Research PaperEnhancing CO2 electrolysis to formate on facilely synthesized Bi catalysts at low overpotential

- Micro-Bi45 catalyst was synthesized using a facile aqueous chemical reduction route.
- A Faradaic efficiency of 90% for CO2 reduction to formate was observed at −1.45 V vs. SCE.
- A Tafel slope of 112 mV/dec suggests an initial electron transfer to CO2 to form CO2− intermediate.
- Bi45 catalyst can provide more active sites due to enriched more (012) lattice planes.
- The Bi45/GDE electrode was stable over 20 h of continuous electrolysis operation.

The electrochemical reduction of CO2 to fuels and chemicals powered by renewable electricity has been regarded as a promising pathway, which can mitigate the greenhouse effect and energy crisis. However, the development of catalyst with high activity, selectivity, and good stability is still the bottleneck to accomplish this goal. In this communication, we report the promising performance of a micro-structured Bi catalyst which directly converts CO2 to fuels at room temperature and ambient pressure. The Bi catalyst is designed by a simple and facile aqueous chemical reduction strategy, which readily scales up. The Bi45 catalyst exhibits a superior catalytic activity for CO2 conversion to formate, achieving a high Faradic efficiency of 90% at applied potential −1.45 V vs. SCE. The overpotential for the Bi45/GDE electrode is only 600 mV, a new record to all reported Bi catalysts in the literature. Particularly, the catalyst proves to be robust without any obvious degradation over 20 h of continuous electrolysis at −1.45 V vs. SCE. The notable activity achieved here is ascribed to the special micro-structure of the Bi catalyst, which may afford more active sites, as indicated by comparison to the structure of commercial Bi.

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