Scalable preparation of a CuO nanosheet array via corrosion engineering for selective C-C coupling in CO2 electroreduction

So far, copper (Cu) has been the only monometallic catalyst with substantial selectivity and productivity for the electrochemical CO2 reduction reaction (ECO2RR) to produce C2+ products. However, there still remains an enormous challenge to prepare highly efficient Cu electrodes on a large scale for industrial application. Additionally, further understanding of the structure-activity relationship of electrodes used in the ECO2RR is significantly important but lacking for the design of efficient Cu electrodes. Herein, we report a scalable preparation of a CuO nanosheet array on a Cu substrate via a facile corrosion engineering strategy. By tuning the surface roughness via controlling the corrosion time, we achieved a high faradaic efficiency (FE) for C2+ products (63.93% in an H-type cell, 70% in a flow cell) in the ECO2RR. In addition, the electrode showed a high selectivity exceeding 80% for C2+ products toward the electrochemical CO reduction reaction (ECORR). Moreover, we elucidate the structure-activity relationship of the CO2RR electrodes using our electrodes as a model, where both high active site density and moderate surface roughness are required simultaneously for an efficient CO2RR electrode, which would inspire future related studies.