Combined First-Principles Molecular Dynamics/Density Functional Theory Study of Ammonia Electrooxidation on Pt(100) Electrode

Abstract

A combined first-principles molecular dynamics/density functional theory study of the electrooxidation of ammonia is conducted to gain an atomic-level understanding of the electrocatalytic processes at the Pt(100)/alkaline solution interface and to probe the mechanistic details of ammonia electrooxidation on the metal surface. A systematic study of adsorption and relative stability of ammonia and the intermediate species on the Pt(100) surface as a function of potential is carried out and activation energy profiles for the mechanistic steps in the ammonia oxidation are presented. The reaction mechanism is potential dependent: the modeling study supports the Oswin and Salomon’s mechanism for moderate surface potentials (≥+0.5 V vs RHE), and the Gerischer and Maurer’s mechanism for lower potentials (<+0.5 V vs RHE). The high electrocatalytic activity of Pt(100) is ascribed to the facile dimerization of bridging nitrogen atoms to form molecular nitrogen, whereas low activity of Pt(111) and Pt(110) is imputed to the nitrogen atoms that are strongly bound at hollow sites and poisoning the surface.

Enhanced Catalysis of Pt 3 Clusters Supported on Graphene for N–H Bond Dissociation

“…The most stable structure corresponds to NH 3 adsorption on the top site. 59,60 However, as the platinum particle size decreases, the bulk structure vanishes and the cluster morphology influences the adsorption behavior. We investigated the optimized configurations of *NH 3 adsorbed on several different sites of the supported Pt 13 clusters (shown in Supporting Information Figure S2).…”

Atomistic Insights into Nitrogen-Cycle Electrochemistry: A Combined DFT and Kinetic Monte Carlo Analysis of NO Electrochemical Reduction on Pt(100)

“…First, it is often the case that bond formation, in this case N-N bonds, can occur with lower overbarriers on the square lattice of the (100) surface as compared to the hexagonal (111) surface. [33][34][35] Second, Duca and coworkers showed that N 2 is a product of nitrate reduction through the NO* intermediate on the Pt(100) surface in alkaline media. 36 Those authors also proposed that the structure sensitivity is critical for the formation of N 2 via reaction of NO*+NH 2 *.…”

Multiscale Sampling of a Heterogeneous Water/Metal Catalyst Interface using Density Functional Theory and Force-Field Molecular Dynamics

“…We are particularly interested in heterogeneously catalyzed reactions that are carried out under liquid water. Water molecules have significant influence on catalytic phenomena, such as interacting with catalytic species (e.g., via dispersion forces and hydrogen bonding) 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23 , participating in catalytic reactions 1,7,8,9,15,21,22,24,25,26,27 , and influencing reaction pathways and/or catalytic rates 1,11,12,15,18,23,25,27,28,29,30,31 . Modeling of these phenomena has been performed using QM and/or ab initio molecular dynamics (AIMD) 1,2,…”