Photocurrent improvement from magnetron DC sputtered and thermally treated ruthenium-based catalyst decoration onto BiVO4 photoanodes

Abstract

Abstract Monoclinic BiVO4 (BVO) properties favor its use as the main absorber in photoanodes applied for photoelectrochemical water splitting. However, hindrances as the high rate of recombination of the electrons and holes photogenerated and as the poor charge carrier transport limit its direct, practical use. Doping, building a heterojunction with other semiconductors and decorating the surface with catalysts like cobalt phosphate and ruthenium oxide are among the many existing approaches to improve BVO performance. The deposition of catalyst or cocatalyst normally involve the use of potentially hazardous techniques as chemical vapor deposition (CVD). In this work, we present a simple route for enhancing photoelectrochemical results in BVO samples. The decoration with metallic ruthenium is performed via magnetron sputtering DC, a reliable, inexpensive and safe-to-use physical deposition technique, followed by a thermal treatment in air within a muffle furnace for 6\xa0h at 400\xa0°C. A gain of about 45% in the photocurrent at 1.23\xa0V vs reversible hydrogen electrode (RHE) and in the overall spectrum area in comparison with pristine BVO samples was registered by cyclic voltammetry measurements in a 0.5\xa0M phosphate buffer solution under full spectrum illumination from a 100\xa0W Xenon lamp. The morphological and chemical modifications that resulted in such photocurrent rise were characterized using Scanning Electron Microscopy (SEM), Rutherford Backscattering Spectrometry (RBS) and X-ray Photogenerated Spectroscopy (XPS).