Improved water oxidation via Fe doping of CuWO4 photoanodes: Influence of the Fe source and concentration*

Abstract

Iron (Fe) was successfully doped in CuWO4 photoanode films with a combined liquid-phase spin-coating method via the dopant sources of Fe(NO3)3, FeSO4 and FeCl3. The microstructure of the prepared films was characterized by x-ray diffraction, scanning electron microscopy, and atomic force microscopy. The light absorption and photoelectric conversion properties were evaluated by the UV-visible absorption spectra and monochromatic incident photon-to-electron conversion efficiency. The chemical composition and element combination of the samples were examined by x-ray photoelectron spectroscopy. A linear sweep voltammetric and stability test (I–t) were performed with an electrochemical workstation. The results show that the samples are uniform with a thickness of approximately 800 nm and that the photoelectrochemical performance of the doped films is heavily dependent on the Fe source and dopant concentration. Upon optimizing the doping conditions of Fe(NO3)3 and the optimal source, the photocurrent density in the Fe-doped CuWO4 photoanode film is improved by 78% from 0.267 mA/cm2 to 0.476 mA/cm2 at 1.23 V vs reversible hydrogen electrode. The underlying causes are discussed.