Abstract
The electrochemical production of hydrogen peroxide (H(2)O(2)) by 2-electron oxygen reduction reaction (ORR) is an attractive alternative to the present complex anthraquinone process. The objective of this paper is to provide a state-of-the-arts review of the most important aspects of this process. First, recent advances in H(2)O(2) production are reviewed and the advantages of H(2)O(2) electrogeneration via 2-electron ORR are highlighted. Second, the selectivity of the ORR pathway towards H(2)O(2) formation as well as the development process of H(2)O(2) production are presented. The cathode characteristics are the decisive factors of H(2)O(2) production. Thus the focus is shifted to the introduction of commonly used carbon cathodes and their modification methods, including the introduction of other active carbon materials, hetero-atoms doping (i.e., O, N, F, B, and P) and decoration with metal oxides. Cathode stability is evaluated due to its significance for long-term application. Effects of various operational parameters, such as electrode potential/current density, supporting electrolyte, electrolyte pH, temperature, dissolved oxygen, and current mode on H(2)O(2) production are then discussed. Additionally, the environmental application of electrogenerated H(2)O(2) on aqueous and gaseous contaminants removal, including dyes, pesticides, herbicides, phenolic compounds, drugs, VOCs, SO(2), NO, and Hg(0), are described. Finally, a brief conclusion about the recent progress achieved in H(2)O(2) electrogeneration via 2-electron ORR and an outlook on future research challenges are proposed.