Boosting the photoelectrochemical performance of BiVO 4 by borate buffer activation: the role of trace iron impurities.

BiVO ₄ is an attractive photoanode material for water oxidation, but requires surface treatment to improve the energy efficiency and stability. Herein, we investigate the role of borate buffer in activating the BiVO ₄ photoanode. We found that trace iron impurities in the borate buffer play a critical role in activating the photoanode. By optimizing the activation conditions, the photocurrent density attains 4.5 mA cm ^-2 at 1.23 V _RHE without any cocatalysts, alongside a high ABPE value of 1.5% at 0.7 V _RHE . Our study discloses the role of iron in the activation effect of borate buffer on the BiVO ₄ photoanode, which has implications for other catalytic systems.