S bridged mediated S-scheme heterojunction in CdS/S-doped g-C3N4 for ultrafast electron transfer and high-efficiency photocatalytic H2O2 production

Photocatalytic H 2 O 2 synthesis offers a sustainable route to address energy and environmental challenges, yet conventional catalysts suffer from rapid carrier recombination and sluggish reaction kinetics. Here, we report a CdS/S-doped g-C 3 N 4 (CUT) heterostructure with an interfacial ‘S bridge’ mediated S-scheme charge transfer mechanism. The S-doped g-C 3 N 4 (UT) broadens visible-light absorption, while the -SO x forms a unique S bridged interface, enabling directional electron transfer from UT to CdS. This creates an electron-rich surface that stabilizes critical ·O 2 − intermediates for the selective 2e − oxygen reduction pathway. Synergistically, the S-scheme heterojunction retains strong redox potentials by recombining low-energy charges, enhancing charge separation and O 2 activation. Remarkably, the optimized CUT-60 achieves a H 2 O 2 production rate of 23.55 μmol h −1 under visible light—14.36 times and 2.74 times higher than pristine g-C 3 N 4 and UT, respectively, and the AQY of CUT-60 is 7.1 %, exceeding most CN-based photocatalysts. Stability tests and mechanistic studies confirm robust recyclability and elucidate the dual role of the S bridge in accelerating electron transport and suppressing carrier recombination. This work offers a universal paradigm for designing high-performance photocatalysts with tailored charge-transfer highways.