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

Abstract

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.