Graphene decorated MoS2 for eosin Y-sensitized hydrogen evolution from water under visible light

Abstract

Some two-dimensional nanomaterials, such as graphene and molybdenum disulfide, are presently being intensively investigated due to their excellent and unique performances. In the field of photocatalysis, MoS₂ is considered as a promising alternative to noble metal Pt for the hydrogen evolution reaction (HER). However, its poor electrical conductivity restricts its catalytic activity in the HER. In this work, MoS₂ was modified with graphene (G) by a simple hydrothermal method. The prepared G/MoS₂ composite was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results show that graphene modification does not influence the crystal phase of MoS₂, but makes the latter more dispersed. The HER performance of G/MoS₂ was evaluated using eosin Y (EY) as a photosensitizer, and triethanolamine (TEOA) as a sacrificial electron donor under visible-light irradiation (λ > 420 nm, 250 W high pressure Hg lamp as light source). The EY sensitized G/MoS₂ composite displays enhanced hydrogen evolution in terms of not only activity but also stability. The average HER activity (9.1 μmol h⁻¹) is three times that of EY sensitized pure MoS₂ over 10 h. It is believed that the incorporation of graphene enhances the charge transfer ability and retards the self-degradation path of EY˙⁻, ultimately improving the HER.