Theoretical Insights into the NH3 Decomposition Mechanism on the Cu- and Pt- Embedded Graphene Surfaces: A DFT Approach

Abstract

Herein, the catalytic activities of Cu-and Pt-embedded graphene surfaces on the sequential decomposition reaction of NH3 molecule were investigated by density functional theory (DFT). Partial charge changes on the surfaces by embedding Cu and Pt atoms on the bare graphene surface were analyzed by the Bader charge analysis and depicted by the electron density difference maps. Grimme-D2 dispersion correction was employed for weak interactions between adsorbates and both graphene surfaces. The most stable geometries of the adsorption of NHx (x = 0 -> 3) and H species and their fragmented co-adsorption structures on both graphene surfaces were obtained. The internal energy barrier calculations required for the sequential decomposition of NH3 on both graphene surfaces were calculated by the CINEB method and the results obtained for complete decomposition of NH3 were illustrated by relative energy diagram. The findings revealed that the decomposition of NH3 to NH2, NH, and N on the Cu-embedded graphene surface had relatively lower activation barriers of 1.52 eV, 0.72 eV, and 0.64 eV, respectively, compared to the Pt-embedded graphene surface. The Cu-embedded graphene surface was of high selectivity over the NH3 sequential decomposition reaction. This information may paw the way for different strategies for the development of Cu-based catalysts for NH3 decomposition. (C) 2021 The Electrochemical Society (ECS). Published on behalf of ECS by IOP Publishing Limited.