Polyoxometalate Induced Bismuth Sulfide Sub-1 nm Nanowires as Efficient Photocathodes in Li-CO₂ Batteries

The 1D sub-1 nm nanowires (SNWs) usually possess a highly promising avenue in catalysis and energy storage fields owing to their high aspect ratios facilitating charge transport, and near 100% surface atomic exposure offering abundant active sites. However, current research is mainly focused on metal oxide SNWs, whereas the synthesis of sulfide SNWs has been rarely reported. Herein, a new kind of Bi₂S₃-phosphomolybdic acid (Bi₂S₃-PMA) SNWs induced by polyoxometalate clusters has been successfully prepared. Molecular dynamics simulation demonstrates that PMA and Bi₂S₃ co-assemble into stable 1D SNWs via non-covalent interactions. Benefiting from the unique sub-1 nm structure and the synergetic effects of Bi₂S₃ and PMA, the SNWs exhibit enhanced light absorption ability, well-matched energy band structure, and efficient separation/transfer capability of photo-generated carriers. As the cathode catalyst in light-assisted Li-CO₂ batteries (LCBs), the Bi₂S₃-PMA-based LCBs deliver a low overpotential of 0.22 V, superior cycling stability for 300 h at 0.01 mA cm^-2 and 150 h at 0.05 mA cm^-2. Meanwhile, the battery also realizes an exceptionally long-term lifetime of 4000 h under no light. Density functional theory calculations disclose that the presence of electron-rich PMA promotes the adsorption of LiCO₂ and Li₂CO₃ on SNWs, which further boosts battery efficiency.