Constructing a Gas–Solid Interfacial Electro-Fenton Reaction System for Achieving Efficient Ambient Toluene Mineralization

Electro-Fenton (E-Fenton) technology is recognized as an efficient strategy for hydroxyl radical (•OH) generation through O2 activation, enabling effective organic pollutant degradation. However, its performance is fundamentally limited by mass transfer constraints related to the low solubility and slow diffusion rate of oxygen in aqueous media. These limitations restrict H2O2 production via 2e– oxygen reduction (ORR), resulting in suboptimal •OH yields and prolonged reaction times, particularly for hydrophobic organic pollutants. Here, we established a gas–solid interfacial E-Fenton system based on a membrane electrode assembly (MEA), which allows for the direct gas-phase reactant delivery to catalytic interfaces, thus overcoming aqueous solubility limitations of O2 and pollutants. We employed a hydrophobic Nafion-modified TiO2 nanotube array (TNA) as a cathode, which significantly improves the electrode’s oxygen affinity, achieving a dynamic equilibrium between active hydrogen generation and its timely consumption by oxygen intermediates through maximizing O2 coverage at active sites. Using gaseous toluene oxidation as a model reaction, this system achieved 100% toluene (10 ppm) mineralization at −3 V bias and ambient temperature. The proposed gas–solid interfacial E-Fenton system offers a promising solution for low-concentration VOC treatment under ambient conditions.