Electrocatalytic CO2 reduction enhanced by Sb doping in MOF-derived carbon-supported Bi-based materials

Amidst the myriad catalysts employed in the electrochemical reduction of CO2, bimetallic materials stand out for their augmented catalytic activity and product selectivity. Bismuth (Bi), recognized for its marked selectivity towards formic acid along with attributes of low toxicity, cost-effectiveness, and widespread accessibility, emerges as a highly promising candidate with extensive research underway. Nonetheless, the catalytic attributes of Sb/Bi bimetallic composite materials incorporating antimony (Sb) elements have received limited attention. This study presents a successful synthesis of carbon-supported Sb/Bi bimetallic composite materials via the MOF templating approach, followed by a comprehensive exploration of their electrocatalytic properties for CO2 reduction. The investigation underscores the predominant integration of Sb elements in alloy configuration within the catalytic matrix. Trace Sb doping (≤3.1 %) emerges as a means to effectively suppress the formation of *H species while concurrently promoting *OCHO species, leading to a substantial elevation in the formate selectivity of Bi-based materials. In contrast, excessive Sb doping, by exacerbating *H formation, inadvertently intensifies the HER process, thereby unfavorably influencing formate generation. Promisingly, in comparison to Bi@C materials, Sb/Bi@C materials doped with minute quantities of Sb showcase enhanced electrode stability and an extended catalytic lifespan within the context of electrochemical operating conditions, which can be attributed to the fact that the introduction of Sb can significantly strengthen the spherical physical structure of carbon-borne nanomaterials on the surface of Bi@C materials. Through an amalgamation of empirical characterization and DFT calculations, this inquiry elucidates the pivotal role assumed by Sb incorporation in Bi materials, consequently advancing the realm of CO2RR. The research emphasizes a strategy of phase and structure engineering, which can provide valuable insights for the development of high-performance electrocatalysts not only in CO2RR but also in other fields.