Oxide heterojunction with stable and dense interface induced by magnesium aluminum oxide spinel for high-efficiency electrosynthesis of hydrogen peroxide.

Two-electron oxygen reduction reaction (2e ORR) is a low cost and high security method for the electrosynthesis of hydrogen peroxide (HO). Nevertheless, the 2e ORR selectivity and activity are difficult to control. Herein, a MgAlO/CoO heterojunction electrocatalyst has been successfully synthesized by the calcination of layered double hydroxide (LDH). As a 2e ORR electrocatalyst, the MgAlO/CoO demonstrates a high HO selectivity of 90 % with excellent stability. In a flow cell, the MgAlO/CoO electrocatalyst exhibits a HO yield of 10.2 mol g h and a faradaic efficiency of 85 %. Experimental results reveal that the MgAlO spinel is conducive to the high dispersion of metal and stable structure of catalyst. The stable and dense heterojunction interface can be induced by the MgAlO spinel in the MgAlO/CoO, ultimately leading to the high activity and stability of catalyst. Density functional theory (DFT) calculations uncover that the construction of MgAlO/CoO can facilitate charge transfer and adjust the electronic structure, thereby promoting the 2e ORR selectivity for high-efficiency HO production. Additionally, the HO generated by the MgAlO/CoO electrocatalyst can achieve in-situ degradation of rhodamine B. The possible degradation pathway is also proposed. This strategy provides a reasonable way to prepare 2e ORR electrocatalysts for HO production toward pollutant degradation.