Operando Spectroscopic Investigation of a Boron-Doped CuO Catalyst and Its Role in Selective Electrochemical C-C Coupling

Partially positive-charged copper (Cu delta+) is known to boost the formation of highly valued multicarbon C2+ products during the electrochemical CO2 reduction reaction (CO2RR). In this work, we doped boron in copper oxide (B-CuO) to create Cu delta+ sites and studied two important aspects regarding the CO2 RR: (1) the direct observation of the CO reaction intermediate on the Cu delta+ surface and (2) the role of Cu delta+ in enhancing C2+ selectivity. Operando attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) showed that distinct CO intermediates were present on CuO and B-CuO surfaces during the CO2RR. We observed that multiple CO adsorption sites and strong adsorption of the CO intermediate on the Cu delta+ surface promote the C-C coupling reaction in B-CuO. As a result, we achieved a C2+ Faradaic efficiency of 62.1% at -0.62 V versus reversible hydrogen electrode on B-CuO. In contrast, only 48% was achieved at -0.6S V on the CuO catalyst.