Conversion of Organically Directed Selenidostannate into Porous SnO2 Exhibiting Effective Electrochemical Reduction of CO2 to C1 Products

Development of porous catalysts for electrochemical reduction of CO2 relies on methodological innovation in regard to both rational structure design and feasible preparation. Organically directed selenidometalates emerge as a type of promising crystalline precursors for their homogeneously distributed templates that can undergo precise thermolysis and volatilization. Herein, we report the facile thermally driven conversion of choline-templated selenidostannate, [(CH3)3N(CH2)2OH]2[Sn3Se7]·H2O (Ch-Sn3Se7), into a series of mesoporous SnO2 (P-SnO2) materials as high-performance electrocatalysts for CO2 reduction. Variations of particle morphology/size and surface area with calcination time were systematically investigated and correlated to the electrocatalytic activity and product selectivity. The optimal electrode loaded with P-SnO2-0 min exhibits a high faradic efficiency (up to 94.5%), a large partial current density (∼11.5 mA cm–2), and excellent long-term stability (100 h) for transforming CO2 into useful C1 products (HCOOH + CO) at −1.06 V vs reversible hydrogen electrode (RHE), comparable to the top-level Sn-based catalysts. A detailed investigation into the long-term electrolysis revealed a gradual fragmentation of the pristine SnO2 nanoparticles along with partial SnO2–SnO–Sn self-reduction, which contributes to increased active sites that account for the highly selective and stable electrolysis process. This work provides a facile and low-cost templating method for the preparation of porous materials and gives some deeper insights into the course of the catalytic reaction that are of considerable industrial significance.