Preparation of a MWCNTs/ZnIn2S4 composite and its enhanced photocatalytic hydrogen production under visible-light irradiation

Abstract

Multiwalled carbon nanotubes (MWCNTs) and ZnIn₂S₄ composites were prepared by a facile hydrothermal method, which was used for hydrogen production under visible-light (λ ≥ 420 nm) irradiation. The obtained MWCNTs/ZnIn₂S₄ composites were characterized by X-ray diffraction (XRD), thermogravimetric and differential scanning calorimetry analyses (TG-DSC), field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance absorption spectra (DRS), Fourier transform IR spectroscopy (FTIR) and Photoluminescence spectra (PL). It was found that the MWCNTs were embedded into the interior of floriated ZnIn₂S₄ microspheres. The effects of the composite ratio in the MWCNTs/ZnIn₂S₄ on the photocatalytic activity for hydrogen production were investigated. The results show that the 3 wt% MWCNTs/ZnIn₂S₄ composite reaches its maximum photocatalytic hydrogen production efficiency with an apparent quantum efficiency as high as 23.3% under 420 nm light irradiation. The significantly enhanced photoactivity for the present composite originates from the synergetic effect of its component intrinsic properties. A possible mechanism of the MWCNTs/ZnIn₂S₄ composite as a photocatalyst for H₂ evolution was proposed.