Impact of hydrogen concentration for [formula omitted] reduction on [formula omitted]: A combination study of cluster expansion and kinetics analysis

Abstract

Pd hydride has shown better electrochemical CO2 reduction reaction (CO2RR) performance compared to metal Pd implying that H in the PdHx surface plays a vital role in affecting the performance. Using density functional theory (DFT) calculations in combination with active learning cluster expansion and Monte Carlo simulated annealing we identify 12 stable PdHx(111) configurations on the DFT convex hull and investigate the binding energies of intermediates in the CO2RR and the competing hydrogen evolution reaction. Through analysis of intermediate binding energies and a microkinetic model, we identify the atomic structures of the PdHx phase most likely to produce syngas. The high activity of the PdH0.6 surface can be attributed to the fact that H segregation in the PdHx(111) surface breaks the linear relation between HOCO* and CO* adsorbates.