A Perovskite Electronic Structure Descriptor for Electrochemical CO2 Reduction and the Competing H2 Evolution Reaction

Abstract

The electrochemical reduction of CO2 (CO2RR) to high-value products is an attractive means to simultaneously address the negative effects of increasing CO2 emissions and the ever-present societal demand for chemicals and fuels. However, the rational development of novel catalyst chemistries for this reaction is needed to tune the activity and selectivity of the CO2RR, especially for increasingly complex chemistries, such as oxides, sulfides, and phosphides. In this work, we explore a diverse chemical range of transition-metal perovskite oxides (ABO3) by determining their surface binding energies toward COads and Hads using density functional theory (DFT) and by evaluating their CO2RR activity and selectivity. We find that tuning perovskite chemistry results in the ability to electrochemically reduce CO2 to CH4. We propose the O 2p-band center as a rational design parameter that faithfully captures the energetics of Hads and COads binding that influence the hydrogen evolution reaction (HER) and CO2RR activity. A higher O 2p-band center results in higher HER activity, while an intermediate O 2p-band center improves favorability for CH4 evolution. In the process, we identify a group of perovskites (i.e., LaCoO3, GdCoO3, NdCoO3) as materials that have not, to date, been reported previously for CH4 evolution activity at relatively low overpotentials (−0.6 to −0.8 VRHE).