Oxidation power-opportunity coupling enables interfacial-to-bulk relay mineralization of PFOA via an in-situ heterojunction anode and single-atom oxidative nodes.

Abstract

Deep PFAS mineralization remains constrained by the mismatch between strong interfacial oxidation power and insufficient bulk-phase oxidation opportunity for fluorinated intermediates, causing incomplete defluorination despite efficient parent-compound degradation. Here, we establish an oxidation power-opportunity coupling framework through an interfacial-to-bulk oxidative relay strategy by integrating an in-situ phase-transformed MXene-derived Ti3C2/Ti4O7 heterojunction anode (MTO) with Co single-atom-engineered Ti-MOF oxidative nodes (CoSACs-TIM). The chemically integrated Ti-O-C heterointerface enhances interfacial oxidation power by accelerating charge transfer, increasing reactive Ti site accessibility, and promoting •OH generation, while suspended Co single-atom oxidative nodes activate peroxymonosulfate under visible light to continuously create bulk-phase oxidation opportunities for reactive intermediates generated after initial anodic activation. Consequently, the coupled system achieves 98.1% PFOA degradation, 68.4% defluorination, stable operation over 120 h of continuous-flow treatment, and favorable techno-economic and life-cycle performance. Mechanistic investigations combined with DFT calculations reveal that deep mineralization originates from the synergistic coupling of enhanced interfacial oxidation power and expanded bulk oxidation opportunity. Quantitative descriptor analysis further demonstrates that PFAS mineralization is jointly governed by oxidation power and oxidation opportunity, rather than either oxidation dimension alone. This work establishes a catalytic framework for overcoming the mineralization bottleneck of persistent contaminants through spatially integrated interfacial and bulk oxidation.

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