H2O2 Electrogeneration from O2 Electroreduction by N-Doped Carbon Materials: A Mini-Review on Preparation Methods, Selectivity of N Sites, and Prospects

Hydrogen peroxide (H2O2) is one of the 100 most paramount chemicals in the world, which has been widely used in industrial synthesis, pulp and bleaching, semiconductor cleaning, medical sterilizing, environmental treatments, and energy storage. Among various H2O2 production methods, anthraquinone process has intrinsic drawbacks such as energy-intensive and environmental pollution while 2-electron oxygen reduction reaction (ORR) provides an economic, efficient, and nonhazardous alternative process to realize the in situ production of H2O2 instead. Recently, heteroatom-doped carbon electrocatalysts, especially the nitrogen-doped ones, receive special attention due to the tunability on selectivity, activity, and stability towards ORR. In this review, the preparation methods on N-doped carbon-based electrocatalysts with different nitrogen forms are systematically classified, the mechanism of specific nitrogen morphology acting on two-electron ORR is discussed, especially the selectivity, and the factors (pH, nitrogen content, active surface site density, physical properties of carbon substrates) affecting the ORR selectivity of N-doped electrocatalysts are analyzed. Moreover, the preparation of H2O2 with N-doped carbon materials in different experimental systems is also summarized. Finally, the development direction of H2O2 synthesis by 2-electron ORR is prospected, and the suggestions from the aspects of production technology, testing method, and theoretical research are put forward.

Automated summary

This review systematically classifies the preparation methods of N-doped carbon-based electrocatalysts with different nitrogen forms, discusses the mechanism of specific nitrogen morphology on two-electron ORR, especially the selectivity, and analyzes the factors affecting the ORR selectivity of N-doped electrocatalysts. The potential applications of N-doped electrocatalysts in oxygen reduction reaction are highlighted.