Noble metal-free cobalt oxide (CoOx) nanoparticles loaded on titanium dioxide/cadmium sulfide composite for enhanced photocatalytic hydrogen production from water

In this present paper, cobalt oxide (CoOx) is studied as an effective cocatalyst in a photocatalytic hydrogen production system. CoOx-loaded titanium dioxide/cadmium sulfide (TiO2/CdS) semiconductor composites were prepared by a simple solvothermal method and characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviole-visible diffuse reflectance spectroscopy (UV-Vis DRS), and X-ray photoelectron spectroscopy (XPS). Photocatalytic hydrogen production was studied using the as-synthesized photocatalysts in aqueous solution containing sodium sulfide (Na2S)/sodium sulfite (Na2SO3) as hole scavengers under visible light irradiation (lambda > 400 nm). The optimal cobalt content in CoOx-loaded TiO2/CdS composite is determined to be 2.1 wt% and the corresponding rate of hydrogen evolution is 660 mu mol g(-1) h(-1), which is about 7 times higher than TiO2/CdS and CdS photocatalysts under the same condition. Visible light-driven photocurrents of the semiconductor composites were further measured on a photoelectrochemical electrode, revealing that the photocorrosion of CdS can be prevented due to the presence of TiO2-CoOx. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.