Boosting CsPbBr₃-Driven Superior and Long-Term Photocatalytic CO₂ Reduction under Pure Water Medium: Synergy Effects of Multifunctional Melamine Foam and Graphitic Carbon Nitride (g-C₃N₄)

Achieving high-efficiency and long-term CO₂ photoreduction under an aqueous environment is still a challenge for CsPbBr₃-based catalysts due to the poor humidity resistance. Herein, multifunctional melamine foam (MF) and graphitic carbon nitride (g-C₃N₄) are selected to modify CsPbBr₃, successfully realizing efficient and long-term CO₂ reduction under pure H₂O medium. The 3D framework of MF can support CsPbBr₃, avoiding its degradation due to direct contact with the aqueous solution. In addition, the abundant porosity of MF can accelerate H₂O evaporation, achieving sufficient blending of CO₂ with H₂O vapor. These functions lead to the enormously enhanced conversion efficiencies of MF/CsPbBr₃ and MF/g-C₃N₄ compared to powdery catalysts. Photocatalytic activities of MF/CsPbBr₃-g-C₃N₄ are further improved due to the accelerated charge migration, and accordant sites of electron accumulation and CO₂ adsorption in composites. The best product yield of the composite is 975.57 μmol g⁻¹ h⁻¹, and the corresponding electron consumption rate reaches 2571.27 μmol g⁻¹ h⁻¹, surpassing almost all the already reported CsPbBr₃-based catalysts whether in H₂O or organic solvent media. Moreover, the strong surface hydrophobicity and excellent photothermal effect of MF/CsPbBr₃-g-C₃N₄ result in long-term and stable photocatalytic activity, with no obvious CO and CH₄ decrease after continuous reaction for 76 h.