Efficient visible-light-driven photocatalytic hydrogen production over a direct Z-scheme system of TaON/Cd0.5Zn0.5S with a NiS cocatalyst.

In this work, a series of samples of Cd0.5Zn0.5S (ZCS) nanoparticles decorated with porous TaON were successfully prepared as a direct Z-scheme system. The photocatalytic evolution of H2 with a high efficiency was explored using NiS decorated with TaON sensitized ZCS nanocomposites (NiS-TaON/ZCS) and Na2SO3/Na2S as sacrificial reagents. The results showed that 0.5 wt% NiS deposited on the surface of 4 wt% TaON-ZCS nanocomposites could reach the highest photocatalytic H2 evolution rate of 34.8 mmol h-1 g-1 with a maximum quantum yield of about 25.5% under 420 nm monochromatic light. The activity of the TaON-ZCS photocatalyst for photocatalytic H2 evolution is higher than that of either pure ZCS or TaON. This high photocatalytic performance is ascribed firstly to the hierarchical structure of the coupled semiconductor system and secondly to the efficient transfer and separation of photogenerated charge carriers with NiS as a cocatalyst, which could serve as an electron collector.