Precise Structural Engineering of Bi-Cu@C Hollow Heterostructures via Component Modulation for Selective CO₂...

Bismuth-copper (Bi-Cu) bimetallic catalysts show significant promise for electrochemical CO₂ reduction but are often limited by structural simplicity and insufficient synergy between activity, selectivity, and stability. To address this, we developed an ingenious "selective etching-thermal diffusion" strategy for precisely fabricating heterostructured Bi-Cu nanoparticles embedded within a hollow carbon matrix (Bi-Cu@C HS). This approach enables controlled nanoscale structural evolution via component-regulated phase transformations, yielding tailored architectures from core-shell to hollow configurations. The optimized Bi-Cu@C HS catalyst demonstrates exceptional CO₂-to-formate conversion, achieving a high formate partial current density of 22.5 mA cm^-2 with 90% Faradaic efficiency (FE) at -1.16 V vs. RHE. This performance stems from synergistic Bi-Cu interfacial electronic interactions that accelerate electron transfer and stabilize the key *OCHO intermediate, combined with the hollow architecture maximizing active site accessibility and mass transport. Furthermore, the carbon matrix provides a nanoconfinement effect that suppresses active species leaching and mitigates catalyst poisoning, enabling stable operation for over 11 h with less than 7% activity decay. This work establishes a component-modulation-driven paradigm for precise nanoscale structural engineering and offers fundamental insights for designing advanced heterostructured catalysts for sustainable energy conversion.