Durable Ti<sub>4</sub>O<sub>7</sub> Heterojunction Composite Membrane Encapsulating N-Doped Graphene Nanosheets for Efficient Electro-Oxidation of GenX and Other PFAS in Fluorochemical Wastewater
Yiyang Liang, Anqi Wang, Shangtao Liang, Kai Sun, Ruzhen Xie, Ce Zheng, Sihan Zhang, Caiming Tang, Dengmiao Cheng, Jinxia Wang, Qingguo Huang, Hui Lin
Abstract
Rational interfacial engineering design of an electrocatalyst, such as a heterojunction structure, can effectively enhance its catalytic activity. This study aims to address a critical challenge associated with the use of carbon material@Ti 4 O 7 heterojunction composite electrodes for wastewater treatment─electrode stability over long-term operation. Herein, we report a highly stabilized interfacial engineering strategy, i.e., the use of conductive inorganic CeO 2 as a “cement” to firmly encapsulate N-doped graphene oxide nanosheets (N-GS) on the Ti 4 O 7 surface. The defect-rich N-GS encapsulated on the Ti 4 O 7 surface significantly enhances interfacial charge transfer. This enhancement results in the N-GS/CeO 2 @Ti 4 O 7 heterojunction composite electrode exhibiting excellent efficiency in the electro-oxidation of hexafluoropropylene oxide dimer acid (HFPO-DA or GenX). Furthermore, a flow-through N-GS/CeO 2 @Ti 4 O 7 reactive electrochemical membrane system effectively mineralizes other 35 PFASs in a real fluorochemical wastewater sample, achieving a high defluorination rate of 70–90% and exhibiting better performance in PFAS destruction and energy efficiency compared to the UV/KI-SO 3 2– process. Results of this study enhance our understanding of the electrochemical oxidation of PFAS and offer valuable insight into the design of stabilized Ti 4 O 7 heterojunction composites. These findings are instrumental in advancing the development of effective treatments for PFAS-contaminated environments.