Coupling functional anodes with natural air-diffused cathodes enables highly efficient hydrogen peroxide electrosynthesis

Abstract

目的 电化学合成过氧化氢(H_2O_2)是一种极具应用前景的分散式生产方法, 但因传统的单极电合成电流效率不高, 其发展受到了严重限制。本文旨在通过自组装单层膜修饰碳纤维纸制备高效二电子水氧化合成过氧化氢的阳极, 同时耦合负载聚四氟乙烯/炭黑的自然空气扩散阴极, 实现阴阳极同步电合成过氧化氢, 从而大幅度提高其电流效率。 创新点 1. 通过自组装单层膜修饰碳纤维纸制备功能化阳极高效二电子水氧化合成过氧化氢; 2. 耦合阳极和阴极大幅度提高电合成过氧化氢的电流效率。 方法 1. 利用自组装单层膜修饰碳纤维纸制备功能化阳极, 通过物化性能表征确定电极的结构特征(图1), 并通过活性、选择性等指标考察电极的二电子水氧化性能(图2); 2. 制备负载聚四氟乙烯/炭黑的自然空气扩散阴极, 并通过电化学性能表征确定最佳的物料配比(图3); 3. 耦合功能化阳极和自然空气扩散阴极, 并通过电流效率、产率、稳定性等指标评估体系电合成过氧化氢的性能(图4和表1)。 结论 1. 利用自组装单层膜修饰碳纤维纸制备高效的二电子水氧化阳极; 阳极过氧化氢的选择性为62.1%, 产率为12.6 µmol/(min·cm^2)。2. 确定自然空气扩散阴极上聚四氟乙烯与炭黑的比例为0.6, 并将其与功能化阳极耦合同步电合成过氧化氢, 所得电流效率高达152.9%, 且产率达到38 µmol/min。 Electrosynthesis of hydrogen peroxide (H_2O_2) is a decentralized production method with excellent application prospects. Coupling anodes with cathodes can achieve highly efficient electrosynthesis of hydrogen peroxide. In this study, we prepared an anode for H_2O_2 electrosynthesis via the two-electron water oxidation reaction (2e-WOR) by modifying carbon fiber paper with self-assembling monolayers. In addition, a natural air-diffused cathode loaded with polytetrafluoroethylene/carbon black using carbon cloth as substrate was prepared to combine with the modified anode to produce H_2O_2 simultaneously. The total current efficiency of the anode and cathode reached 152.9%, and the H_2O_2 production rate was as high as 38 µmol/min at 2.8 V vs. reversible hydrogen electrodes (RHE) in a Nafion 117 membrane-separated electrolyzer. This work reported a novel carbon-based 2e-WOR catalyst and laid a theoretical foundation for the simultaneous electrosynthesis of H_2O_2 with an anode and cathode.