Photoelectrochemical Hydrogen Peroxide Production via Simultaneous Reduction and Oxidation Processes

ABSTRACT Hydrogen peroxide (H 2 O 2 ) is an essential substance in chemistry and chemical industry, while being a clean fuel. Currently, research into green and sustainable processes for producing H 2 O 2 is progressing rapidly, with the aim of replacing the energy‐intensive anthraquinone process used in industrial production. Among them, the photoelectrochemical (PEC) method is one that has attracted much attention, because it allows for the solar‐driven production of H 2 O 2 from only water and oxygen. Furthermore, highly designed PEC cells enable the simultaneous production of H 2 O 2 at the anode and cathode (H 2 O 2 /H 2 O 2 ‐PEC cells). This review article focuses on the H 2 O 2 /H 2 O 2 ‐PEC cells having the potential to achieve a Faraday efficiency ( η ) exceeding 100% for H 2 O 2 , with an emphasis on the relationship between electrode materials properties and cell performances. The H 2 O 2 /H 2 O 2 ‐PEC cells can be classified into two types: one involving water oxidation reaction and oxygen reduction reaction (WOR/ORR), and a more recently developed type involving oxygen reduction reaction at both electrodes (ORR/ORR). Based on the fundamental principles of the H 2 O 2 /H 2 O 2 ‐PEC cells, we discussed the electrode material design, and then review some cutting‐edge research on the WOR/ORR‐ and ORR/ORR‐PEC cells. Finally, we summarize the conclusions, and outline challenges and perspectives in this hot topic.