Comparative density functional theory study for predicting oxygen reduction activity of single-atom catalyst

It has been well established that nitrogen coordinated transition metal, TM-N$_{4}$-C (TM$=$Fe and Co) moieties, are responsible for the higher catalytic activity for the electrochemical oxygen reduction reaction. However, the results obtained using density functional theory calculations vary from one to another, which can lead to controversy. Herein, we assess the accuracy of the theoretical approach using different class of exchange-correlation functionals, i.e., Perdew-Burke-Ernzerhof (PBE) and revised PBE (RPBE), those with the Grimme's semiempirical dispersion correction (PBE+D3 and RPBE+D3), and the Bayesian error estimate functional with the nonlocal correlation (BEEF-vdW) on the reaction energies of oxygen reduction reaction on TM-N$_{4}$ moieties in graphene and those with OH-termination. We found that the predicted overpotentials using RPBE+D3 are comparable and consistent with those using BEEF-vdW. Our finding indicates that a proper choice of the exchange-correlation functional is crucial to a precise description of the catalytic activity of this system

Oxygen Reduction Reaction on Single-Atom Catalysts From Density Functional Theory Calculations Combined with an Implicit Solvation Model

We present a density functional theory study of the oxygen reduction reaction (ORR) on a single atom catalyst embedded in graphene, namely, TM-N$_{4}$-C (TM = Fe and Co), using the effective screening medium method combined with the reference interaction site model (ESM-RISM). It was found that Fe-N$_{4}$-C and Co-N$_{4}$-C show comparable ORR activities from the constant electrode potential simulations, in contrast to the results obtained using the constant (neutral) charge simulation, in which the superior performance of Co-N$_{4}$-C has been predicted. The constant potential method allows the variable charge and thus results in a potential dependence of the reaction-free energies different from that with the constant charge method in which the potential dependence is included as an ad hoc manner. We suggest the importance of the variable charge in the simulation of the electrochemical reaction, which is enabled by ESM-RISM

Self-limiting processes in thermal atomic layer etching of nickel by hexafluoroacetylacetone

Abdulrahman H. Basher, Ikutaro Hamada, and Satoshi Hamaguchi. Jpn. J. Appl. Phys. 59 090905

Theoretical Investigation of Hydrogen Desorption Process in Hydrogen Boride sheet for Catalytic Applications

大規模計算機システム利用者研究報

First Principles Study on Solid Oxygen Using Van der Waals Density Functional

We introduce scaling parameters for the spin-polarization dependent gradient correction to the local correlation in the van der Waals density functional, which enable us to tune the magnetic interaction between atoms and molecules. We have applied the method to solid oxygen and found that by using an optimal choice of the parameters, the structural parameters are significantly improved over the ones obtained in the previous work. We discuss the generic features of the proposed approach. © 2015 The Authors. Published by Elsevier B.V.20th International Conference on Magnetism, ICM 2015; Palau de Congressos de Catalunya679, Avinguda DiagonalBarcelona; Spain; 5 July 2015 through 10 July 201

Quantum Nuclei at Weakly Bonded Interfaces: The Case of Cyclohexane on Rh(111)

The electronic properties of interfaces can depend on their isotopic constitution. One known case is that of cyclohexane physisorbed on Rh(111), in which isotope effects have been measured on the work function change and desorption energies. These effects can only be captured by calculations including nuclear quantum effects (NQE). In this paper, this interface is addressed employing dispersion-inclusive density-functional theory coupled to a quasi-harmonic (QH) approximation for NQE, as well as to fully anharmonic ab initio path integral molecular dynamics (PIMD). The QH approximation is able to capture that deuterated cyclohexane has a smaller adsorption energy and lies about 0.01 A farther from the Rh(111) surface than its isotopologue, which can be correlated to the isotope effect in the work function change. An investigation of the validity of the QH approximation relying on PIMD simulations, leads to the conclusion that although this interface is highly impacted by anharmonic quantum fluctuations in the molecular layer and at bonding sites, these anharmonic contributions play a minor role when analysing isotope effects at low temperatures. Nevertheless, anharmonic quantum fluctuations cause an increase in the distance between the molecular layer and Rh(111), a consequent smaller overall work function change, and intricate changes in orbital hybridization.Comment: 24 pages and 6 figures in the main text, and 15 pages and 7 figures in the supplemental informatio