Molecular-level understanding of the WGS and reverse WGS reactions on Rh through hierarchical multiscale approach

TL;DR

This study employs a hierarchical multiscale approach combining semi-empirical and first-principles methods to elucidate the distinct molecular mechanisms of WGS and r-WGS reactions on Rh catalysts, revealing different dominant pathways.

Contribution

The paper introduces a hierarchical multiscale methodology that accurately captures the different reaction mechanisms of WGS and r-WGS on Rh, overcoming biases of traditional first-principles analyses.

Findings

WGS follows a carboxyl (COOH) mechanism

r-WGS proceeds via a redox (CO2 to CO + O) mechanism

Hierarchical approach enhances understanding of complex catalytic reactions

Abstract

Hierarchically combining semi-empirical methods and first-principles calculations we gain a novel and noteworthy picture of the molecular-level mechanisms that govern the water-gas-shift (WGS) and reverse water-gas-shift (r-WGS) reactions on Rh catalysts. Central to this picture is that the WGS and r-WGS follow two different dominant reaction mechanisms: WGS proceeds according to a carboxyl (COOH) mechanism, whereas r-WGS proceeds according to a redox (CO2 {\to} CO + O) mechanism. The obtained results furthermore underscore the danger of common first-principles analyses that focus on a priori selected dominant paths. Not restricted to such bias, our herein proposed hierarchical approach thus constitutes a promising avenue to properly transport and incorporate the ab initio predictive-quality to a new level of system complexity.