Highly Efficient Photocatalytic Hydrogen Production Performance for 2D/0D g-C₃N₄/Zn_0.5Cd_0.5S with g-C₃N₄as a Transport Medium for Photogenerated Charge Carriers

Two-dimensional g-C3N4 nanosheets are synthesized by high-temperature calcination. The prepared g-C3N4 is used further to synthesize a 2D/0D composite series based on g-C3N4/Zn0.5Cd0.5S heterojunction composite with varied amounts of g-C3N4. The structure, microscopic morphology, photoelectric and photocatalytic performance, and the mechanism for enhancement of photocatalytic performance of the samples are studied through various characterization methods. Microstructural studies revealed that 0D Zn0.5Cd0.5S nanoparticles (ca. 3 ∼ 5 nm) were uniformly dispersed over the surface of the g-C3N4 and thus the formation of a heterostructure. The photo-electrochemical test shows that an appropriate amount of g-C3N4 modification (10%-C3N4/Zn0.5Cd0.5S) can effectively improve photogenerated carriers separation and transfer efficiency. Besides, the hydrogen production performance of the g-C3N4/Zn0.5Cd0.5S samples first increased and then decreased with the amount of g-C3N4. The photocatalytic activity of the 10%-C3N4/Zn0.5Cd0.5S showed the highest hydrogen production of 3.53 mmlog-1·h-1, which is 2.8 times than that of pure Zn0.5Cd0.5S (1.26 mmol·g-1·h-1). The enhanced photocatalytic performance is attributed to the introduced g-C3N4 that can supply more activity sites and lead to the formation of the heterojunction across the interface, which effectively improves the separation and migration of photogenerated charges. Designing this kind of sustainable, low cost, and efficient photocatalytic hydrogen production method that avoids the application of precious metals will provide a feasible solution to meet the increasing global energy demand and a sustainable future.