[Display omitted] • Zn 0.5 Cd 0.5 S/ZnS(en) 0.5 composites with "type I" band alignment were constructed. • The photoluminescence emission evolution was studied for ZnS(en) 0.5 and the composite. • A H 2 generation rate of 108.76 mmol/g/h with a 2.15% STH efficiency was achieved. P-type semiconductor ZnS(en) 0.5 (en = NH 2 CH 2 CH 2 NH 2) hybridized with photocatalysts has been reported as an effective photocatalyst toward H 2 production. However, photocatalytic efficiency is still limited by the low charge transfer and high charge recombination. In this work, ZnS(en) 0.5 nanosheets with tunable loading densities of Zn 0.5 Cd 0.5 S nanoparticles were synthesized towards high photocatalytic H 2 evolution. Sharp interfaces of hexagonal Zn 0.5 Cd 0.5 S nanoparticles with underneath orthorhombic ZnS(en) 0.5 nanosheets, the strong electronic interaction with a large blue shift of S-Zn-N binding energy in the [S-Zn-(en) 0.5 ] group have been found. From the multiple photoluminescence emissions of ZnS(en) 0.5 and the Mott-Schottky curves of the composites, a type I band alignment with multiple midgaps is revealed for the Zn 0.5 Cd 0.5 S/ZnS(en) 0.5 interface, where ZnS(en) 0.5 provides an energy barrier for the photoexcited electrons of Zn 0.5 Cd 0.5 S and fast transfer channels for the holes from Zn 0.5 Cd 0.5 S to the redox via the midgaps. Together with the balance between light absorption and charge transfer property regulated by the loading density of Zn 0.5 Cd 0.5 S, an optimum H 2 generation rate of 108.76 mmol/g/h and a solar to hydrogen efficiency of 2.15% have been realized. Such a study provides an effective strategy for enhancing the photocatalytic property of the "type I" heterostructures with fast transfer channels for photoexcited holes. [ABSTRACT FROM AUTHOR]