Fabrication of BiVO4 submicron rods photoanodes through phase transition assisted by Mo doping

Abstract

The contradiction between the optical absorption depth and carrier diffusion length has emerged as a significant problem constraining the performance of BiVO₄ photoanodes. Fabricating a one-dimensional (1D) structure is considered a promising strategy to address the above problem. However, the synthesis of BiVO₄ photoanodes consisting of 1D monoclinic scheelite remains a great challenge. In this study, a 1D molybdenum (Mo) doped BiVO₄ photoanode (Mo:1D-BVO) consisting of monoclinic scheelite BiVO₄ submicron rods (SMRs) through a phase transition from a 1D tetragonal zircon BiVO₄ precursor was successfully prepared. It was found that Mo doping could lower the phase transition barrier from tetragonal zircon to monoclinic scheelite BiVO₄. Due to the Mo:1D-BVO photoanode's remarkable light absorption efficiency, efficient carrier separation, and superior conductivity, it yields a photocurrent density of 2.08 mA cm⁻² at 1.23 V versus reversible hydrogen electrode (RHE), which is 3.5 times higher than that of pristine BiVO₄. Upon the introduction of the co-catalyst, the photocurrent density of Co–Pi/Mo:1D-BVO attains 3.18 mA cm⁻² at 1.23 V vs. RHE, accompanied by a carrier separation efficiency of 91%. Our study introduces a novel approach for the production of remarkably efficient 1D monoclinic scheelite BiVO₄ photoanodes.