Self-regenerative Co2+/Co3+ mediation in Co-doped CdIn2S4 superstructures enables efficient sacrificial-agent-free H2O2 photogeneration

Photocatalytic H 2 O 2 production suffers from severe charge recombination and sacrificial agent dependency. Hydrangea-like Co-doped CdIn 2 S 4 superstructures (Co/CIS (HD)) synthesized via hydrothermal method exhibit hierarchical porous architecture that enhances light harvesting and reactant diffusion. Atomic Co doping introduces mixed-valence Co 2+ /Co 3+ species, reducing the work function from 6.287 to 5.896 eV and extending carrier lifetime. The dual-valent system establishes a self-regenerative redox cycle where Co 3+ mediates photogenerated electron transfer for O 2 activation while Co 2+ scavenges holes to suppress recombination and photocorrosion. Without sacrificial agents, the optimized 6.5-Co/CIS (HD) achieves an exceptional H 2 O 2 production rate of 1952 μmol g −1  h −1 under visible light, 6.33 times higher than pristine CdIn 2 S 4 . The catalyst maintains structural stability over five cycles due to dynamic Co 2+ /Co 3+ regeneration. This work provides a strategic design for efficient photocatalytic H 2 O 2 synthesis via synergistic morphological and electronic engineering.