Ionic liquid modified BiOCl/CNT catalyst with high hydrophobicity and aerophilicity for efficient electrosynthesis of hydrogen peroxide

Abstract

The electrochemical two-electron oxygen reduction reaction (2e⁻ ORR) is considered a promising method for the green synthesis of hydrogen peroxide (H₂O₂), but the design of a highly selective and active catalyst with both hydrophobicity and aerophilicity remains a challenge. In this study, we prepared a bifunctional hydrophobic–aerophilic catalyst (BiOCl/CNT)@NTF₂ by using ionic liquid (IL)-modified bismuth oxychloride and carbon nanotube composites (BiOCl/CNT). Unlike the nanosheet structure of pure BiOCl, the (BiOCl/CNT)@NTF₂ has a three-dimensional structure, which is due to the IL bonding BiOCl/CNT together through electrostatic and hydrogen-bonding interactions. The (BiOCl/CNT)@NTF₂ catalyst exhibited a high H₂O₂ selectivity of 95.1%, a cumulative H₂O₂ concentration of 6 wt%, and good stability during 120 h (12-cycles test, each cycle lasting 10 h) in an optimized continuous flow-cell reactor. The in situ ATR-SEIRAS results showed that (BiOCl/CNT)@NTF₂ enhanced the adsorption and activation of *OOH, contributing to its high selectivity for the 2e⁻ ORR. The contact angle test demonstrated that (BiOCl/CNT)@NTF₂ has a hydrophobic and aerophilic surface, providing it with strong flood-proof capability and enhancing the mass transfer of oxygen (O₂) at the three-phase interface. Furthermore, this study explored the possibility of on-site generation and application of H₂O₂ for the degradation of dyestuffs (MG, MB and RhB) with a degradation rate of 96%. This work highlights the favorable capability of (BiOCl/CNT)@NTF₂ in the practical production of H₂O₂, and provides an avenue for the design and fabrication of bifunctional hydrophobic–aerophilic catalysts for H₂O₂ production via electrochemical 2e⁻ ORR.