Developing micro-kinetic model for electrocatalytic reduction of carbon dioxide on copper electrode

A micro-kinetic model combining electrochemical rate theory and first-principles simulation is developed to study the influences of solution pH and electrode potential on reaction rate, reaction pathways, and product distribution of electrocatalytic CO2 conversion. Two critical issues involved in electrochemical reaction mechanism are investigated: 1) competing concerted and sequential proton-electron transfer pathways, 2) competing thermodynamics-controlled and kinetics-controlled pathways. Our results show that the electrochemical reduction of CO2 to CO and HCOOH adopts a thermodynamics-controlled CPET mechanism at low pH, while follows a kinetics-controlled SPET mechanism at high pH. The electrocatalytic activity and selectivity can be effectively modulated by manipulating of solution pH and electrode potential. It is demonstrated that HCOOH is the main product at low overpotential while CO becomes the main product at high overpotential. In addition, increasing pH is conducive to improving the Faradic efficiency of HCOOH production and suppressing the hydrogen evolution reaction.