Pulsed-Laser-Engineered Cu Single Atoms in δ-Bi₂O₃ Nanosheets for Efficient Formate-Producing Zn-CO₂ Batteries

Herein, we report a pulsed laser irradiation in liquid (PLIL) strategy that concurrently induces phase transformation, morphological reconstruction, and single-atom stabilization in bismuth oxide (Bi₂O₃) for efficient carbon-dioxide reduction reaction (CO₂RR). PLIL transforms α-Bi₂O₃ microrods to δ-Bi₂O₃ nanosheets, while simultaneous anchoring atomically dispersed Cu sites within the δ-Bi₂O₃ lattice. The CO₂RR activity of the PLIL-derived δ-Bi₂O₃ nanosheets substantially exceeds that of α-Bi₂O₃ microrods and is further improved in Cu single-atom-stabilized δ-Bi₂O₃ (Cu SA/δ-Bi₂O₃) nanosheets, which deliver a high Faradaic efficiency (93.55%) with a formate yield rate of 210 µM·h^-1·cm^-2 at -1.0 V (versus the reversible hydrogen electrode). The key surface intermediates, identified using situ Raman and ex situ Fourier-transform infrared spectroscopy, confirm the stabilization of *OCHO species during formate formation. Theoretical calculations reveal that Cu single-atom incorporation electronically modulates the δ-Bi₂O₃ matrix, optimizing the intermediate adsorption energies and lowering the reaction barrier of the CO₂-to-formate pathway. Furthermore, a Zn-CO₂ battery with a Cu SA/δ-Bi₂O₃ cathode delivers an output voltage of 1.74 V and converts CO₂ to formate while generating electricity for over 300 h of stable operation. The Zn-CO₂ battery successfully powers light-emitting diodes and a digital clock, underscoring its potential in real-world energy-carbon coupling applications.