Defect-Engineered Bi24O31Cl10 Nanosheets for Photocatalytic CO2 Reduction to CO.

The photocatalytic CO₂ conversion efficiency of semiconductor materials still suffers from the faint CO₂ surface adsorption capacity and sluggish reaction kinetics. Among the modification strategies, defect engineering is considered as a promising approach for ameliorating the catalytic performance of the bulk materials. Herein, an ionic liquid 1-dodecyl-3-methylimidazolium chloride-assisted alkali solvothermal method was employed for the synthesis of ultrathin Bi₂₄O₃₁Cl₁₀ nanosheets with abundant surface oxygen vacancies (Bi₂₄O₃₁Cl₁₀-OV). The existence of the surface oxygen vacancy provided sufficient catalytic sites and greatly strengthened the CO₂ adsorption and activation capacity. Furthermore, a newly created energy level in the forbidden band of the Bi₂₄O₃₁Cl₁₀-OV sample facilitated the photogenerated charge separation and transfer, boosting the reaction rate. Under the conditions of pure water and high-purity CO₂, the total CO yield of the Bi₂₄O₃₁Cl₁₀-OV sample was achieved up to 330 μmol/g after irradiation with a 300 W Xe lamp for 10 h, which was 3 and 7 times higher than the bulk counterpart and partial oxygen-repaired Bi₂₄O₃₁Cl₁₀-OV sample, respectively. Furthermore, isotope labeling experiments also verified that the actual carbon source in the product CO was from CO₂ molecules. These results reveal that surface oxygen vacancy engineering is an effective approach for developing high-performance bismuth-based solar fuel generation systems. [ABSTRACT FROM AUTHOR]