Amorphous molybdenum sulfide as highly efficient electron-cocatalyst for enhanced photocatalytic H2 evolution

• Published in: Applied catalysis. B, Environmental Vol. 193; pp. 217 - 225
• Main Authors: Yu, Huogen, Xiao, Pian, Wang, Ping, Yu, Jiaguo
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-09-2016
• Subjects: Amorphous molybdenum sulfide; Electron cocatalyst; g-C3N4; Photocatalysis; Unsaturated S atoms; g-C3N4; Unsaturated S atoms; Electron cocatalyst; Amorphous molybdenum sulfide; Photocatalysis
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2016.04.028

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•Amorphous MoSx as an electron cocatalyst was anchored on the g-C3N4 surface.•Amorphous MoSx has more unsaturated active S atoms than the crystalline MoS2.•H2-evolution activity of g-C3N4 can be greatly improved by loading amorphous MoSx..•An electron-cocatalyst mechanism of amorphous MoSx was proposed.•Amorphous MoSx provide more unsaturated active S atoms as the active sites.
Exploiting novel and high-performance electron-cocatalysts without noble metallic element is of great significance for photocatalytic H2-evolution reaction. Molybdenum sulfide is one of the promising candidates of such electron-cocatalysts, but its present performance is intrinsically restrained by the scarce active sites of unsaturated S atoms. In this study, amorphous MoSx (a-MoSx) nanoparticles were directly anchored on the g-C3N4 surface by an adsorption-in situ transformation method with the aim of improving photocatalytic H2-evolution activity. It was found that compared with the crystalline molybdenum sulfide (c-MoS2), the a-MoSx cocatalyst clearly exhibited more unsaturated active S atoms due to its highly irregular arrangement structure. Photocatalytic experimental results suggested that the H2-evolution activity of g-C3N4 photocatalyst could be obviously improved by loading a-MoSx cocatalyst, which is obviously higher than that of unmodified g-C3N4 and c-MoS2/g-C3N4. More importantly, in addition to the g-C3N4, the amorphous MoSx could also work as the efficient electron cocatalyst to greatly enhance the photocatalytic performance of conventional H2-evolution materials such as TiO2 (a typical UV-light photocatalyst) and CdS (a typical Vis-light photocatalyst). On the basis of the present results, an electron-cocatalyst mechanism of amorphous MoSx was proposed to account for the improved photocatalytic H2-evolution activity, namely, the amorphous MoSx can provide more unsaturated active S atoms as the efficient active sites to rapidly capture protons from solution, and then promote the direct reduction of H+ to H2 by photogenerated electrons. Considering its low cost and high efficiency, the amorphous MoSx cocatalyst would have great potential for the development of high-performance photocatalytic materials used in various fields.