Perovskite-Based MnSn(OH) ₆ Nanocubes Coupled with 2D Chalcogenide Cu ₃ SnS ₄ Nanosheets for Electrocatalytic Methanol Oxidation

Multinary chalcogenide of Cu3SnS4 nanosheets (NSs), perovskite-derived hydroxide MnSn(OH)6 nanocubes (NCs), and their heterostructures were prepared via the coprecipitation method. The structural, morphological, and electrochemical properties of the materials were investigated for all of the prepared nanoparticles. The prepared nanoparticles were tested as electrocatalysts for methanol oxidation. Among the electrocatalysts, Cu3SnS4 nanosheets (NSs) showed a superior performance (63 mA/cm2 at 100 mV/s) toward the methanol oxidation reaction driven by abundant Cu+ active sites, high electronic conductivity from Cu-d and S-p orbital hybridization, and relatively low charge transfer resistance (Rct = 6.84 Ω). However, it has limited stability (75% current retention after 1 h) and a relatively high Tafel slope (198.02 mV/dec). In contrast, in the case of the Cu3SnS4/MnSn(OH)6 heterostructure, a strong catalytic performance (46 mA/cm2) with outstanding stability (98% current retention) and low charge transfer resistance (Rct = 7.1 Ω) was observed. This is attributed to the incorporation of Mn with Cu+ that reduced site density (due to strong Mn–S bonds) and enhanced the durability by stabilizing the structure and mitigating CuO formation, as reflected by a low onset potential (0.32 V vs Ag/AgCl) and Tafel slope (131.8 mV/dec). This study suggests that Cu–Sn–Mn-based nanostructures can improve electrocatalytic performance and offer a superior candidate as an alternative to highly expensive Pt for electrochemical energy conversion.