Furan-Based CS@CdS Heterojunction Achieves Fast Charge Separation to Boost Photocatalytic Generation of H2O2 in Pure Water

The efficient photocatalytic generation of hydrogen peroxide (H2O2) from pure water remains a formidable challenge, primarily due to the rapid recombination of photogenerated electron–hole pairs and insufficient redox potentials inherent in single-component photocatalysts. To address these issues, we designed and synthesized a heterojunction material comprising cadmium sulfide nanoparticles loaded on carbon spheres (CS@CdS). Under conditions utilizing pure water and ambient air, the CS@CdS composite achieves an H2O2 production rate of 1305 μmol·g−1·h−1, which is 3.1 and 3.6 times higher than that of pure CdS and CS, respectively, without the need for any sacrificial agents or external oxygen supply. Systematic characterization reveals that CS and CdS form a tightly coupled electronic interface, which significantly accelerates charge carrier separation and effectively prolongs the lifetime of photogenerated carriers, thereby boosting photocatalytic performance. Furthermore, the CS component extends the visible-light absorption range of the composite and functions as an electron acceptor to suppress charge recombination, collectively endowing CS@CdS with enhanced photocatalytic activity. Mechanistic studies indicate that H2O2 production over CS@CdS proceeds predominantly via a two-step single-electron oxygen reduction reaction (ORR) pathway. This work offers a viable strategy for constructing CS-based heterojunction photocatalysts for efficient H2O2 synthesis.