Effect of Mn2+ incorporation on the photoelectrochemical properties of BiVO4

Abstract

BiVO₄ is a promising photoanode material for photoelectrochemical water splitting applications due to its narrow band gap, i.e., ∼2.4 eV, suitable band-edge positions, non-toxicity, and high stability. Here, we report the synthesis of Mn²⁺-doped BiVO₄ with varying concentrations of Mn²⁺ (0.2–1.0%) to improve the charge-transport properties of the catalyst. The addition of Mn enables forbidden d–d transitions, which are utilized to slow down the charge-carrier recombination and increase the efficiency. The highest efficiency was achieved in the case of the 1.0% Mn²⁺–BiVO₄ photoanode, which exhibits a photocurrent density of 1.163 mA cm⁻² at 1.23 V and 1.56 mA cm⁻² at 1.4 V vs. RHE. The enhanced photoelectrochemical performance of Mn²⁺–BiVO₄ implies a higher charge-carrier separation and an improved electrical conductivity. This suggests that Mn²⁺-doped BiVO₄ may be used as a promising photoanode in future energy-conversion devices.