Fate and Reactivity of Peroxides Formed over BiVO ₄ Anodes in Bicarbonate Electrolytes

Abstract

sı Supporting Information H ydrogen peroxide is one of the most important chemical compounds, employed for many different processes, 1 including chemical synthesis, 2 bleaching, 3 disinfection, 4 and water treatment. 5The high content of active oxygen and the fact that it forms only water as a byproduct make it a very environmentally friendly oxidant, giving it a rise in prominence as green chemistry grows in significance.However, hydrogen peroxide is currently produced almost exclusively using the anthraquinone process, 6 which is very energy-intensive, leading to high CO 2 emissions from the steam reforming used to produce the required hydrogen gas.The process is also only efficient in centralized large plants, requiring complex logistics to bring it to the usually delocalized consumers.Due to the instability of hydrogen peroxide, stabilizers must be added for transport and storage. 7n order to solve these problems, new synthesis routes for the production of hydrogen peroxide directly at the place of use are highly sought-after.Electrochemical 8 and photocatalytic 9 processes are particularly suitable for this purpose.The electrochemical method offers a safe, environmentally friendly, and technically feasible variant of H 2 O 2 production.Hydrogen peroxide can be produced via two different electrochemical reactions.One possibility is the well-known reduction of molecular oxygen at the cathode in a two-electron process (eq 1).On the other hand, the oxidation of water may also yield hydrogen peroxide at the anode (eq 2).The challenge in this reaction is to prevent the subsequent overoxidation of the peroxide to oxygen (eq 3).Also, the direct four-electron oxidation to oxygen (eq 4) needs to be prevented.

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