| 1. |
- Dobrota, Ana S., et al.
(författare)
-
Oxidized graphene as an electrode material for rechargeable metal-ion batteries - a DFT point of view
- 2015
-
Ingår i: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 176, s. 1092-1099
-
Tidskriftsartikel (refereegranskat)abstract
- In line with a growing interest in the use of graphene-based materials for energy storage applications and active research in the field of rechargeable metal-ion batteries we have performed a DFT based computational study of alkali metal atoms (Li, Na and K) interaction with an oxidized graphene. The presence of oxygen surface groups (epoxy and hydroxyl) alters the chemisorption properties of graphene. In particular, we observe that the epoxy groups are redox active and enhance the alkali metal adsorption energies by a factor of 2 or more. When an alkali metal atom interacts with hydroxyl-graphene the formation of metal-hydroxide is observed. In addition to a potential boost of metal ion storage capability, oxygen functional groups also prevent the precipitation of the metal phase. By simulating lithiation/de-lithiation process on epoxy-graphenes, it was concluded that the oxidized graphene can undergo structural changes during battery operation. Our results suggest that the content and the type of oxygen surface groups should be carefully tailored to maximize the performance of metal-ion batteries. This is mainly related to the control of the oxidation level in order to provide enough active centers for metal ion storage while preserving sufficient electrical conductivity.
|
|
| 2. |
- Pasti, Igor A., et al.
(författare)
-
Adsorption of nonmetallic elements on defect-free MgO(001) surface - DFT study
- 2015
-
Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 632, s. 39-49
-
Tidskriftsartikel (refereegranskat)abstract
- Adsorption of 11 non-metals (H, B, C, N, O, F, Si, P, S, Cl and Br) on defect-free MgO(001) surface was investigate using DFT approach. Adsorption energies were found to be between -0.56 eV (hydrogen adsorption) and -2.63 eV (carbon adsorption). Charge transfer from substrate to adsorbate was observed to follow the periodicity in the Periodic Table of Elements, as increases from left to right and decreases from top to bottom. All investigated adsorbates prefer oxygen sites on MgO surface. The analysis of adsorbate-MgO(001) electronic structure suggested that the electronic structure of the O adsorption center and adsorbate atom is molecule-like and there is no strong interaction with MgO electronic bands. Based on the obtained dataset for adsorption energies of selected non-metallic adsorbates (X) the reactivity of MgO towards the bond cleavage in the cases of X-X, H-X and HO-X bonds was discussed. Obtained results point to weak reactivity of MgO(001) towards atomic adsorption and low activity for bond cleavage. However, these results can be used as a starting point for the functionalization of MgO, particularly in the cases where bond cleavage activity and surface-mediated stabilization of dissociation products are desired.
|
|
| 3. |
- Pasti, Igor A., et al.
(författare)
-
Bimetallic dimers adsorbed on a defect-free MgO(001) surface : bonding, structure and reactivity
- 2015
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 17:15, s. 9666-9679
-
Tidskriftsartikel (refereegranskat)abstract
- A large number of computational studies have been devoted to the investigation of monometallic clusters supported by MgO. However, in practice, catalysis shows that multicomponent catalytic systems often win in catalytic performance over single component systems. In this study, the geometrical and electronic structure, stability and chemisorption properties of M1M2 metal dimers (M1, M2 = Ru, Rh, Pd, Ir, Pt) supported by defect free MgO(001) have been investigated in the framework of density functional theory. The oxygen sites of MgO(001) are the preferred adsorption sites for all the studied clusters, the majority of them adsorbing parallel to the surface with metal atoms attached to two surface oxygen atoms. The energetics of M1M2 + MgO(001) formation shows that the adsorption complexes are stable and benefit from metal-oxygen and metal-metal interaction. The chemisorption properties of Pd and Pt atoms in PdM2 and PtM2 dimers are studied using CO as a probe molecule. A linear relationship between the CO chemisorption and the d-band center position of the reacting atom in the dimer is observed, extending the d-band center model to the case of highly under-coordinated metal atoms supported by a non-conductive material.
|
|
| 4. |
- 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.
|
|
