Optimizing Bi active sites by Ce doping for boosting formate production in a wide potential window

Abstract

The electrochemical carbon dioxide reduction reaction (CO₂RR) is considered as one of the sustainable and economical strategies for carbon utilization to effectively control the greenhouse effect and alleviate the rapid consumption of fossil fuels. In this work, metal–organic framework (MOF)-derived Ce-doped Bi@C nanorod (NR) electrocatalysts are facilely prepared through the pyrolysis method. Benefitting from Ce doping, the electron density around Bi active sites increases and the Bi–Bi bond length shortens, leading to stabilized reaction intermediates, a lower energy barrier towards *OCHO formation, faster electron transfer, and improved CO₂ adsorption. As a result, Ce_0.05Bi_0.95@C NRs show desirable faradaic efficiencies (FE) of over 90% towards formate formation in a wide potential window from −0.9 to −1.9 V_{vs. RHE} in an H-type cell, with the maximum value of 96.1%. Owing to the good intrinsic electrocatalytic activity, a high throughput performance of formate production is achieved with a FE of over 90% under high current density in a potential range as wide as 1100 mV, demonstrating the great potential of Ce-doped Bi@C NRs for practical CO₂RR applications.