Carbon-coated bismuth catalyst for efficient and stable CO₂ electroreduction to formate

Bismuth (Bi)-based catalysts are extensively employed for the electrocatalytic CO₂ reduction (ECR) for formate production. However, their practical application is constrained by inadequate catalytic activity and limited operational stability. In this study, two types of catalysts (carbon-supported Bi particles (Bi/C) and carbon-coated Bi particles (Bi@C)) were prepared via ligand modulation of Bi-based metal-organic frameworks. The role of interaction mode between Bi particles and carbon on the activity and stability was investigated. In contrast to the Bi/C catalyst, the coated carbon layer in the Bi@C catalyst improves charge transfer and optimizes the reaction kinetics, resulting in a higher current density and Faradaic efficiency of formate (FE_formate). Furthermore, the coated structure effectively stabilizes Bi active sites, thereby substantially improving activity in acidic electrolyte and long-term stability. The Bi@C catalyst exhibits remarkable stability in both alkaline (pH = 14.00) and acidic (pH = 1.00) electrolytes at 120 mA cm^-2, while preserving FE_formate/FE_HCOOH above 90%, showing promising potential for practical and industrial CO₂ electroreduction. This work can provide novel insights into the design of efficient and long-term stability Bi-based ECR catalysts.