Molybdenum sulfo-selenide nanocomposites with carbon nanotubes and reduced graphene oxide for photocatalytic hydrogen evolution reaction

Abstract

We report a facile method for the preparation of nanocomposites of molybdenum sulfo-selenide (MoS_xSe_1−x) with carbon nanotubes (CNTs) and reduced graphene oxide (RGO) via a solvothermal approach. The synthesized MoSSe@CNT and MoSSe@RGO nanocomposites are characterized by various microscopic and spectroscopic methods. We investigated the photocatalytic hydrogen evolution reaction (HER) performance of the MoSSe@CNT and MoSSe@RGO nanocomposites using eosin Y dye as a sensitizer, and triethanolamine as a sacrificial agent, under UV-vis light (Xenon lamp; 400 W) illumination. The highest photocatalytic HER activity of 5016 μmol h⁻¹ g⁻¹ is achieved with the MoSSe@RGO nanocomposite, which is ∼3 times higher than that of the bare MoS_xSe_1−x nanostructure (1754 μmol h⁻¹ g⁻¹). Meanwhile, the MoSSe@CNT nanocomposite shows a somewhat lower activity of 3622 μmol h⁻¹ g⁻¹. These results indicate that the growth of MoSSe over conducting CNT/RGO improves the HER activity of the MoSSe nanostructure, but 2D RGO offers more facile electron-transfer routes compared to 1D CNTs. The HER activity of the nanocomposites is comparable with some of the recently reported 2D transition-metal-based nanocomposites reported in the literature. Photoluminescence studies indicate that the facile charge-transfer interaction between MoSSe and RGO/SWCNT is responsible for the remarkable HER activity of the nanocomposites. Additionally, more exposed edge sites of vertically grown discrete MoSSe nanostructures in the case of the nanocomposites, as suggested by microscopic studies, plausibly also contribute to the improved photocatalytic HER activity.