Ultra‐Rapid Electrocatalytic H2O2 Fabrication over Mono‐Species and High‐Density Polypyrrolic‐N Sites

Abstract

AbstractElectrocatalytic hydrogen peroxide (H2O2) production via two‐electron oxygen reduction reaction (2e−‐ORR) features energy‐saving and eco‐friendly characteristics, making it a promising alternative to the anthraquinone oxidation process. However, the common existence of numerous 2e−‐ORR‐inactive sites/species on electrocatalysts tends to catalyze side reactions, especially under low potentials, which compromises energy efficiency and limits H2O2 yield. Addressing this, a high surface density of mono‐species pyrrolic nitrogen configurations is formed over a polypyrrole@carbon nanotube composite. Thermodynamic and kinetic calculation and experimental investigation collaboratively confirm that these densely distributed and highly selective active sites effectively promote high‐rate 2e−‐ORR electrocatalysis and inhibit side reactions over a wide potential range. Consequently, an ultra‐high and stable H2O2 yield of up to 67.9/51.2 mol g−1 h−1 has been achieved on this material at a current density of 200/120 mA cm−1, corresponding Faradaic efficiency of 72.8/91.5%. A maximum H2O2 concentration of 13.47 g L−1 can be accumulated at a current density of 80 mA cm−1 with satisfactory stability. The strategy of surface active site densification thus provides a promising and universal avenue toward designing highly active and efficient electrocatalysts for 2e−‐ORR as well as a series of other similar electrochemical processes.