Hydroxide-Oxide-Sulfur-Stabilized Bismuth Nanorod Conversion: Selective Induction of the Electrochemical Reduction of CO2 to Formate

The electrochemical CO₂ reduction reaction (e-CO₂RR) converts value-added chemicals into formate. Bismuth-based resources exhibit promising potential in the electrochemical reduction of CO₂ to formate due to their low toxicity and ability to enhance the *OCHO intermediate reaction pathway. However, there are numerous hurdles to optimizing their activity and applicability. Here, we describe the assembly of structurally stable bismuth hydroxide, oxide, and sulfide nanorods supported by a reduced graphene oxide (rGO) nanosheet through a simple hydrothermal method. The obtained optimized rGO-Bi₂S₃ nanorods exhibit improved e-CO₂RR conversions to formate in H-cell systems compared to hydroxide and oxide electrocatalysts. The rGO-Bi₂S₃ nanorods maintain high activity within a wide potential window (−0.76 to −1.26 V vs RHE) to obtain overall Faradaic efficiency of formate of ±84% at −1.16 V vs RHE, current density of formate of ±41.50 mA cm^–2, and stability for longer than 12 h, with improved Faradaic efficiency greater than ±86% in an H-cell system. Theoretical calculations reveal that the strong interaction between rGO and Bi₂S₃ stabilizes the adsorption of formate in e-CO₂RR. The resulting structural transformation of bismuth nanorods based on sulfur, oxide, and hydroxide provides an encouraging avenue for future energy conversion.