High-current-density electrosynthesis of hydrogen peroxide via two-electron water oxidation on electronegativity strategy of ZnGaAlO4

A spinel oxide with low electronegativity Al substitution (ZnGaAlO₄) was designed. • The anode achieved 85.7% Faradaic efficiency and a 67.3 μmol cm −2  min −1 production rate for H 2 O 2 . • The introduction of Al enhances electron donation to HCO 3 − , significantly lowering the energy barrier. • The Al sites suppress OER intermediates (*O/*OOH), ensuring high 2e − WOR selectivity at high current densities. Electrochemical two-electron water oxidation reaction (2e − WOR) is a promising avenue for hydrogen peroxide (H 2 O 2 ) production. However, most reported anode materials suffer from insufficient selectivity and activity especially under high current density due to consequent competitive oxygen evolution reaction (OER). This seriously inhibits its industrial application. In this study, partially incorporating the octahedral sites (TM oct ) in spinel catalysts with low electronegativity elements like Al oct can effectively enhance the adsorption capacity of the 2e − WOR intermediate HCO 3 − , while the adsorption of OER intermediates (*O and *OOH) is inhibited. As a result, excellent H 2 O 2 selectivity of 85.7% and production rate of 67.3 μmol cm −2  min −1 are reached at a high current density of 250 mA cm −2 , which is much superior to that in most of the previous reports that hardly reached 120 mA cm −2 . This work reveals the regulatory mechanism of site electronic structure on reaction selectivity, providing a theoretical basis for developing highly efficient and stable 2e − WOR anodes under high current density conditions. Download: Download high-res image (221KB) Download: Download full-size image