Metal-free carbon-nitrogen@carbon-type hybrid electrocatalysts for peroxide-producing oxygen reduction reaction

Abstract

Hydrogen peroxide (H2O2) is a widely utilized chemical in environmental cleaning, medical disinfection, and chemical engineering. Compared to the traditional anthraquinone oxidation method, the electrocatalytic oxygen reduction reaction (ORR) has become a promising alternative following the trends towards decentralized production schemes for base chemicals as well as the implementation of renewable energy sources to drive chemical reactions. ORR is attractive for the production of H2O2 due to its environmental friendliness, safety, and reliability. However, its wider application is still restricted by the sluggish reaction kinetics and low selectivity due to the competitive reaction of the oxygen reduction to H2O. In this context, nitrogen-rich carbon electrocatalysts with tunable adsorption properties and high electrical conductivity are promising materials for improved selectivity. A precise tailoring of their chemical structure is however required to embed peroxide-producing catalytic sites within a conductive environment. Herein, a metal-free carbon-nitrogen (CN)-type nanoporous carbon loaded onto a carbon matrix (CN@C) was designed as an ORR catalyst for highly selective peroxide synthesis in alkaline media. An average electron transfer number of 2.2 has been determined by the Koutecký–Levich analysis, indicating that CN@C materials exhibit a high selectivity for electrochemical H2O2 synthesis.