MOF-derived Bi@NC electrocatalysts with heteroatomic engineering for high-efficiency CO2-to-formate conversion

Abstract

Electrochemical CO₂ reduction offers a sustainable pathway to convert CO₂ into value-added chemicals and fuels, addressing critical challenges of energy sustainability and environmental remediation associated with greenhouse gas emissions. However, developing efficient and durable electrocatalysts for selective formic acid (HCOOH) generation remains a critical challenge. Herein, we report a cost-effective nitrogen-doped carbon-supported bismuth nanoparticle (Bi@NC) catalyst derived from controlled pyrolysis of a bismuth-based metal–organic framework (MOF) with tunable dicyandiamide incorporation. The optimized Bi@NC achieves exceptional CO₂-to-HCOOH conversion with 96% faradaic efficiency at −1.1 V in a conventional H-cell configuration. Furthermore, during a 12-hour continuous electrolysis in a flow cell, Bi@NC maintains a stable current density of −220 mA cm⁻² at −1.7 V vs. RHE while retaining a faradaic efficiency for HCOOH of above 90%, highlighting its robustness under demanding conditions. Combined experimental and computational analyses reveal that the introduction of heteroatomic N into the carbon matrix can not only facilitate the dispersion of Bi nanoparticles and enhance the adsorption/activation of CO₂ through charge redistribution at the Bi–N–C interfaces, but also selectively stabilize *COOH intermediates via electronic structure modulation, promoting formate generation in electrochemical CO₂ reduction. This work establishes a rational design strategy for MOF-derived electrocatalysts, offering new insights into heteroatomic engineering for efficient CO₂-to-HCOOH conversion systems.