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

•Cobalt oxide (CoOx) as cocatalyst on TiO2/CdS for photocatalytic H2 production.•Improved visible light-driven H2 production from water at room temperature.•Cobalt oxide is earth-abundant materials for catalytic reactions.•CoOx-loaded TiO2/CdS composite shows good photocatalytic activity and stability.

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), ultraviolet–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 (λ > 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 μmol 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.

Graphical abstractCobalt oxide (CoOx) is studied as an effective cocatalyst for photocatalytic hydrogen production on TiO2/CdS semiconductor heterojunction, which exhibits the rate of hydrogen evolution as high as 660 μmol g−1 h−1.Figure optionsDownload full-size imageDownload as PowerPoint slide