Dual Z-scheme PCN/CdS/CdIn2S4 heterojunctions for effective production of H2, H2O2 and pollutant degradation

The PCN/CdS/CdIn 2 S 4 composites exhibit excellent photocatalytic performance for H 2 evolution, H 2 O 2 production and dye degradation. • Spontaneous interfacial band bending drives a dual Z-scheme pathway to preserve highly active photogenerated charge carriers. • The superoxide radicals (.•O 2 − ) is the primary species for both continuous H 2 O 2 generation and rapid pollutant decomposition. Addressing the escalating global energy and environmental crises demands efficient, sustainable, and robust technologies. In this study, a ternary composite PCN/CdS/CdIn 2 S 4 integrating phosphorus-doped carbon nitride (PCN), cadmium sulfide (CdS), and indium cadmium sulfide (CdIn 2 S 4 ) was rationally designed via a multi-step assembly process. The optimized heterojunction exhibits outstanding performance, achieving remarkable H 2 and H 2 O 2 production rates of 7614 and 6873 μmol∙g −1  h −1 , respectively. Additionally, it demonstrates ultra-fast degradation kinetics, mineralizing 99.4% of methyl orange within just 30 min. Mechanistically, spontaneous interfacial band bending drives a dual Z-scheme charge transfer pathway. This specific energy band alignment effectively preserves strongly reducing electrons and highly oxidizing holes while significantly suppressing charge carrier recombination. Furthermore, radical trapping confirms that superoxide radicals (∙O 2 − ) are the pivotal active species, driving a two-step single-electron reduction pathway (O 2 →∙O 2- →H 2 O 2 ) for continuous H 2 O 2 generation, and coupling synergistically with localized holes for rapid organic pollutant decomposition.