A Lead-Free 0D/2D Cs₃Bi₂Br₉/Bi₂WO₆ S-Scheme Heterojunction for Efficient Photoreduction of CO₂

Photocatalytic reduction of CO₂ into valuable hydrocarbon fuels is one of the green ways to solve the energy problem and achieve carbon neutrality. Exploring photocatalyst with low toxicity and high-efficiency is the key to realize it. Here we report a lead-free halide perovskite-based 0D/2D Cs₃Bi₂Br₉/Bi₂WO₆ (CBB/BWO) S-scheme heterojunction for CO₂ photoreduction, prepared by a facile electrostatic self-assembly approach. The CBB/BWO shows superior photoreduction of CO₂ under visible light with CO generation rate of 220.1 μmol·g^-1·h^-1, which is ∼115.8 and ∼18.5 times higher than that of Cs₃Bi₂Br₉ perovskite quantum dots (CBB PQDS) and Bi₂WO₆ nanosheets (BWO NS), respectively. The improved photocatalytic activity can be attributed to the tight 0D/2D structure and S-scheme charge transfer pathway between the Cs₃Bi₂Br₉ PQDS and atomic layers of the Bi₂WO₆ NS, which shortens transmission distance of photogenerated carriers and boosts efficient separation and transfer of the carriers. This work provides insight in manufacturing potential lead-free perovskite-based photocatalysts for achieving carbon neutrality.