Isopropanol-assisted synthesis of highly stable MAPbBr₃/p-g-C₃N₄ intergrowth composite photocatalysts and their interfacial charge carrier dynamics

Two phase photocatalysts can be intergrown with each other, resulting in superior photocatalytic properties. Herein, methylamine lead bromide (MAPbBr₃) wrapped/entrapped protonated graphitic carbon nitride (p-g-C₃N₄) intergrowth microcrystals were fabricated by mixing a pervoskite precursor with p-g-C₃N₄ colloidal sol. A highly stable isopropanol (IPA) solvent based photocatalytic system for dye degradation was demonstrated. The composite with an optimal p-g-C₃N₄ mass percentage of 3.3 wt% (denoted as MAPbBr₃/p-g-C₃N₄-1.0 mg) exhibited the highest photocatalytic degradation of malachite green (99.8%) within 10 min under visible light, which was 5.3-fold and 16-fold greater than that exhibited by its constituents separately. The strong chemical interaction and fundamental photophysical processes in MAPbBr₃/p-g-C₃N₄ were systematically evaluated by spectroscopic and electrochemical techniques, confirming the effective separation of photogenerated electron-hole pairs and faster interfacial charge transfer behavior. Furthermore, active superoxide radicals (O₂^-) played a vital role in the catalytic reaction, because of the significant photoinduced electron transfer rate (k_et) in the inverted type-I core/shell MAPbBr₃/p-g-C₃N₄ band configuration structure. In addition, MAPbBr₃/p-g-C₃N₄ has good cycling stability for 10 cycles and versatility for other cationic (RhB) and anionic (MO) dye pollutants, indicating the great potential for solar energy conversion into chemical energy.