Synthesis and enhanced bias-free photoelectrochemical water-splitting activity of ferroelectric BaTiO3/Cu2O heterostructures under solar light irradiation

Abstract

Here, we first use a facile electrochemical deposition method to load Cu2O nanoparticles onto the BaTiO3 (BTO) surface to prepare BTO/Cu2O heterostructure photoanodes. Compared to the pure BTO photoanode, all BTO/Cu2O heterostructure photoanodes show outstanding visible light harvesting ability and greatly improved photoelectrochemical water splitting performance. By optimizing the loading amount of Cu2O nanoparticles, the photocurrent density achieved by BTO/Cu2O-100 photoanode is 0.26 mA/cm2 at 0 V versus Ag/AgCl, which is 2.6 times that of the bare BTO photoanode. In contrast with the photocurrent densities of the other reported BTO-based heterostructure photoanodes, the photocurrent density achieved by the present BTO/Cu2O-100 photoanode without bias voltage is much higher. Additionally, the maximum solar-to-hydrogen conversion efficiency of the BTO/Cu2O-100 heterostructure photoanode is 0.11% at 0.72 V versus reversible hydrogen electrode, approximately double that of BTO photoanode. The measurements of diffuse reflectance spectra, photoelectrochemical impedance and the room temperature photoluminescence spectra demonstrate that the improved photoelectrochemical performance contributes from the visible light absorption ability of Cu2O nanoparticles, efficient transport and separation of photogenerated electron-hole pairs, which are induced by the spontaneous polarization electric field of ferroelectric BTO, p-n junction and type-II band alignment of BTO/Cu2O heterostructure photoanode. A possible mechanism for the improved photoelectrochemical water splitting performance and charge transfer process is proposed.