Direct Z-Scheme 0D/2D Heterojunction of CsPbBr₃ Quantum Dots/Bi₂WO₆ Nanosheets for Efficient Photocatalytic CO₂ Reduction

Photocatalytic CO₂ reduction is an appealing approach to convert solar energy into high value-added chemicals. All-inorganic CsPbBr₃ quantum dots (QDs) have emerged as a promising photocatalyst for reducing CO₂. However, pristine CsPbBr₃ has a low catalytic performance, mainly due to severe charge recombination. Herein, a 0D/2D heterojunction of CsPbBr₃ QDs/Bi₂WO₆ nanosheet (CPB/BWO) photocatalysts is fabricated for photocatalytic CO₂ reduction. The CPB/BWO photocatalyst achieves excellent photocatalytic performance: the total yield of CH₄/CO is 503 μmol g^-1, nearly 9.5 times higher than the pristine CsPbBr₃. The CPB/BWO heterojunction also exhibits much-improved stability during photocatalytic reactions. On the basis of various characterization techniques, our investigations verified a direct Z-scheme charge migration mechanism between CsPbBr₃ QDs and Bi₂WO₆ nanosheets. The improved photocatalytic performance is originated from the high spatial separation of photoexcited charge carriers in CPB/BWO, which can also preserve strong individual redox abilities of two components. This work reports an efficient direct Z-scheme heterojunction photocatalytic system based on metal halide perovskites. The novel strategy we proposed may bring up new opportunities for the development of metal halide perovskite photocatalysts with greatly enhanced activities.