Reducing carbon dioxide (CO2) into useful organic feedstock, artificial photosynthesis aims to relieve global warming and feedstock shortage using a single system. The inclusion of multi-carbon intermediates and products (C2+) can significantly impact the mechanistic models of CO2 reduction reactions (CO2RR). In the present study, we calculated the thermodynamic and kinetic information for the electrocatalytic network of CO2RR on the metallic copper (Cu) surface and substantiated the synthetic mechanisms of C2+ products. In our model, the solvent, electrolyte, and applied potential were all implemented using a combination of quantum mechanics, statistical mechanics, and electrostatics. We confirmed that the carbon chain of an intermediate can be propagated through an efficient carbon−carbon (C−C) coupling reaction between an adsorbed carbon monoxide (CO) or formyl (CHO) entity and an existing unsaturated surface species, and a hydrogen atom can be incorporated from water through a Heyrovsky mechanism. We identified multiple C1/C2 and C2/C3 branching points formed by the competition between C−C coupling and hydrogenation pathways and discovered free energy barriers leading to these branches of similar magnitude. As a result, the final yields of C2+ are primarily determined by the surface coverages and secondarily by the reaction barriers. Our results managed to predict some of the C1/C2 and C2/C3 selectivity observed from experimental measurements.&lt;gdiv&gt;&lt;/gdiv&gt;

Three-carbon products in artificial photosynthesis: A computational insight

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.