Bismuth-oxygen moieties are beneficial for high-efficiency electrochemical CO2 reduction (CO2 RR) to produce formate; however, preserving bismuth-oxygen moieties while applying a cathodic potential is challenging. This work reports the preparation of ultrathin Bi2 O2 O/Bi2 O2 (OH)(NO3 ) nanosheets (BiON-uts) by in-situ tailoring of hydrogen bonds in a Bi2 O2 (OH)(NO3 ) precursor. The BiON-uts exhibits a formate faradaic efficiency of 98 % with higher partial current density than that of most reported bismuth-based catalysts. Mechanistic studies demonstrate that the ultrathin nanosheet morphology facilitates ion-exchange between BiON-uts and the electrolyte to produce Bi2 O2 CO3 as intermediate, and adsorption of CO2 with surface Bi2 O2 O. DFT calculations reveal that the rate-limiting first electron transfer is effectively improved by the high electron affinity of Bi2 O2 CO3 . More importantly, high-efficiency CO2 RR in turn protects the bismuth-oxygen moieties from being reduced and thus helps to maintain the excellent CO2 RR activity. This work offers an interactive mechanism of CO2 RR promotion and bismuth-oxygen moiety preservation, opening up new opportunities for developing high-performance catalysts.
Keywords: CO2 electroreduction; bismuth-oxygen moiety; hydrogen-bond tailoring; interactive mechanisms; ultrathin nanosheets.
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