Interface interaction in CuBi catalysts with tunable product selectivity for electrochemical CO2 reduction reaction

Abstract

Multi-componential catalyst design is an important strategy to boost electrochemical carbon dioxide reduction reaction (ECO2RR) performance. There still lacks an effective binary catalyst design to create an alternative opportunity of tuning the desiring product formation. Herein, we report a facile synthetic method of CuO/Bi(OH)3 anchored on carbon nanotubes (CNTs) by the two-step chemical hydrolysis in alkaline ethanol solution for ECO2RR. Bimetallic CuBi nanoparticles are demonstrated as electrocatalytical active centers. By varying the Cu:Bi atomic fraction, we report for the first time to tune the ECO2RR products selectivity from CO to formate. At −0.99 V vs. reversible hydrogen electrode (RHE), CuBi-#4 (YBi = 9.1%) and CuBi-#8 (YBi = 19.2%) exhibit the tunable CO and formate Faradaic efficiency (FE) as 60% and 96%, respectively, surpassing the monometallic counterpart in selectivity and activity. Small amount of Bi dramatically alters the catalytic behavior of Cu in CuBi-#4 by stabilizing the *COOH and weakening the binding strength of *CO to improve CO2-to-CO conversion. By further increasing Bi content, the CO2RR pathway is switched from *COOH to *OCHO, giving rise to a pronounced formate selectivity in CuBi-#8. This work highlights a new type of bimetallic catalyst to achieve the tunable products by fine composition design for the development of advanced catalyst and knowledge of mechanism.