Fate and Reactivity of Peroxides Formed over BiVO₄ Anodes in Bicarbonate Electrolytes

For the electrochemical and photoelectrochemical synthesis of hydrogen peroxide, aqueous bicarbonate electrolytes have been reported with much higher efficiency compared to other alternatives. It was proposed that this is due to efficient oxidation of the bicarbonate to peroxymonocarbonate (PMC) with subsequently hydrolyzes to hydrogen peroxide. However, as we show herein, PMC forms stable concentrations and does not hydrolyze completely. Due to its much better oxidation kinetics this may influence the sensitivity of the employed peroxide quantification methods. Particularly commercial test strips are susceptible to this, giving rise to uncertainty about the validity of the high peroxide formation efficiency in bicarbonate electrolytes. On the other side, PMC’s superior oxidation kinetics may mean that the resulting solutions are even more potent oxidants than previously suspected.