Mechanistic study on Cu-catalyzed CO2 electroreduction into CH4 at simulated low overpotentials based on an improved electrochemical model

Abstract

An improved CO coverage-dependent electrochemical model with explicit relaxed H₂O molecules used in CO₂ electroreduction is presented, which is firstly applied to Cu-catalyzed CO₂ electroreduction into CH₄ production at low overpotentials in this paper. The results show that the present defined CH₂O and CHOH pathways via common intermediates CHO and CH₂ may be able to occur parallelly at the present simulated low overpotential. The potential-limiting steps may be the formation of CO and its further electroreduction into CHO, which are considered as the origin of the observed experimentally high overpotential. The present study also explains why at electrochemical interfaces, only CH₄ is observed experimentally on the Cu surface rather than CH₃OH. The present results are found to be in excellent agreement with the available experimental data and partial theoretical analysis, further validating the rationality of the present employed methodology.