Tuning photocatalytic performance of Cs3Bi2Br9 perovskite by g-C3N4 for C(sp3)—H bond activation

All-inorganic halide perovskite (IHP) has been deemed promising in photocatalysis due to tunable bandgap and long lifetime of charge carriers. However, unsatisfactory photocatalytic activity and low stability prevent its practical applications. Rational construction of heterojunctions has been proved to be an efficient way to circumvent these obstacles. Herein, g-C3N4 nanosheet was employed to construct a 2D/2D (2D: two-dimensional) heterostructure with Cs3Bi2Br9 through an electrostatic self-assembly process. Owing to the efficient transfer of photogenerated charge carriers, the activity of Cs3Bi2Br9 was boosted with enhanced generation of carbon centered radicals. The optimized 10% Cs3Bi2Br9/g-C3N4 composite displays the highest benzaldehyde formation rate of 4.53 mmol·h−1g−1 under visible light, which is 41.8 and 2.3 times that of individual g-C3N4 and Cs3Bi2Br9, respectively. The stability of Cs3Bi2Br9 nanosheets and its selectivity for benzaldehyde (from 65% of Cs3Bi2Br9 to 90% of the composite) was enhanced by reducing its surface energy and tuning the reaction pathway, respectively.