Abstract
Developing a high-performance photocatalyst is important for realizing efficient photocatalytic H2O2 generation. Herein, a novel step-scheme (S-scheme) heterojunction photocatalyst C3N4/PDA (CNP) comprised of ultrathin g-C3N4 (U-CN) and polydopamine (PDA) is constructed by in situ self-polymerization. The optimal photocatalyst presents an excellent H2O2 production rate of 3801.25 mu mol g(-1)h(-1) under light irradiation, which is about 2 and 11 times higher than that of pure U-CN and PDA, respectively, and exceeds most of the reported C3N4-based photocatalysts. The improvement of photocatalytic activity is ascribed to the synergistic effect of improved light absorption and promoted charge separation and transfer induced by the S-scheme heterojunction. In situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) reveals that the charge transfer route matches the 5-scheme mechanism. Rotating disk electrode (RDE) measurements and electron spin resonance (ES R) spectroscopy verify that H2O2 is produced by a two-step one-electron process. This work highlights a promising method to construct high-performance S-scheme heterojunction photocatalysts through the hybridization of PDA and C3N4.