| 1. |
- Diklic, Natasa P., et al.
(författare)
-
Sodium storage via single epoxy group on graphene - The role of surface doping
- 2019
-
Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 297, s. 523-528
-
Tidskriftsartikel (refereegranskat)abstract
- Due to its unique physical and chemical properties, graphene is being considered as a promising material for energy conversion and storage applications. Introduction of functional groups and dopants on/in graphene is a useful strategy for tuning its properties. In order to fully exploit its potential, atomic-level understanding of its interaction with species of importance for such applications is required. We present a DFT study of the interaction of sodium atoms with epoxy-graphene and analyze how this interaction is affected upon doping with boron and nitrogen. We demonstrate how the dopants, combined with oxygen-containing groups alter the reactivity of graphene towards Na. Dopants act as attractors of epoxy groups, enhancing the sodium adsorption on doped oxygen-functionalized graphene when compared to the case of non-doped epoxy-graphene. Furthermore, by considering thermodynamics of the Na interaction with doped epoxy-graphene it has been concluded that such materials are good candidates for Na storage applications. Therefore, we suggest that controlled oxidation of doped carbon materials could lead to the development of advanced anode materials for rechargeable Na-ion batteries.
|
|
| 2. |
- Dobrota, Ana S., et al.
(författare)
-
A DFT study of the interplay between dopants and oxygen functional groups over the graphene basal plane - implications in energy-related applications
- 2017
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : ROYAL SOC CHEMISTRY. - 1463-9076 .- 1463-9084. ; 19:12, s. 8530-8540
-
Tidskriftsartikel (refereegranskat)abstract
- Understanding the ways graphene can be functionalized is of great importance for many contemporary technologies. Using density functional theory calculations we investigate how vacancy formation and substitutional doping by B, N, P and S affect the oxidizability and reactivity of the graphene basal plane. We find that the presence of these defects enhances the reactivity of graphene. In particular, these sites act as strong attractors for OH groups, suggesting that the oxidation of graphene could start at these sites or that these sites are the most difficult to reduce. Scaling between the OH and H adsorption energies is found on both reduced and oxidized doped graphene surfaces. Using the O-2 molecule as a probe we show that a proper modelling of doped graphene materials has to take into account the presence of oxygen functional groups.
|
|
| 3. |
- Dobrota, Ana S., et al.
(författare)
-
A general view on the reactivity of the oxygen-functionalized graphene basal plane
- 2016
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 18:9, s. 6580-6586
-
Tidskriftsartikel (refereegranskat)abstract
- In this contribution we inspect the adsorption of H, OH, Cl and Pt on oxidized graphene using DFT calculations. The introduction of epoxy and hydroxyl groups on the graphene basal plane significantly alters its chemisorption properties, which can be attributed to the deformation of the basal plane and the type and distribution of these groups. We show that a general scaling relation exists between the hydrogen binding energies and the binding energies of other investigated adsorbates, which allows for a simple probing of the reactivity of oxidized graphene with only one adsorbate. The electronic states of carbon atoms located within the 2 eV interval below the Fermi level are found to be responsible for the interaction of the basal plane with the chosen adsorbates. The number of electronic states situated in this energy interval is shown to correlate with hydrogen binding energies.
|
|
| 4. |
- Dobrota, Ana S., et al.
(författare)
-
Functionalized graphene for sodium battery applications : the DFT insights
- 2017
-
Ingår i: Electrochimica Acta. - : Elsevier. - 0013-4686 .- 1873-3859. ; 250, s. 185-195
-
Tidskriftsartikel (refereegranskat)abstract
- Considering the increasing interest in the use of graphene-based materials for energy conversion and storage applications, we have performed a DFT study of Na interaction with doped graphene, both in non-oxidized and oxidized forms. Oxidation seems to play the crucial role when it comes to the interaction of doped graphene materials with sodium. The dopants act as attractors of OH groups, making the material prone to oxidation, and therefore altering its affinity towards Na. In some cases, this can result in hydroxide or water formation - an irreversible change lethal for battery performance. Our results suggest that one should carefully control the oxidation level of doped graphene-based materials if they are to be used as sodium battery electrode materials as the optimal oxidation level depends on the dopant type.
|
|
| 5. |
- Dobrota, Ana S., et al.
(författare)
-
Stabilization of alkali metal ions interaction with OH-functionalized graphene via clustering of OH groups - implications in charge storage applications
- 2016
-
Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 6:63, s. 57910-57919
-
Tidskriftsartikel (refereegranskat)abstract
- Graphene synthesized by reduction of graphene oxide, depending on the degree of reduction, retains a certain amount of surface OH groups. Considering the surface OH groups/graphene layer system by means of density functional theory calculations, we evidenced the tendency of OH groups to cluster, resulting in enhanced system stability and no band gap opening. In the oxygen concentration range between 1.8 and 8.47 at%, with the addition of each new OH group, integral binding energy decreases, while differential binding energy shows the boost at even numbers of OH groups. Furthermore, we found that the clustering of OH groups over graphene basal plane plays a crucial role in enhancing the interactions with alkali metals. Namely, if alkali metal atoms interact with individual OH groups only, the interaction leads to an irreversible formation of MOH phase. When alkali atoms interact with clusters containing odd number of OH groups, a reversible transfer of an electron charge from the metal atom to the substrate takes place without OH removal. The strength of the interaction in general increases from Li to K. In an experimental investigation of a graphene sample which dominantly contains OH groups, we have shown that the trend in the specific interaction strength reflects to gravimetric capacitances measured in alkali metal chloride solutions. We propose that the charge stored in OH groups which interact with alkali metal cation and the pi electronic system of the graphene basal plane presents the main part of its pseudocapacitance.
|
|
| 6. |
- Fako, Edvin, et al.
(författare)
-
Lattice mismatch as the descriptor of segregation, stability and reactivity of supported thin catalyst films
- 2018
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : ROYAL SOC CHEMISTRY. - 1463-9076 .- 1463-9084. ; 20:3, s. 1524-1530
-
Tidskriftsartikel (refereegranskat)abstract
- The increasing demand and high prices of advanced catalysts motivate a constant search for novel active materials with reduced contents of noble metals. The development of thin films and core-shell catalysts seems to be a promising strategy along this path. Using density functional theory we have analyzed a number of surface properties of supported bimetallic thin films with the composition A(3)B (where A = Pt and Pd, and B = Cu, Ag and Au). We focus on the surface segregation, dissolution stability and surface electronic structure. We also address the chemisorption properties of Pd3Au thin films supported by different substrates, by probing the surface reactivity with CO. We find a strong influence of the support in the case of mono- and bilayers, while the surface strain seems to be the predominant factor in determining the surface properties of supported trilayers and thicker films. In particular, we show that the studied properties of the supported trilayers can be predicted from the lattice mismatch between the overlayer and the support. Namely, if the strain dependence of the corresponding quantities for pure strained surfaces is known, the properties of strained supported trilayers can be reliably estimated. The obtained results can be used in the design of novel catalysts and predictions of the surface properties of supported ultrathin catalyst layers.
|
|
| 7. |
- Gutic, Sanjin J., et al.
(författare)
-
Improved catalysts for hydrogen evolution reaction in alkaline solutions through the electrochemical formation of nickel-reduced graphene oxide interface
- 2017
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : ROYAL SOC CHEMISTRY. - 1463-9076 .- 1463-9084. ; 19:20, s. 13281-13293
-
Tidskriftsartikel (refereegranskat)abstract
- H-2 production via water electrolysis plays an important role in hydrogen economy. Hence, novel cheap electrocatalysts for the hydrogen evolution reaction ( HER) are constantly needed. Here, we describe a simple method for the preparation of composite catalysts for H-2 evolution, consisting in simultaneous reduction of the graphene oxide film, and electrochemical deposition of Ni on its surface. The obtained composites (Ni@rGO), compared to pure electrodeposited Ni, show an improved electrocatalytic activity towards HER in alkaline media. We found that the activity of the Ni@rGO catalysts depends on the surface composition ( Ni vs. C mole ratio) and on the level of structural disorder of the rGO support. We suggest that HER activity is improved via H-ads spillover from the Ni particles to the rGO support, where quick recombination to molecular hydrogen is favored. A deeper insight into such a mechanism of H-2 production was achieved by kinetic Monte-Carlo simulations. These simulations enabled the reproduction of experimentally observed trends under the assumption that the support can act as a Hads acceptor. We expect that the proposed procedure for the production of novel HER catalysts could be generalized and lead to the development of a new generation of HER catalysts by tailoring the catalyst/support interface.
|
|
| 8. |
- Pasti, Igor A., et al.
(författare)
-
Atomic adsorption on graphene with a single vacancy : systematic DFT study through the periodic table of elements
- 2018
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 20:2, s. 858-865
-
Tidskriftsartikel (refereegranskat)abstract
- Vacancies in graphene present sites of altered chemical reactivity and open possibilities to tune graphene properties by defect engineering. The understanding of chemical reactivity of such defects is essential for successful implementation of carbon materials in advanced technologies. We report the results of a systematic DFT study of atomic adsorption on graphene with a single vacancy for the elements of rows 1-6 of the periodic table of elements (PTE), excluding lanthanides. The calculations have been performed using the PBE, long-range dispersion interaction-corrected PBE (PBE+D2 and PBE+D3) and non-local vdW-DF2 functionals. We find that most elements strongly bind to the vacancy, except for the elements of groups 11 and 12, and noble gases, for which the contribution of dispersion interaction to bonding is most significant. The strength of the interaction with the vacancy correlates with the cohesive energy of the elements in their stable phases: the higher the cohesive energy is, the stronger bonding to the vacancy can be expected. As most atoms can be trapped at the SV site we have calculated the potentials of dissolution and found that in most cases the metals adsorbed at the vacancy are more "noble" than they are in their corresponding stable phases.
|
|
| 9. |
- Pasti, Igor A., et al.
(författare)
-
Theoretical studies in catalysis and electrocatalysis : from fundamental knowledge to catalyst design
- 2015
-
Ingår i: Reaction Kinetics, Mechanisms and Catalysis. - : Springer Science and Business Media LLC. - 1878-5190 .- 1878-5204. ; 115:1, s. 5-32
-
Tidskriftsartikel (refereegranskat)abstract
- Catalytic processes are an indispensable part of a large number of contemporary technologies that stimulate a constant research and development effort in the field. Computational methods represent a valuable tool to investigate crucial steps of catalytic cycles able to reveal the main characteristics of a catalyst and provide a basis for the design of materials with superior catalytic activity. This review is focused on the recent advances in density functional theory studies of the interactions of reactive species and intermediates with solid surfaces. As examples, we discuss the catalysts for the CO oxidation and electrocatalysis of H-2 and O-2 electrode reactions. We demonstrate how the theoretical modelling can contribute to the understanding of catalytic processes and help to design new catalysts and electrocatalysts.
|
|
| 10. |
- Dobrota, Ana S., et al.
(författare)
-
Altering the reactivity of pristine, N- and P-doped graphene by strain engineering : A DFT view on energy related aspects
- 2020
-
Ingår i: Applied Surface Science. - : ELSEVIER. - 0169-4332 .- 1873-5584. ; 514
-
Tidskriftsartikel (refereegranskat)abstract
- For carbon-based materials, in contrast to metal surfaces, a general relationship between strain and reactivity is not yet established, even though there are literature reports on strained graphene. Knowledge of such relationships would be extremely beneficial for understanding the reactivity of graphene-based surfaces and finding optimisation strategies which would make these materials more suitable for targeted applications. Here we investigate the effects of compressive and tensile strain (up to +/- 5%) on the structure, electronic properties and reactivity of pure, N-doped and P-doped graphene, using DFT calculations. We demonstrate the possibility of tuning the topology of the graphene surface by strain, as well as by the choice of the dopant atom. The reactivity of (doped) strained graphene is probed using H and Na as simple adsorbates of great practical importance. Strain can both enhance and weaken H and Na adsorption on (doped) graphene. In case of Na adsorption, a linear relationship is observed between the Na adsorption energy on P-doped graphene and the phosphorus charge. A linear relationship between the Na adsorption energy on flat graphene surfaces and strain is found. Based on the adsorption energies and electrical conductivity, potentially good candidates for hydrogen storage and sodiumion battery electrodes are discussed.
|
|
| 11. |
- Dobrota, Ana S., et al.
(författare)
-
Surface pourbaix plots of M@N-4-graphene single-atom electrocatalysts from density functional theory thermodynamic modeling
- 2022
-
Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 412
-
Tidskriftsartikel (refereegranskat)abstract
- Single-atom catalysts (SACs) are rapidly developing in various application areas, including electrocatalysis of different reactions, usually taking place under harsh pH/electrode potential conditions. Thus, a full atomic-level understanding of the nature of the active sites under realistic electrochemical conditions is needed, having in mind that the state of SACs active centers could be altered by the adsorption of spectating species. In this contribution, Density Functional Theory is employed to conduct thermodynamic analysis of SACs with metal atoms (Mn, Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, or Au) embedded into N4 moiety in graphene. Various surface electrochemical processes on such SACs are considered, their Pourbaix plots are constructed, and their activity, selectivity, and stability under operating conditions are discussed. It is demonstrated how adsorption of H, O and OH can cause blockage and restructuring of the active sites and alter the electronic structure. Furthermore, when one deals with metals with lower D-band filling, it is shown that metal center oxidation is preferred over the oxidation of carbon lattice. The effect of the state of the metal center on the reactivity of the carbon lattice is discussed in the case of Fe@N-4-graphene. Finally, a possible strategy for confirming the changes in the architecture of the SACs' active site by analyzing their vibration spectra is suggested.
|
|
| 12. |
- Dobrota, Ana S., et al.
(författare)
-
What Is the Real State of Single-Atom Catalysts under Electrochemical Conditions-From Adsorption to Surface Pourbaix Plots?
- 2021
-
Ingår i: Catalysts. - : MDPI AG. - 2073-4344. ; 11:10
-
Tidskriftsartikel (refereegranskat)abstract
- The interest in single-atom catalysts (SACs) is increasing, as these materials have the ultimate level of catalyst utilization, while novel reactions where SACs are used are constantly being discovered. However, to properly understand SACs and to further improve these materials, it is necessary to consider the nature of active sites under operating conditions. This is particularly important when SACs are used as electrocatalysts due to harsh experimental conditions, including extreme pH values or high anodic and cathodic potential. In this contribution, density functional theory-based thermodynamic modelling is used to address the nature of metal centers in SACs formed by embedding single metal atoms (Ru, Rh, Ir, Ni, Pd, Pt, Cu, Ag, and Au) into graphene monovacancy. Our results suggest that none of these SAC metal centers are clean at any potential or pH in the water thermodynamic stability region. Instead, metal centers are covered with H-ads, OHads, or O-ads, and in some cases, we observed the restructuring of the metal sites due to oxygen incorporation. Based on these findings, it is suggested that setting up theoretical models for SAC modelling and the interpretation of ex situ characterization results using ultra-high vacuum (UHV) techniques requires special care, as the nature of SAC active sites under operating conditions can significantly diverge from the basic models or the pictures set by the UHV measurements.
|
|
| 13. |
- Gavrilov, Nemanja, et al.
(författare)
-
A study of ordered mesoporous carbon doped with Co and Ni as a catalyst of oxygen reduction reaction in both alkaline and acidic media
- 2018
-
Ingår i: Surface & Coatings Technology. - : Elsevier. - 0257-8972 .- 1879-3347. ; 349, s. 511-521
-
Tidskriftsartikel (refereegranskat)abstract
- The incorporation of trace amounts (< 0.2%) of Co and Ni noticeably enhanced the catalytic activity of nitrogen free ordered mesoporous carbon (OMC) towards oxygen reduction reaction (ORR). (Co,Ni)-doped OMCs were characterized by N-2-adsorption measurements, X-ray powder diffraction, field emission scanning electron microscopy and Raman spectroscopy methods, and their ORR activity was estimated by voltammetry on rotating disk electrode in acidic and alkaline media. (Co,Ni)-doped OMCs show modest activities in acidic media, while the catalytic activity in alkaline media is rather high. The measured activities are compared to the Pt-based and Pt-free ORR catalysts reported in the literature. The number of electrons consumed per O-2 in metal-doped OMCs was found to vary between 2 and 4, which is advantageous in comparison to metal-free OMC. Also, the mass activities of metal-doped OMCs were found to be up to 2.5 times higher compared to that of metal-free OMC. We suggest that the ORR activity is governed by a balance between (i) textural properties, which determine the electrochemically accessible surface of the catalyst and which are influenced by the addition of a metal precursor, and (ii) novel active sites formed upon the introduction of metals into the carbon structure. In particular, our Density Functional Theory calculations suggest that Co and Ni atoms embedded into the single vacancies of graphene can activate the O-2 molecule and contribute to the decomposition of peroxide.
|
|
| 14. |
- Jovanovic, Aleksandar Z., et al.
(författare)
-
Enhancement of hydrogen evolution reaction kinetics in alkaline media by fast galvanic displacement of nickel with rhodium-From smooth surfaces to electrodeposited nickel foams
- 2022
-
Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 414
-
Tidskriftsartikel (refereegranskat)abstract
- Energy-efficient hydrogen production is one of the key factors for advancing hydrogen-based economy. Alkaline water electrolysis is the main route for the production of high-purity hydrogen, but further improvements of hydrogen evolution reaction (HER) catalysts are still needed. Industrial alkaline electrolysis relies on Ni-based catalysts, and here we describe a drastic improvement of HER activity of Ni in alkaline media using several model catalysts for HER, obtained upon nickel surface modification in the aqueous solution of rhodium salts, where a spontaneous deposition of rhodium takes place, based on the chemical displacement reaction 3Ni + 2Rh3+ = 3Ni2+ + 2Rh. In the case of smooth Ni-poly electrodes, HER activity surpasses the activity of Pt-poly after just 30 s of exchange with Rh. SEM analysis showed that Rh is uniformly distributed, and that surface roughness changes are lower than 10%, which is in agreement with the electrochemical measurements. Furthermore, XPS analysis has shown effective incorporation of Rh in the surface, while DFT calculations suggest that hydrogen binding is significantly weakened on the Rh-modified Ni surfaces. Such tuning of the hydrogen binding energy is seen as the main factor governing HER activity improvements. The same galvanic displacement protocols were employed for nickel foam electrodes and electrodeposited Ni on Ti mesh. In both cases, somewhat longer Rh exchange times are needed to obtain superior activities than for the smooth Ni surface, but within 10 min. HER overpotentials corresponding to -10 mA cm-2 for nickel foam and electrodeposited Ni electrodes, after modification with Rh, amounted to only -0.07 and -0.09 V, respectively. Thus, it is suggested that a fast spontaneous displacement of Ni with Rh could effectively boost HER in alkaline media with minor cost penalties with regards to energy saving in the electrolysis process.
|
|
| 15. |
- Karacic, Dalibor, et al.
(författare)
-
Electrochemical reduction of thin graphene-oxide films in aqueous solutions - Restoration of conductivity
- 2022
-
Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 410
-
Tidskriftsartikel (refereegranskat)abstract
- Graphene oxide finds applications in different fields of science, including energy conversion. Electrochemical reduction of graphene oxide (GO) significantly improves its conductivity. However, the kinetics of this process depends on the solvent, supporting electrolyte, pH, and numerous other factors. Most studies report the macroscopic views and ex-situ properties of reduced GO. To expand the knowledge about GO reduction, in this study, we used cyclic voltammetry (CV), simultaneous 2 points and 4 points resistance measurement (s24), conductive atomic force microscopy (AFM), and theoretical calculations. Using CV, we demonstrated that the choice of supporting electrolyte (KCl or LiCl) influences the potential range in which electrochemical GO reduction occurs. The activation energy of this process was estimated to be below 30 kJ mol(-1) in both electrolytes, being significantly lower than that required for thermal reduction of GO. Simultaneous in situ s24 resistance measurements suggest that GO films reach a highly conductive state at deep negative potentials, with an abrupt, irreversible switch from non-conductive to the conductive state. However, conductive AFM presents a more exact picture of this process: the reduction of GO films starts locally while the formed conductive islands grow during the reduction. This mechanism was confirmed by theoretical calculations indicating that the reduction starts on isolated oxygen-functional groups over the GO basal plane, while clustered OH groups are more difficult to reduce. The presented results can help in tailoring reduced GO for a particular electrochemical application by precisely controlling the reduction degree and percentage of the conductive area of the reduced GO films.
|
|
| 16. |
- Nedić Vasiljević, Bojana, et al.
(författare)
-
Galvanic displacement of Co with Rh boosts hydrogen and oxygen evolution reactions in alkaline media
- 2023
-
Ingår i: Journal of Solid State Electrochemistry. - : Springer Nature. - 1432-8488 .- 1433-0768. ; 27:7, s. 1877-1887
-
Tidskriftsartikel (refereegranskat)abstract
- The growing energy crisis put an emphasis on the development of novel efficient energy conversion and storage systems. Here we show that surface modification of cobalt by a fast galvanic displacement with rhodium significantly affects the activity towards hydrogen (HER) and oxygen evolution reactions (OER) in alkaline media. After only 20 s of galvanic displacement, the HER overpotential is reduced by 0.16 V and OER overpotential by 0.06 V. This means that the predicted water splitting voltage is reduced from 2.03 V (clean Co anode and cathode) to 1.81 V at 10 mA cm−2 (Rh-exchanged Co electrode). During the galvanic displacement process, the surface roughness of the Co electrode does not suffer significant changes, which suggests an increase in the intrinsic catalytic activity. Density Functional Theory calculations show that the reactivity of the Rh-modified Co(0001) surface is modified compared to that of the clean Co(0001). In the case of HER, experimentally observed activity improvements are directly correlated to the weakening of the hydrogen-surface bond, confirming the beneficial role of Rh incorporation into the Co surface. Graphical abstract: [Figure not available: see fulltext.].
|
|
| 17. |
- Novcic, Katarina A., et al.
(författare)
-
Theoretical analysis of doped graphene as cathode catalyst in Li-O-2 and Na-O-2 batteries - the impact of the computational scheme
- 2020
-
Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 354
-
Tidskriftsartikel (refereegranskat)abstract
- Understanding the reactions in M-O-2 cells (M = Li or Na) is of great importance for further advancement of this promising technology. Computational modelling can be helpful along this way, but an adequate approach is needed to model such complex systems. We propose a new scheme for modelling processes in M-O-2 cells, where reference energies are obtained from high-level theory, CCSD(T), while the interactions of reaction intermediates with catalyst surfaces are extracted from computationally less expensive DFT. The approach is demonstrated for the case of graphene-based surfaces as model catalysts in Li-O-2 and Na-O-2 cells using the minimum viable mechanism. B-doped graphene was identified as the best catalyst amongst considered surfaces, while pristine graphene performs poorly. Moreover, we show that the inclusion of dispersion corrections for DFT has a significant impact on calculated discharge and charge potentials and suggests that long-range dispersion interactions should always be considered when graphene-based materials are modelled as electrocatalysts. Finally, we offer general guidelines for designing new ORR catalysts for M-O-2 cells in terms of the optimization of the interactions of catalyst surface with reaction intermediates.
|
|
| 18. |
- Pasti, Igor A., et al.
(författare)
-
Atomic adsorption on pristine graphene along the Periodic Table of Elements - From PBE to non-local functionals
- 2018
-
Ingår i: Applied Surface Science. - : ELSEVIER SCIENCE BV. - 0169-4332 .- 1873-5584. ; 436, s. 433-440
-
Tidskriftsartikel (refereegranskat)abstract
- The understanding of atomic adsorption on graphene is of high importance for many advanced technologies. Here we present a complete database of the atomic adsorption energies for the elements of the Periodic Table up to the atomic number 86 (excluding lanthanides) on pristine graphene. The energies have been calculated using the projector augmented wave (PAW) method with PBE, long-range dispersion interaction corrected PBE (PBE+D2, PBE+D3) as well as non-local vdW-DF2 approach. The inclusion of dispersion interactions leads to an exothermic adsorption for all the investigated elements. Dispersion interactions are found to be of particular importance for the adsorption of low atomic weight earth alkaline metals, coinage and s-metals (11th and 12th groups), high atomic weight p-elements and noble gases. We discuss the observed adsorption trends along the groups and rows of the Periodic Table as well some computational aspects of modelling atomic adsorption on graphene.
|
|
| 19. |
- Pašti, Igor, et al.
(författare)
-
Atomically Thin Metal Films on Foreign Substrates : From Lattice Mismatch to Electrocatalytic Activity
- 2019
-
Ingår i: ACS Catalysis. - : AMER CHEMICAL SOC. - 2155-5435. ; 9:4, s. 3467-3481
-
Tidskriftsartikel (refereegranskat)abstract
- Electrocatalytic properties of materials are governed by the electronic structure, stability, and reactivity of the surface layer which is exposed to the electrolyte. Over the years, different strategies have been developed to tailor electrocatalyst surfaces but also to reduce the cost of these materials, which is the bottleneck for any practical application. When a very thin metallic layer, intended to serve as an electrocatalyst, is placed over a substrate, its configuration is influenced by the structure of the substrate due to lattice mismatch, while the electronic structure is affected due to the strain and the electronic effects of the support. This results in altered bonding within the electrocatalyst layer and the modification of its electronic properties when compared to the pure phase. In this contribution, we address the possibilities of theoretical prediction of surface properties of atomically thin electrocatalyst films formed over different substrates, focusing on the metal side of the electrified interface. While all these properties can be calculated quite easily using modern computational techniques (but used with care), most often based on density functional theory, we also address an attractive, fast screening possibility to estimate the properties of monometallic and multimetallic overlayers using small sets of calculations on model systems. We discuss how lattice mismatch between a substrate and an overlayer can be used to predict the properties of electrocatalytic films, limitations of such approach, and a possibility of deploying of large databases which enable rapid prescreening of different support/overlayer systems for various electrocatalytic applications.
|
|
