmission electron microscopy revealed the spherical shape and narrow particle size distribution of the PtRu particles over NCNTs with average particle sizes of similar to 3-5 nm. A detailed X-ray photoelectron spectroscopy study was performed to quantitatively identify different nitrogen functional groups and to evaluate their role in the observed enhanced catalytic activity towards methanol oxidation. The determination of the local electrocatalytic activity of the proposed catalyst towards methanol oxidation and simultaneous evaluation of the intermediates produced during methanol oxidation were achieved using SECM. Density functional theory studies were performed to understand the adsorption sites of methanol and intermediates on different reactive sites and to investigate possible reaction mechanisms.
|
|
| 43. |
- Gupta, Divyani, et al.
(author)
-
Self-powered NH3 synthesis by trifunctional Co2B-based high power density Zn-air batteries
- 2023
-
In: Journal of Materials Chemistry A. - : Royal Society of Chemistry. - 2050-7488 .- 2050-7496. ; 11:23, s. 12223-12235
-
Journal article (peer-reviewed)abstract
- The electrochemical production of NH3 by Zn-air batteries is a viable and economical approach to realize sustainable and competent energy conversion. We report the environment friendly, cost-effective, and energy efficient sonochemical synthesis of amorphous Co2B nanosheets for trifunctional electrocatalysis. The catalyst exhibits a high NH3 yield rate (2.98 mg h(-1) mg(cat.)(-1)), F.E (20.45%), and TOF of 0.74 h(-1) at -0.3 V vs. RHE, thereby unveiling an outstanding performance for the artificial ammonia synthesis. The reliable and true NH3 production is premediated by following rigorous protocol that involves the purification of gas supplies, elimination of N-contaminants, and quantification of NH3 by different methods, UV-Vis spectroscopy and N-15(2) isotope labelling experiments. More interestingly, DFT calculations on the Co2B catalyst surface shed light on the efficient NRR owing to the presence of Co active sites and possible HER suppression. The optimized Co2B catalyst shows outstanding oxygen bifunctional activity. When employed as an air-cathode for Zn-air batteries, it exhibited remarkable electrocatalytic activity delivering an open circuit potential of 1.45 V with a high power density of 500 mW cm(-2) and an energy density of 1078 W h kg(-1), which can perform NH3 generation with an overall NH3 production yield rate of 1.048 mg h(-1) mg(cat.)(-1).
|
|
| 44. |
- Hussain, Tanveer, et al.
(author)
-
BC3 Sheet Functionalized with Lithium-Rich Species Emerging as a Reversible Hydrogen Storage Material
- 2015
-
In: ChemPhysChem. - : Wiley. - 1439-4235 .- 1439-7641. ; 16:3, s. 634-639
-
Journal article (peer-reviewed)abstract
- The decoration of a BC3 monolayer with the polylithiated molecules CLi4 and OLi2 has been extensively investigated to study the hydrogen-storage efficiency of the materials by first principles electronic structure calculations. The binding energies of both lithiated species with the BC3 substrate are much higher than their respective cohesive energies, which confirms the stability of the doped systems. A significant positive charge on the Li atom in each of the dopants facilitates the adsorption of multiple H-2 molecules under the influence of electrostatic and van der Waals interactions. We observe a high H-2-storage capacity of 11.88 and 8.70 wt% for the BC3-CLi4 and BC3-OLi2 systems, respectively, making them promising candidates as efficient energy-storage systems.
|
|
| 45. |
- Hussain, Tanveer, et al.
(author)
-
Defect and Substitution-Induced Silicene Sensor to Probe Toxic Gases
- 2016
-
In: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 120:44, s. 25256-25262
-
Journal article (peer-reviewed)abstract
- Structural, electronic, and gas-sensing properties of pure, defected, and substituted silicene monolayer have been studied using first-principles calculations based on density functional theory. The spin-polarized calculations with van der Waals effect taken into consideration have revealed that the pristine silicene sheet rarely adsorbs the CO2, H2S, and SO2 gas molecules, which restricts the gas-sensing application of this 2D material. However, inducing vacancy defect in silicene drastically changes the electronic properties, and as a consequence it also improves the binding of exposed gas molecules significantly. Our Bader charge analysis reveals that a considerable amount of charge is being transferred from the defected silicene to the gases, resulting in binding energy improvement between silicene and the gas molecules. The change in binding energies has further been explained by plotting density of states. In addition to the vacancy defects, we have also considered the substitution of Al, B, N, and S in silicene. We found that the sensing propensity of silicene is more sensitive to the vacancy defect, as compared with the impurities.
|
|
| 46. |
- Hussain, T., et al.
(author)
-
Defected and Functionalized Germanene-based Nanosensors under Sulfur Comprising Gas Exposure
- 2018
-
In: ACS Sensors. - : American Chemical Society (ACS). - 2379-3694. ; 3:4, s. 867-874
-
Journal article (peer-reviewed)abstract
- Efficient sensing of sulfur containing toxic gases like H2S and SO2 is of the utmost importance due to the adverse effects of these noxious gases. Absence of an efficient 2D-based nanosensor capable of anchoring H2S and SO2 with feasible binding and an apparent variation in electronic properties upon the exposure of gas molecules has motivated us to explore the promise of a germanene nanosheet (Ge-NS) for this purpose. In the present study, we have performed a comprehensive computational investigation by means of DFT-based first-principles calculations to envisage the structural, electronic, and gas sensing properties of pristine, defected, and metal substituted Ge-NSs. Our initial screening has revealed that although interaction of SO2 with pristine Ge-NSs is within the desirable range, H2S binding however falls below the required values to guarantee an effective sensing. To improve the binding characteristics, we have considered the interactions between H2S and SO2 with defected and metal substituted Ge-NS. The systematic removals of Ge atoms from a reasonably large super cell lead to monovacancy, divacancies, and trivacancies in Ge-NS. Similarly, different transition metals like As, Co, Cu, Fe, Ga, Ge, Ni, and Zn have been substituted into the monolayer to realize substituted Ge-NS. Our van der Waals corrected DFT calculations have concluded that the vacancy and substitution defects not only improve the binding characteristics but also enhance the sensing propensity of both H2S and SO2. The total and projected density of states show significant variations in electronic properties of pristine and defected Ge-NSs before and after the exposure to the gases, which are essential in constituting a signal to be detected by the external circuit of the sensor. We strongly believe that our present work would not only advance the knowledge towards the application of Ge-NS-based sensing but also provide motivation for the synthesis of such efficient nanosensor for H2S and SO2 based on Ge monolayer.
|
|
| 47. |
- Hussain, Tanveer, et al.
(author)
-
Enhancement of energy storage capacity of Mg functionalized silicene and silicane under external strain
- 2014
-
In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 105:12, s. 123903-
-
Journal article (peer-reviewed)abstract
- The electronic structure, stability, and hydrogen storage capacity of strain induced Mg functionalized silicene (SiMg) and silicane (SiHMg) monolayers have been studied by means of van der Waals induced first principles calculations. A drastic increase in the binding energy of Mg adatoms on both the monolayers under the biaxial symmetric strain of 10% ensures the uniform distribution of dopants over the substrates. A significant positive charge on each Mg accumulates a maximum of six H-2 molecules with H-2 storage capacity of 8.10% and 7.95% in case of SiMg and SiHMg, respectively. The average adsorption energy for H-2 molecules has been found ideal for practical H-2 storage materials.
|
|
| 48. |
- Hussain, Tanveer, et al.
(author)
-
Functionalization of hydrogenated silicene with alkali and alkaline earth metals for efficient hydrogen storage
- 2013
-
In: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 15:43, s. 18900-18905
-
Journal article (peer-reviewed)abstract
- First principles density functional theory has been employed to investigate the electronic structure along with the stability, bonding mechanism, band gap and charge transfer of metal functionalized hydrogenated silicene (SiH), or silicane, in order to envisage the hydrogen storage capacity. Various metal adatoms including Li, Na, K, Be, Mg and Ca have been doped on the most stable chair like configuration of silicane. The corresponding binding energies and charge transfer mechanism have been discussed from the perspective of H-2 storage ability. The Li and Na metal adatoms have been found to be ideally suitable not only for their strong metal to substrate binding and uniform distribution over the substrate but also for their high capacity for storage of hydrogen. The stability of both Li and Na functionalized SiH has also been confirmed by MD simulations. It was found that both Li+ and Na+ adsorbed four H-2 molecules attaining reasonably high storage capacities of 6.30 wt% and 5.40 wt% respectively with average adsorption energies lying within the range suitable for practical H-2 storage applications, in contrast with alkaline earth metals.
|
|
| 49. |
- Hussain, Tanveer, et al.
(author)
-
Improved sensing characteristics of methane over ZnO nano sheets upon implanting defects and foreign atoms substitution
- 2017
-
In: Nanotechnology. - : Institute of Physics Publishing (IOPP). - 0957-4484 .- 1361-6528. ; 28:41
-
Journal article (peer-reviewed)abstract
- Thanks to the growing interests of metal oxide sensors in environmental and industrial uses, this study presents the sensing mechanism of methane gas (CH4) on recently synthesized two-dimensional form of ZnO, ZnO nano sheets (ZnO-NS). The adsorption energy of CH4 on pristine ZnO-NS, calculated by means of van derWaals corrected first-principles calculations, is found to be insufficient restricting its application as an efficient nano sensor. However, the creation of (O/Zn) vacancies and the substitution of foreign dopants into ZnO-NS considerably intensify the binding energy of CH4. Through a comprehensive energetic analysis, it is observed that among all the substituents, boron (B), sulphur (S) and gallium (Ga) improves the binding of CH4 to 2.75, 6.1 and 7.5 times respectively than its values on pristine ZnO-NS. In addition to the CH4 binding energies falling ideally between physisorption and chemisorption range, a prominent variation in the electronic properties before and after CH4 exposure indicates the promise of substituted Zn-NS as a useful nano sensors.
|
|
| 50. |
- Hussain, Tanveer, et al.
(author)
-
Improvement in Hydrogen Desorption from - and -MgH2 upon Transition-Metal Doping
- 2015
-
In: ChemPhysChem. - : Wiley. - 1439-4235 .- 1439-7641. ; 16:12, s. 2557-2561
-
Journal article (peer-reviewed)abstract
- A thorough study of the structural, electronic, and hydrogen-desorption properties of - and -MgH2 phases substituted by selected transition metals (TMs) is performed through first-principles calculations based on density functional theory (DFT). The TMs considered herein include Sc, V, Fe, Co, Ni, Cu, Y, Zr, and Nb, which substitute for Mg at a doping concentration of 3.125% in both the hydrides. This insertion of TMs causes a variation in the cell volumes of - and -MgH2. The majority of the TM dopants decrease the lattice constants, with Ni resulting in the largest reduction. From the formation-energy calculations, it is predicted that except for Cu and Ni, the mixing of all the selected TM dopants with the MgH2 phases is exothermic. The selected TMs also influence the stability of both - and -MgH2 and cause destabilization by weakening the MgH bonds. Our results show that doping with certain TMs can facilitate desorption of hydrogen from - and -MgH2 at much lower temperatures than from their pure forms. The hydrogen adsorption strengths are also studied by density-of-states analysis.
|
|
