Alteration of onset potentials of Rh-doped SrTiO3 electrodes for photoelectrochemical water splitting

Rh-doped SrTiO3 (Rh-STO) is a visible-light-responsive oxide semiconductor photocatalyst with applications to water splitting. In this work, the onset potentials of the Rh-STO electrodes were shifted in a wide range from 0 to 1.2 V vs. RHE via changing the amount of Rh dopants, or adjusting the ratio of Ti3+/Rh4+,3+ cations through a vacuum-heating treatment. Namely, the photocathodic and photoanodic behavior of this material was successfully altered. The Rh4+,3+ cations that composing the acceptor energy levels of Rh-STO were characterized with UV–Vis diffuse reflectance and X-ray photoelectron spectroscopies. Visible-light-driven low-biased photoelectrochemical water splitting was achieved by connecting the as-prepared Rh-STO photoanode and photocathode in series. This work provides a new strategy of accomplishing overall water splitting using only one kind of semiconductor photocatalyst.