| 1. |
- Li, Hu, 1986-, et al.
(författare)
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Fabrication of BP2T functionalized graphene via non-covalent π-π stacking interactions for enhanced ammonia detection
- 2021
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Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 11:57, s. 35982-35987
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Tidskriftsartikel (refereegranskat)abstract
- Graphene has stimulated great enthusiasm in a variety of fields, while its chemically inert surface still remains challenging for functionalization towards various applications. Herein, we report an approach to fabricate non-covalently functionalized graphene by employing pi-pi stacking interactions, which has potentialities for enhanced ammonia detection. 5,5 '-Di(4-biphenylyl)-2,2 '-bithiophene (BP2T) molecules are used in our work for the non-covalent functionalization through strong pi-pi interactions of aromatic structures with graphene, and systematic investigations by employing various spectroscopic and microscopic characterization methods confirm the successful non-covalent attachment of the BP2T on the top of graphene. From our gas sensing experiments, the BP2T functionalized graphene is promising for ammonia sensing with a 3-fold higher sensitivity comparing to that of the pristine graphene, which is mainly attributed to the enhanced binding energy between the ammonia and BP2T molecules derived by employing the Langmuir isotherm model. This work provides essential evidence of the pi-pi stacking interactions between graphene and aromatic molecules, and the reported approach also has the potential to be widely employed in a variety of graphene functionalizations for chemical detection.
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| 2. |
- Murugesan, Chinnasamy, et al.
(författare)
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Cobalt tetraphosphate as an efficient bifunctional electrocatalyst for hybrid sodium-air batteries
- 2021
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Ingår i: Nano Energy. - : Elsevier BV. - 2211-2855 .- 2211-3282. ; 89
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Tidskriftsartikel (refereegranskat)abstract
- Economic and efficient bifunctional electrocatalysts are pivotal in realization of rechargeable (hybrid) metal-air batteries. It is ideal to employ noble-metal free bifunctional electrocatalysts that are not selective towards oxygen evolution and reduction (OER and ORR) activities. This work unveils cobalt-based tetraphosphate K2Co(PO3)(4) as an economic bifunctional electrocatalyst acting as cathode for rechargeable hybrid sodium-air batteries. Auto combustion route led to the development of homogeneous, carbon-coated, spherical K2Co(PO3)(4) nanoparticles enabling active site exposure to incoming guest molecules (O-2, OH-). This monoclinic compound exhibited superior oxygen evolution activity with low overpotential (ca. 0.32 V) surpassing the commercial RuO2 catalyst. Tetraphosphate K2Co(PO3)(4) was successfully implemented in hybrid Na-air batteries delivering reversible cycling with roundtrip efficiency over 70%. DFT study revealed this catalytic activity stem from the most active and stable surface (001) and half-metallic nature of Co in K2Co(PO3)(4). Cobalt tetraphosphates can be harnessed to design low cost electrocatalysts for hybrid sodium-air batteries.
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| 3. |
- Wani, Ishtiaq Hassan, 1985-, et al.
(författare)
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A sub 20 nm metal-conjugated molecule junction acting as a nitrogen dioxide sensor
- 2019
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3364 .- 2040-3372. ; 11:14, s. 6571-6575
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Tidskriftsartikel (refereegranskat)abstract
- The interaction of a gas molecule with a sensing material causes the highest change in the electronic structure of the latter, when this material consists of only a few atoms. If the sensing material consists of a short, conductive molecule, the sensing action can be furthermore probed by connecting such molecules to nanoelectrodes. Here, we report that NO2 molecules that adhere to 4,4'-biphenyldithiol (BPDT) bound to Au surfaces lead to a change of the electrical transmission of the BPDT. The related device shows reproducible, stable measurements and is so far the smallest (<20 nm) gas sensor. It demonstrates modulation of charge transport through molecules upon exposure to nitrogen dioxide down to concentrations of 55 ppb. We have evaluated several devices and exposure conditions and obtained a close to linear dependence of the sensor response on the gas concentration.
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| 4. |
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| 5. |
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| 6. |
- Abdel-Hafiez, Mahmoud, et al.
(författare)
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Pressure-induced reentrant transition in NbS3 phases : Combined Raman scattering and x-ray diffraction study
- 2019
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Ingår i: Physical Review B. - : AMER PHYSICAL SOC. - 2469-9950 .- 2469-9969. ; 99:23
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Tidskriftsartikel (refereegranskat)abstract
- We report the evolution of charge density wave states under pressure for two NbS3 phases: triclinic (phase I) and monoclinic (phase II) at room temperature. Raman and x-ray diffraction (XRD) techniques are applied. The x-ray studies on the monoclinic phase under pressure show a compression of the lattice at different rates below and above similar to 7 GPa but without a change in space group symmetry. The Raman spectra of the two phases evolve similarly with pressure; all peaks almost disappear in the similar to 6-8 GPa range, indicating a transition from an insulating to a metallic state, and peaks at new positions appear above 8 GPa. The results suggest suppression of the ambient charge-density waves and their subsequent recovery with new orderings above 8 GPa.
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| 7. |
- Ahmadivand, Arash, et al.
(författare)
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Terahertz plasmonics : The rise of toroidal metadevices towards immunobiosensings
- 2020
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Ingår i: Materials Today. - : ELSEVIER SCI LTD. - 1369-7021 .- 1873-4103. ; 32, s. 108-130
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Forskningsöversikt (refereegranskat)abstract
- This work reviews fundamentals and the recent state-of-art achievements in the field of plasmonic biosensing based terahertz (THz) spectroscopy. Being nonpoisonous and nondestructive to the human tissues, THz signals offer promising, cost-effective, and real-time biodevices for practical pharmaco-logical applications such as enzyme reaction analysis. Rapid developments in the field of THz plasmonics biosensors and immunosensors have brought many methodologies to employ the resonant subwavelength structures operating based on the fundamental physics of multipoles and asymmetric lineshape resonances. In the ongoing hunt for new and advanced THz plasmonic biosensors, the toroidal metasensors have emerged as excellent alternates and are introduced to be a very promising technology for THz immunosensing applications. Here, we provide examples of recently proposed THz plasmonic metasensors for the detection of thin films, chemical and biological substances. This review allows to compare the performance of various biosensing tools based on THz plasmonic approach and to understand the strategic role of toroidal metasensors in highly accurate and sensitive biosensors instrumentation. The possibility of using THz plasmonic biosensors based on toroidal technology in modern medical and clinical practices has been briefly discussed.
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| 8. |
- Ahmadivand, Arash, et al.
(författare)
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Toroidal Metaphotonics and Metadevices
- 2020
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Ingår i: Laser & Photonics reviews. - : WILEY-V C H VERLAG GMBH. - 1863-8880 .- 1863-8899. ; 14:11
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Forskningsöversikt (refereegranskat)abstract
- Toroidal moments in artificial media have received growing attention and considered as a promising framework for initiating novel approaches to manage intrinsic radiative losses in nanophotonic and plasmonic systems. In the past decade, there has been substantial attention on the characteristics and excitation methods of toroidal multipoles-in particular, toroidal dipole-in 3D bulk and planar metaplatforms. The remarkable advantages of toroidal resonances have thrust the toroidal metasurface technology from relative anonymity into the limelight, in which researchers have recently centered on developing applied optical and optoelectronic subwavelength devices based on toroidal metaphotonics and metaplasmonics. In this focused contribution, the key principles of 3D and flatland toroidal metastructures are described, and the revolutionary tools that have been implemented based on this topology are briefly highlighted. Infrared photodetectors, immunobiosensors, ultraviolet beam sources, waveguides, and functional modulators are some of the fundamental and latest examples of toroidal metadevices that have been introduced and studied experimentally so far. The possibility of the realization of strong plexciton dynamics and pronounced vacuum Rabi oscillations in toroidal plasmonic metasurfaces are also presented in this review. Ultimate efficient extreme-subwavelength scale devices, such as low-threshold lasers and ultrafast switches, are thus in prospect.
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| 9. |
- Allal, Adel, et al.
(författare)
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A comparative theoretical investigation of optoelectronic and mechanical properties of KYS2 and KLaS2
- 2020
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Ingår i: Materials Science in Semiconductor Processing. - : Elsevier BV. - 1369-8001 .- 1873-4081. ; 113
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Tidskriftsartikel (refereegranskat)abstract
- The ternary sulfides KYS2 and KLaS2 are two promising candidates for numerous applications, as much as white LED, X-ray phosphor and transparent conductor materials. However, theoretical studies on these materials are lacking, and many of their physical properties are still unknown. The aim of this work is to investigate the physical properties of the ternary sulfides KYS2 and KLaS2 namely, structural, elastic, optoelectronic, thermodynamic analysis, and set the substitution effect of Y and La elements in the two compounds. The fundamental properties calculations are based on ab-initio pseudopotential framework, with both local density approximation (LDA) and generalized gradient approximations (GGA) along with an expanded set of plane waves. The Becke, 3-parameter, Lee–Yang–Parr (B3LYP) hybrid functional is also employed to describe the electronic structures and optical properties. The optimized crystal parameters are correlated very well with the existing experimental data. The predicted values of the elastic constants demonstrate that the two compounds are mechanically stable and can be classified as brittle materials. The band structure analysis reveals that both KYS2 and KLaS2 have indirect band gap. The optical properties, like the refractive index, extinction, absorption and reflectivity coefficients, are determined for various polarizations of incident light, while both compounds present optical anisotropy. The obtained optical properties indicate the high transparency of KYS2 and KLaS2 in the infrared and visible regions, which makes them promising candidates for many of transparent applications. The thermodynamic properties are investigated with the help of quasiharmonic Debye model approximation. KYS2 has a larger bulk modulus value, which make it more beneficial in engineering applications. Calculations of thermodynamical properties indicate that KYS2 compound has better thermal conductivity, stronger chemical bonds and bigger hardness.
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| 10. |
- Allal, Adel, et al.
(författare)
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Phase stability, phonon, electronic, and optical properties of not-yet-synthesized CsScS2, CsYS2, and APmS(2) (A= Li, Na, K, Rb, Cs) materials : Insights from first-principles calculations
- 2022
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Ingår i: Materials Science in Semiconductor Processing. - : Elsevier. - 1369-8001 .- 1873-4081. ; 150
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Tidskriftsartikel (refereegranskat)abstract
- Transparent conducting materials (TCMs) combine two exclusive properties, electrical conductivity and visible light transparency; which make them a unique class of materials. They are required in a wide range of applications in modern life ranging from touchscreen-based devices, flat panel displays, light-emitting diodes (LED), and solar cells. Most of the commercially and widely used TCMs are n-type, whereas the development of highperformance p-type TCMs remains an outstanding challenge in the actual time. Herein, using the newly developed SCAN meta-GGA and the hybrid HSE06 functionals, we have explored the structural stability and physical properties of not-yet-synthesized ternary materials CsScS2, CsYS2, and APmS(2) (A = Li, Na, K, Rb, Cs) to identify promising p-type TCMs. As result, the calculated formation energy, phase diagram and phonon dispersion curves confirm that these materials are thermodynamically stable and feasible to synthesize experimentally. All these materials, have large optical band gaps (larger than 3.4 eV), small hole effective masses (except for LiPmS2), and have no absorption and weak reflectivity of the visible light. Our work demonstrates that these compounds have suitable properties for p-type TCMs applications.
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