<p>Carbon dioxide (CO₂) can be electrochemically converted to formate/formic but finding an easily accessible, selective and stable catalyst is an ongoing challenge. Here, we show unique surface-enhanced bimetallic In-Sn alloy, In₇₀Sn₃₀, and In₃₀Sn₇₀ catalysts, prepared by controlled electrochemical nanoscale surface-texturing and chemical surface-etching for efficient conversion of CO₂ to formic acid. Electrochemical conversion of carbon dioxide to formate is a high value process acquiring specific enhanced catalytic sites for high Faradic efficiency and greater product selectivity. Electrochemical and chemical surface-etched In₇₀Sn₃₀, catalysts show outstanding performance for CO₂ to formic acid conversion with a high Faradic efficiency of ~ 96% and 88% respectively, as compared to simple In and Sn based single metal catalysts and unetched In-Sn alloy. Furthermore, electrochemically surface-etched In₇₀Sn₃₀ catalyst remained stable during constant potential electrolysis attained formate Faradic efficiency 93% with current density of 9.8 mAcm^− 2 at -1.15&#xa0;V vs. RHE for 6&#xa0;h. catalytic testing. This work provides an insight about the both controlled-electrochemical and chemical surface- etched In₇₀Sn₃₀ alloys, induces distinct changes in phase crystallinity with enhanced formate selectivity. DFT simulations, revealed that variations in the electron and atomic arrangement of the catalyst’s surface affect the interaction energy and formation free energy of different chemical intermediates, which in turn can affect the end-products’ selectivity. The findings reveal that etching methods significantly enhance formate selectivity and activity, providing mechanistic insight beyond previously reported composition- or alloy-focused studies.</p>