Hydrogen peroxide (H2O2) is a vital green oxidant with broad applications ranging from disinfection to chemical manufacturing. However, its industrial production remains heavily reliant on the energy-intensive and waste-generating anthraquinone process. The electrochemical two-electron oxygen reduction (2e− ORR) offers a sustainable alternative, enabling on-site H2O2 generation powered by renewable electricity. While acidic conditions align better with application scenarios, developing efficient and stable non-precious metal catalysts for acidic 2e− ORR has proven to be challenging.
Recently, the research team led by Prof. Jianfeng Jia from Shanxi Normal University has unveiled a breakthrough in electrochemical H2O2 synthesis. The study, published in Science Bulletin, reports a novel catalyst, Cr–N4/C(O), which composed of isolated Cr atoms anchored on a N-doped carbon matrix and further modified with O-functional groups.
The research journey began with molecular dynamics simulations, which uncovered a unique "self-adjusting" mechanism. Contrary to the long-held belief that CrN4 structures bind oxygen too strongly for effective catalysis, the team found that the pyrolyzed Cr–N4 site spontaneously coordinates with an axial oxygen atom during the reaction. This self-formed structure fine-tunes the site's electronic properties, effectively preventing it from oxygen poisoning and enabling the reaction to towards H2O2.
Guided by this theoretical insight, the team synthesized the catalyst using a confinement strategy to ensure atomic dispersion of Cr. A subsequent mild thermal treatment in air introduced oxygen functional groups onto the carbon substrate. This peripheral engineering was crucial, creating an electron-deficient Cr center. The synergistic effect between the axial and peripheral O atoms optimized the interaction with O2 molecules, stabilizing the O–O bond and steering the reaction selectively toward H2O2 formation. The Cr–N4/C(O) catalyst demonstrates highly efficient, selective, and stable H2O2 electrosynthesis in acidic media. It outperforms conventional Co-based catalysts by effectively suppressing H2O2 reduction, retarding its decomposition, and exhibiting enhanced metal-leaching resistance.
This research not only identifies a compelling new catalyst candidate for acidic 2e− ORR catalysis but also offers a novel perspective on designing catalysts with self-adaptive features.
