Oxygen induced promotion of electrochemical reduction of CO2 via co-electrolysis

Ming He,Chunsong Li,Bingjun Xu,William A Goddard,Jingguang G Chen,Mu-Jeng Cheng,Xiaoxia Chang,Haochen Zhang,Qi Lu

doi:10.1038/s41467-020-17690-8

Abstract

Harnessing renewable electricity to drive the electrochemical reduction of CO2 is being intensely studied for sustainable fuel production and as a means for energy storage. Copper is the only monometallic electrocatalyst capable of converting CO2 to value-added products, e.g., hydrocarbons and oxygenates, but suffers from poor selectivity and mediocre activity. Multiple oxidative treatments have shown improvements in the performance of copper catalysts. However, the fundamental underpinning for such enhancement remains controversial. Here, we combine reactivity, in-situ surface-enhanced Raman spectroscopy, and computational investigations to demonstrate that the presence of surface hydroxyl species by co-electrolysis of CO2 with low concentrations of O2 can dramatically enhance the activity of copper catalyzed CO2 electroreduction. Our results indicate that co-electrolysis of CO2 with an oxidant is a promising strategy to introduce catalytically active species in electrocatalysis.

Highlights

Harnessing renewable electricity to drive the electrochemical reduction of CO2 is being intensely studied for sustainable fuel production and as a means for energy storage
There is a general recognition of the beneficial effect of oxidative treatments on Cu-based catalysts in the CO2 reduction reaction (CO2RR), the mechanisms through which the enhancement is realized remain a topic of considerable discussion
A much less discussed, but arguably more important, aspect is whether the oxidized Cu species, if they exist at the CO2RR conditions, contribute to enhanced reactivity of Cu-based catalysts after oxidative treatments

Summary

Introduction

Harnessing renewable electricity to drive the electrochemical reduction of CO2 is being intensely studied for sustainable fuel production and as a means for energy storage. It is conceivable that Cu oxide and/or hydroxide species are mere spectators during the CO2RR, while preferentially exposed facets or defects, e.g., located at the grain boundaries on the metallic Cu surface, induced by the treatment are the real cause of change in the catalytic performance[22,23,24,25]. This has been shown in our recent work in the CO-reduction reaction on Cu26. We demonstrate that the production rate of oxygenates and hydrocarbons in the CO2RR is enhanced by up to 216-fold when coupled with the oxygen reduction reaction (ORR)

Methods

Results

Conclusion