Local Acidic Microenvironment Construction via Alternating Current Electro-Fenton Process for Green Efficient Water Purification under Neutral Conditions

The direct current electro-Fenton (DCE-Fenton) process is limited by finite Fe species cycling, low H2O2 utilization rate, and stringent acidic pH requirements. In this study, a heterogeneous alternating current electro-Fenton (ACE-Fenton) process is proposed for the first time to achieve efficient pollutant removal under neutral conditions, leveraging enhanced Fe species cycling and the creation of a local acidic microenvironment to improve the H2O2 utilization efficiency and •OH generation efficiency. For different pollutants, the ACE-Fenton process operates efficiently at pH0 = 7 with a pseudo-first-order kinetics constant that is 5.1-6.3 times higher than that of the DCE-Fenton process and achieves a ∼20% reduction in removal time. Changes in the catalyst's coordination environment and valence states are analyzed via electrochemical in situ X-ray absorption fine structure spectroscopy and Raman spectroscopy. In situ electron paramagnetic resonance spectroscopy reveals the mechanism of •OH generation. Local pH fluctuations are monitored via the open circuit potential decay transients methodology. This work lays a theoretical foundation for the ACE-Fenton process, offering new insights into the design of green, efficient water purification systems.