Engineering stable Cu+-Cu0 sites and oxygen defects in boron-doped copper oxide for electrocatalytic reduction of CO2 to C2+products

Cu-based catalysts inevitably undergo surface reconstruction during the electrochemical carbon dioxide reduction reaction (CO2RR) process. Thus, it is a challenge to construct stable Cu+-Cu0 sites of Cu-based catalysts. In this study, we report a simple and facile engineering strategy for stable Cu+-Cu0 sites and oxygen defects derived from the boron-doped copper composite catalyst (B-CuxO) as an efficient CO2RR electrocatalyst. The 5 % B-CuxO exhibited 48.44 % C2+ products Faraday efficiency (FE) for 12 h at -1.0 V vs reversible hydrogen electrode (RHE) in H-cell, which was far superior to CuxO (23.85 %). Combining density functional theory (DFT) and in situ Attenuated Total Reflection Fourier Transform Infrared spectroscopy (in situ ATR-FTIR), a higher electronic depletion on the catalyst surface inhibited the electrons accumulation around Cu sites, thereby maintaining the positive charge and inhibiting the complete reduction of Cu+. Moreover, the high oxygen defects in 5 % B-CuxO could effectively activate CO2 into *CO. We emphasized that Cu+ functioned as the primary active site by facilitating adsorption and dimerization of *CO, whereas Cu0 assisted in optimizing CO2 activation.