Metastable Hexagonal Phase SnO2 Nanoribbons with Active Edge Sites for Efficient Hydrogen Peroxide Electrosynthesis in Neutral Media

Abstract

Electrochemical two-electron oxygen reduction reaction (2 e^- ORR) to produce hydrogen peroxide (H₂ O₂ ) is a promising alternative to the energetically intensive anthraquinone process. However, there remain challenges in designing 2 e^- ORR catalysts that meet the application criteria. Here, we successfully adopt a microwave-assisted mechanochemical-thermal approach to synthesize hexagonal phase SnO₂ (h-SnO₂ ) nanoribbons with largely exposed edge structures. In 0.1 M Na₂ SO₄ electrolyte, the h-SnO₂ catalysts achieve the excellent H₂ O₂ selectivity of 99.99 %. Moreover, when employed as the catalyst in flow cell devices, they exhibit a high yield of 3885.26 mmol g^-1 h^-1 . The enhanced catalytic performance is attributed to the special crystal structure and morphology, resulting in abundantly exposed edge active sites to convert O₂ to H₂ O₂ , which is confirmed by density functional theory calculations.

Keywords: Electrochemistry; Hydrogen Peroxide (H2O2); Metastable Compounds; SnO2; Two-Electron Oxygen Reduction Reaction (2 e− ORR).