Density functional theory studies on electrochemical CO2 activation pathways under solvation effect

Abstract

For the mitigation of global warming problems and sustainable development of inevitable carbon based economy, carbon dioxide (CO2) conversion technology has been regarded as one of the most important and urgent scientific issues nowadays. Among various on-going attempts categorized as biochemical, thermochemical, electrochemical, and photo-assisted electrochemical processes, electrochemical CO2 conversion method has been drawn much attention due to its high reactivity at ambient condition and extensibility of small to large scale processes. Many researchers have extensively studied on electrochemical conversion of CO2 into various useful chemicals by using heterogeneous or homogeneous catalysts in aqueous or organic medium. However, it still requires more improvements in aspects of energetic efficiencies, catalytic stability, and current density to encourage practical application. In this work, by using density functional theory, we have focused on explication and optimization of the electrochemical CO2 reduction to CO as well as the effect of solvent dielectric characteristics on CO2 reduction pathway along with oxygen reduction reactions (ORRs). From the quantum mechanical thermodynamic energetics of electrochemical reduction of CO2 including solvation effect, we were able to design and propose effective electrochemical catalytic systems for highly selective CO production with minimized overpotential successfully. We have chosen monatomic doping on pure metal surface as a feasible strategy. Among the various dopants, d-block metal dopants have a weak effect on optimizing energetics due to their dominating d-band states. It turned out that p-block dopants have a significant effect on distinguish COOH radical and CO binding characters, as a result, sulfur, silicon, aluminum, and arsenic dopants are the most effective dopants to minimize the overpotential by specifically stabilizing COOH radical intermediate. Also, we discover the effect of dielectric constant ...