Interface engineering of superhydrophobic octadecanethiol-functionalized hollow mesoporous carbon spheres for alkaline oxygen reduction to hydrogen peroxide

Abstract

Direct electrosynthesis by a two-electron oxygen reduction reaction (2e⁻ ORR) is an effective and promising synthetic method for producing H₂O₂. However, the rate of the oxygen reduction reaction is greatly limited by the slow transport of O₂. Interface engineering is an important means to control reactive microenvironments. Herein, we modified hollow mesoporous carbon spheres (HMCSs) with 1-octadecanethiol (ODT) to form a superhydrophobic interface, which provides an O₂-enriched surface layer at the catalytically active site and enhances O₂ adsorption. In 0.1 M KOH, the ODT-functionalized HMCSs (HMCSs@ODT) exhibits superior activity for H₂O₂ synthesis with 94.6% H₂O₂ selectivity across a wide potential range. During the electrolysis process, the hydrophobic interface can effectively release the H₂O₂ from the surface of the catalyst and prevent their further reduction to H₂O. In an H-cell system, HMCSs@ODT exhibits a remarkable H₂O₂ yield rate of 838.8 mmol g_cat.⁻¹ h⁻¹ and a notable faradaic efficiency of 95.2% at 0.365 V. The combination of the mesoporous structure and superhydrophobic interface provides a research idea for the electrochemical synthesis of H₂O₂.