Electrochemical CO2 Reduction on Pd-Based Electrodes: From Mechanism Understanding to Rational Catalyst Design

Abstract

Electrochemical CO2 reduction reaction (CO2RR) driven by clean electricity to valuable chemicals provides a feasible way to carbon neutrality and thus attracts increasing attention. Among different transition-metal based CO2RR catalysts, Pd is the unique one because of the potential-dependent 2e− reduction products distribution tunable from formate to CO, as well as the interconversion between CO2 and HCOOH achieved at equilibrium potential only on Pd surfaces. Considering these advantages, this review summarizes recent research progresses on Pd catalyzed CO2RR in past 5 years, including new mechanism understanding on Pd surfaces, and rational design of Pd-based electrocatalysts. For mechanism studies, the reaction pathways, the adsorption configurations for formate intermediate, and the roles of adsorbed CO species have been discussed. For catalyst discovery, both monometallic Pd and Pd-based catalysts with secondary metal and metalloid elements are overviewed. At the end, we put forward the possibility of utilizing Pd-based catalysts in electrolyzers to bridge the fundamentals and applications.