Enhanced photoelectrochemical performance of WO3 film with HfO2 passivation layer

•HfO2 was loaded on the surface of WO3 nanoparticles as a passivation layer.•It was prepared by a simple solovethermal method instead of atomic layer deposition.•The passivation layer inhibits the electron-hole recombination on the surface of WO3.•Photoelectrochemical performance of WO3 has been improved after loading HfO2.

In this article, Hafnium oxide (HfO2) overlayer was reported to be loaded on the surface of WO3 nanoparticles by a simple solvothermal method for the first time. HfO2 powders were dissolved in the concentrated sulfuric acid as raw material. The physicochemical properties of WO3 nanoparticles with and without HfO2 passivation layer were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). For the film electrode prepared with doctor-blade method, scanning electron microscopy (SEM) and UV–vis absorbance spectroscopy (UV–vis) were used to determine the morphological and optical properties. Meantime, the photoelectrochemical properties of two samples were evaluated by means of liner sweep voltammogram, electrochemical impedance spectroscopy (EIS), intensity modulated photocurrent spectrum (IMPS) and incident photon to current conversion efficiency (IPCE). The WO3 film with HfO2 passivation layer showed better photoelectrochemical performance which could be ascribed to the inhibition of the recombination of electron-holes.