Upcycling of Aqueous Phenol Pollutants via Directed C–C Coupling in an Enzyme-Inspired Angstrom-Confined Flow-Through System
Cuiwei Du, Wanyi Fu, Jie Li, Hui Xu, Bingcai Pan
Abstract
Selective transformation of phenol in wastewater into value-added products offers a sustainable strategy for simultaneous pollutant abatement and chemical resource recovery. However, conventional oxidation processes suffer from low product selectivity due to competing pathways, including ring-opening degradation, C-C/C-O coupling, and polymerization. Here, we develop an angstrom-confined flow-through system using laminar membrane nanochannels to enable spatiotemporally controlled oxidation and regioselective C-C coupling. The 6.0 Å interlayer spacing of ZnFe-layered double hydroxide enforces stereoselective alignment of phenoxy radicals, while flow modulation precisely regulates the reaction progression. This enzyme-inspired dual-control strategy achieves 84% C-C selectivity at 50% phenol conversion and suppresses parasitic pathways (C-O coupling, overoxidation) that are endemic to traditional batch systems. Mechanistic studies and density functional theory (DFT) calculations reveal that nanoconfinement thermodynamically stabilizes para-oriented radicals, steering barrierless C-C coupling. Integrated with selective resin adsorption for biphenol harvest and phenol recycling, up to 90% cumulative product yield is achieved. This work establishes a low-carbon pollutant-to-product paradigm for resource recovery from contaminated waters.