Coconut Shell Waste-Derived Porous Carbon-Supported Sn Catalysts for Efficient Electrochemical CO ₂ Reduction to Formic Acid and Deuterated Formic Acid

Industrial-level electrochemical CO₂ reduction reaction (CO₂RR) to form HCOO^- and DCOO^- requires robust Sn catalysts with high performance. In this study, the hydrothermal method was employed to load varying amounts of Sn precursors onto waste biomass-derived porous carbon to investigate the structure-activity relationship between Sn loading forms and HCOO^- selectivity. Through comprehensive <i>ex</i>/<i>in situ</i> characterizations, we discovered that with 5% Sn precursor addition, highly dispersed SnO₂ nanoparticles formed on the carbon support, enabling the catalyst to exhibit exceptional HCOO^- activity (Faradaic efficiency exceeding 90%) across a broad potential window. <i>In situ</i> attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and <i>in situ</i> Raman spectroscopy revealed that the highly dispersed SnO₂ nanoparticles enhance the stability of the *OCHO intermediate. Furthermore, when H₂O was replaced with D₂O, the generation of DCOO^- was observed, and good selectivity was maintained. This study provides a facile strategy for waste biomass conversion and the design of Sn-based catalysts for DCOO^- production.