Tailoring *OCHO adsorption via Cu⁺-doping-induced Sn p-band center elevation in hierarchical SnS₂ microboxes for...

Electrochemical CO₂ reduction to formate is promising for carbon utilization, but simultaneously achieving high selectivity, fast kinetics, and durability remains challenging. Herein, we incorporate atomically dispersed Cu⁺ into hierarchical SnS₂ microboxes assembled from nanosheets (Cu-SnS₂) to modulate their electronic structure. Benefiting from an expanded active surface area and optimized charge transfer, Cu-SnS₂ exhibits a peak formate faradaic efficiency of 70.3% at -1.3 V vs. RHE, with a partial current density of -18.0 mA cm^-2 (1.8-fold higher than that of pristine SnS₂). It also exhibits robust catalytic and structural stability over 14 h of electrolysis. Density functional theory and projected density of states analyses reveal that Cu⁺ doping shifts the Sn p-band center upward, which strengthens the electronic coupling with the key *OCHO intermediate. This optimization dramatically lowers the thermodynamic barrier for the formate pathway from 1.07 eV (on pristine SnS₂) to 0.46 eV while suppressing competing pathways. This work highlights orbital-level band-structure engineering for designing highly selective post-transition metal chalcogenides for carbon conversion.