La³⁺-Substituted BaSnO₃ Perovskite as a Robust Electrocatalyst for Selective CO₂ Reduction to Formate

Rational design of high-performance catalysts for CO₂ electroreduction is crucial for achieving carbon neutrality, yet effective modification strategies remain scarce. In this study, we present the microwave heating approach to incorporate La³⁺ ions into Sn-based perovskite oxides, significantly enhancing their electrocatalytic performance for the reduction of CO₂ to formate. Through comprehensive characterization techniques, including X-ray photoelectron spectroscopy, synchrotron radiation X-ray absorption spectroscopy, electrochemical measurements (Tafel analysis and impedance spectroscopy), and density functional theory calculations, we demonstrate that La³⁺ substitution effectively modulates the Sn-O bond distance in BaSnO₃. This structural modification induces local charge density enrichment, facilitates CO₂ adsorption, and enhances electron transfer kinetics, resulting in a substantial improvement in the formate Faradaic efficiency. In situ Raman spectroscopic analysis and postreaction XPS characterization confirmed the structural integrity of the perovskite framework and the preservation of Sn valence states under negative potentials. This work provides fundamental insights into the CO₂ reduction reaction mechanism on perovskite electrocatalysts and establishes a framework for the design of advanced tin-based electrocatalysts.