A perovskite solar cell-TiO2@BiVO4 photoelectrochemical system for direct solar water splitting

Abstract

Converting solar energy into hydrogen via photoelectrochemical water splitting has attracted significant attention during the past decades. Herein, we design a novel core/shell TiO₂@BiVO₄ photoanode in combination with a CH₃NH₃PbI₃-based perovskite solar cell for unassisted solar water splitting. Compared to pristine TiO₂ NRs, the resulting TiO₂@BiVO₄ film exhibits a 3.25-fold enhanced photocurrent density (∼1.3 mA cm⁻²) under irradiation (xenon lamp coupled with an AM 1.5 G filter, 100 mW cm⁻²). This significant enhancement is attributed to the excellent light absorption properties of BiVO₄ and a fast electron transfer process in the single crystalline TiO₂ NRs. Especially, the type-II band alignment between the BiVO₄ and rutile TiO₂ NRs provides a large driving force for electron injection from the BiVO₄ to the TiO₂. The perovskite solar cell-TiO₂@BiVO₄ photoelectrochemical tandem device exhibits an overall solar-to-hydrogen efficiency of 1.24%, comparable to other TiO₂-based PV/PEC systems.