All-Inorganic Perovskite NiTiO₃/Cs₃Sb₂I₉ Heterostructure for Photocatalytic CO₂ Reduction to CH₄ with High...

Developing efficient and stable halide perovskite-based photocatalysts for highly selectivity reduction CO₂ to valuable fuels remains a significant challenge due to their intrinsic instability. Herein, a novel heterostructure featuring 2D Cs₃Sb₂I₉ nanosheets on a 3D flower-like mesoporous NiTiO₃ framework using a top-down stepwise membrane fabrication technique is constructed. The unique bilayer heterostructure formed on the 3D mesoporous framework endowed NiTiO₃/Cs₃Sb₂I₉ with sufficient and close interface contact, minimizing charge transport distance, and effectively promoting the charge transfer at the interface, thus improving the reaction efficiency of the catalyst surface. As revealed by characterization and calculation, the coupling of Cs₃Sb₂I₉ with NiTiO₃ facilitates the hydrogenation process during catalytic, directing reaction intermediates toward highly selective CH₄ production. Furthermore, the van der Waals forces inherent in the 3D/2D heterostructure with face-to-face contact provide superior stability, ensuring the efficient realization of photocatalytic CO₂ reduction to CH₄. Consequently, the optimized 3D/2D NiTiO₃/Cs₃Sb₂I₉ heterostructure demonstrates an impressive CH₄ yield of 43.4 µmol g^-1 h^-1 with a selectivity of up to 88.6%, surpassing most reported perovskite-based photocatalysts to date. This investigation contributes to overcoming the challenges of commercializing perovskite-based photocatalysts and paves the way for the development of sustainable and efficient CO₂ conversion technologies.