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Summary: The extension of low‐expense and stable electrocatalysts for oxygen reduction reaction (ORR) is of importance to improve the performance of metal‐air batteries and fuel cells. In this work, we unravel the ORR electrocatalytical mechanisms on a series of transition metal atom‐doped on the defect graphene (TM@sv‐graphene) by carrying out spin‐polarized first‐principles computations. The formation energy of the TM@sv‐graphene, which is related to its stability, along with the binding energy of O2, OOH, 2OH, OH, and O species are evaluated. The calculations of Gibbs free energy show that two different pathways, O* mechanism and 2OH* mechanism, of ORR compete with each other based on the structures of intermediates (OOH, 2OH, OH and O). It is found that Co, Rh, Ir, Pt, and Mn@sv‐graphene favor the O* mechanism while Ag, Au, Cd, Cu, Zn, Fe, Ni, Pd, Sc, Cr, Ti, Zr, and V@sv‐graphene strongly promote the 2OH* mechanism. The overpotential (η) of the ORR is predicted and can be a valid descriptor that manifests the catalytic activity of different TM@sv‐graphene. Among these catalysts, the Pd@sv‐graphene (η = 1.20 V) exhibits the best activity for the ORR. The results provide new insight into electrochemical mechanism of ORR for novel single‐atom electrocatalyst. [ABSTRACT FROM AUTHOR]

The catalytic activity for the adsorption and dehydrogenation of alkanes (CnH2n+2, n = 2, 3, 4) on a low-symmetry Rh13 cluster (Rh13-Ls) is compared with a system consisting of the same cluster (Rh13-Ls) supported on either an unzipped graphene-oxide (UGO) sheet (Rh13-Ls/UGO) or a TiO2(110) surface (Rh13-Ls/TiO2). The adsorption energies of these alkanes, calculated using density-functional theory, follow the order Rh13-Ls/TiO2≈ Rh13-Ls/UGO ＞ Rh13-Ls. Our proposed reaction path for the dehydrogenation of ethane, propane and butane on Rh13-Ls/UGO has first barrier heights of 0.21, 0.22 and 0.16 eV for the dissociation of a terminal C–H bond to form –C2H5, –C3H7 and –C4H9, respectively. Compared with the barriers on Rh13-Ls and Rh13-Ls/TiO2, the barrier on Rh13-Ls/UGO is the lowest for all alkanes. The calculated data, including the electronic distribution and the density of states of alkanes adsorbed on Rh13-Ls/UGO, Rh13-Ls and Rh13-Ls/TiO2, to support our results are presented. [ABSTRACT FROM AUTHOR]

Abstract: We have used spin-polarized density functional theory to investigate the adsorption and dissociation of N2O molecule on Fe(111) surface. Several adsorption geometries and sites were examined in detail. In our computational results, the Fe–N2O–η 2-[Nt(1,2), Ot(1)] exhibited the greatest adsorption energy, 1.16eV, on Fe(111) surface, whereas the other binding modes still have effective adsorption and dissociation behaviors. For the N2O dissociation mechanisms, our calculated results indicate that the most favorable pathway is the production of N2 +O fragments on the Fe(111) surface. Formation of NO+N is also possible, although this pathway involves a higher energy barrier. [Copyright &y& Elsevier]

Abstract: The rate-determining step of βC–H bond scission of ethanol dehydrogenation on Ru/ZrO2 and clean ZrO2 surfaces are investigated. This barrier is greater by 48.40kcal/mol on ZrO2 surface than that on Ru/ZrO2 counterpart. Deposition of Ru atoms on the ZrO2 surface greatly increases the catalytic performance. We calculate density of states and deformation energies of adsorbates and find out that the relative stability depends not only on the surface restructuring, but also on the interaction between surface and adsorbates. The catalytic role of deposited Ru is analyzed. [ABSTRACT FROM AUTHOR]

We applied periodic density-functional theory to investigate the interaction of NOxon Ni(111) surface for small and large coverages. For a small coverage, adsorbed species, such as NO, N2O and NO2, tend to dissociate to form atomic N and atomic O on the surface, but a large barrier, 2.34 eV, hinders the recombination of adsorbed N to form N2. At a large coverage, the recombination of N and NO to form N2O is favorable; this species might either desorb or break the N–O bond to form N2. Our calculated results agree satisfactorily with experimental observations. The formation of N2viapaths that vary with coverage is analyzed and discussed. [ABSTRACT FROM AUTHOR]

The catalytic activity for the adsorption and dehydrogenation of alkanes (C n H 2n+2 , n = 2, 3, 4) on a low-symmetry Rh 13 cluster (Rh 13 -L s ) is compared with a system consisting of the same cluster (Rh 13 -L s ) supported on either an unzipped graphene-oxide (UGO) sheet (Rh 13 -L s /UGO) or a TiO 2 (110) surface (Rh 13 -L s /TiO 2 ). The adsorption energies of these alkanes, calculated using density-functional theory, follow the order Rh 13 -L s /TiO 2 ≈ Rh 13 -L s /UGO > Rh 13 -L s . Our proposed reaction path for the dehydrogenation of ethane, propane and butane on Rh 13 -L s /UGO has first barrier heights of 0.21, 0.22 and 0.16 eV for the dissociation of a terminal C-H bond to form -C 2 H 5 , -C 3 H 7 and -C 4 H 9 , respectively. Compared with the barriers on Rh 13 -L s and Rh 13 -L s /TiO 2 , the barrier on Rh 13 -L s /UGO is the lowest for all alkanes. The calculated data, including the electronic distribution and the density of states of alkanes adsorbed on Rh 13 -L s /UGO, Rh 13 -L s and Rh 13 -L s /TiO 2 , to support our results are presented.