Theoretical Insights into Potential-Dependent C-C Bond Formation Mechanisms during CO Electroreduction into C Products on Cu(100) at Simulated Electrochemical Interfaces.

An improved CO coverage-dependent electrochemical interface model with an explicit solvent effect on Cu(100) is presented in this paper, by which theoretical insights into the potential-dependent C-C bond formation pathways occurring in CO electrochemical reduction to C products can be obtained. Our present studies indicate that CHO is a crucial intermediate toward C products on Cu(111), and dimer OCCO is found to not be a viable species for the production of C products on Cu(100). The reaction pathway of CHO with CO and CHO dimerization into dimers COCHO and CHOCHO may be C-C bond formation mechanisms at low overpotential. However, at medium overpotential, C-C bond coupling takes place preferentially through the reaction of COH with CO species and COH dimerization into dimers COCOH and COHCOH. The formed dimers COCHO, CHOCOH, and CHOCHO reactions of CHO with CO, COH, and CHO species may lead to C products, which are regarded as C-C bond formation mechanisms at high overpotential. The difference of obtained adsorption isotherms of CO on Cu(100) with that of Cu(111) may be able to explain the effect of the crystal face of Cu on product selectivity. The excellent consistencies between our present obtained conclusions and the available experimental reports and partial theoretical studies validate the reasonability of the present employed methodology, which can be also used to systematically study potential-dependent CO electroreduction pathways toward C products on Cu(100) or other metal catalysts.