Pauling-Type O2 Adsorption on a Cobalt Polyoxometalate for Efficient H2O2 Electrosynthesis from Oxygen Reduction

Abstract

Electrochemical two-electron oxygen reduction reaction (2e–-ORR) offers a sustainable route for green synthesis of hydrogen peroxide (H2O2). The development of relevant nonprecious metal catalysts with high performance and low cost is critical. Herein, we report a cobalt-centered Keggin-type polyoxometalate supported on amino-functionalized carbon nanotubes (Co-POM@NH2-CNTs), which functioned as an efficient 2e–-ORR catalyst to deliver a H2O2 selectivity of 92%, a current density over 100 mA cm–2, and a production rate of 5 mol gcat–1 h–1 in a flow cell. Mechanistic studies combining electrochemical analysis, Pourbaix diagrams, and DFT calculations reveal that the Co3+/Co2+ redox mediated electrocatalysis, with Co2+ sites properly stabilizing O2 and *OOH via a Pauling-type adsorption mode, which facilitated the 2e–-ORR pathway. This work highlights the critical influence of adsorption geometry on selectivity and positions Co-POM@NH2-CNTs as a potential catalyst for sustainable H2O2 synthesis.