Computational Investigation of Hydriding and Strain Effects on the Binding Energies of Electrochemical CO2RR and HER Intermediates

A two-step process, involving syngas production, has recently been suggested as a feasible strategy for resolving the limit to the selectivity that can be achieved by fuel production via the electrochemical carbon dioxide reduction reaction (CO2RR). In pursuit of finding the optimal phase, orientation, and strain conditions of a Pd substrate for syngas production, we investigate the effects of hydriding and strain on the binding energies (BEs) of CO2RR and hydrogen evolution reaction intermediates on the (111), (100), and (110) surfaces of Pd by using density functional theory calculations. The calculation results show that the BEs are weakened by hydriding, most significantly on the (111) surface, rendering it more energetically favorable for syngas production than the others at sufficiently negative potentials. It is also shown that PdH(100) can be more energetically favorable than PdH(111) under compressive strains at weakly negative potentials owing to the high strain susceptibilities of the *CO BEs on the surface. These results are explained in terms of the effects of hydriding and strain on the electronic structures of Pd surface atoms and adsorption-induced mechanical interactions.