Highly Dispersed NiS2 Quantum Dots As a Promising Cocatalyst Bridged by Acetylene Black Significantly Improved the Photocatalytic H2 Evolution Performance of G-C3n4 Nanosheets.

In this work, ternary nanocomposite (CNs-AB/NiS2) as a novel efficient H2 evolution photocatalyst without the use of noble metals was successfully synthesized by depositing acetylene black (AB) and ultra-fine NiS2 nanoparticles on the surface of CNs (g-C3N4) through ultrasonic dispersion and chemical vapor deposition methods, respectively. It was revealed that the loaded AB and NiS2 nanoparticles have significantly improved the photocatalytic H2 evolution efficiency of the CNs by improving the photogenerated electron-hole pair separation, visible light absorption and hydrogen evolution kinetics. Besides acting as a cocatalyst, AB served as a conductive electron bridge between CNs and NiS2, which accelerated the effective transfer of electrons from CNs to NiS2 and improved the H2 evolution kinetics of the NiS2 cocatalyst. The H2 evolution experiments revealed that the ternary photocatalyst CNs-AB/NiS210 displayed a H2 evolution rate of up to 2434.85 μmoL g-1 h-1, which was a 1.41 times enhancement compared to that of the binary composite CNs-NiS210 and was 12.43 times higher than that of the pure CNs. Moreover, the ternary photocatalyst CNs-AB/NiS210 not only exhibited excellent photocatalytic activity and stability in the tests, but provided a novel idea for the development of high-efficiency catalysts free of noble metals as well.