Highly dispersed NiS2 quantum dots as a promising cocatalyst bridged by acetylene black significantly improved the photocatalytic H2 evolution performance of g-C3N4 nanosheets

Abstract

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.