In situ construction of Cs₃Bi₂I₉/WO₃ 0D/1D Z-scheme heterojunction photocatalyst for photochemical CO₂ reduction under visible light

The photocatalytic efficiency of lead-free Bi-based halide perovskites, such as Cs₃Bi₂X₉ (X = Br, I) for CO₂ reduction is often hindered by self-aggregation and insufficient oxidation ability. In this work, a visible-light-driven (λ > 420 nm) Z-scheme heterojunction photocatalyst composed of 0D Cs₃Bi₂I₉ nanoparticles on 1D WO₃ nanorods for photocatalytic CO₂ reduction and water oxidation is synthesized using an in situ growing approach. The resulting 0D/1D Cs₃Bi₂I₉/WO₃ Z-scheme heterojunction photocatalyst exhibits a visible-light-driven photocatalytic CO₂ reduction performance for selective CO production, achieving a selectivity of 98.7% and a high rate of 16.5 (µmol/(g·h), approximately three times that of pristine Cs₃Bi₂I₉. Furthermore, it demonstrates decent stability in the gas-solid photocatalytic CO₂ reduction system. The improved performance of Cs₃Bi₂I₉/WO₃ is attributed to the formation of the 0D/1D Z-scheme heterojunction, which facilitates charge transfer, reduces charge recombination, and maintains the active sites of both 0D Cs₃Bi₂I₉ for CO₂ reduction and 1D WO₃ for water oxidation. This work provides valuable insights into the potential of morphological engineering and the design of simultaneous Z-scheme heterojunction for lead-free halide perovskites.