Engineering High-Entropy Interfaces in a Single-Metal Cu System to Drive Concerted Nonradical Catalysis and Pollutant Sequestration

Abstract Nonradical direct electron transfer (DET) can make advanced oxidation less vulnerable to radical scavenging in complex waters, but requires catalysts with efficient charge transport, stability, and practical synthesis. High-entropy materials provide diverse local environments, yet their multimetal compositions and prolonged heat treatment limit implementation. We combined chemically induced self-internal heating (SIH) with chloride-induced interfacial reconstruction to prepare a single-metal Cu system with high-density grain boundaries (SM-HDGB). SIH formed a Cu-carbon precursor in 3.5 s through an internal pulse above 1200 °C. HCl treatment generated intergrown Cu, Cu2O, CuCl, and Cu2Cl(OH)3 domains spaced 2–10 nm apart, creating phase, oxidation-state, and coordination diversity described as empirical interfacial chemical-state entropy. SM-HDGB completely removed tetracycline within 10 min and increased the apparent rate constant 9.88-fold over the precursor, with little response to 10 mM coexisting anions. Electron paramagnetic resonance, scavenging, filtration, electrochemical, and in situ spectroscopic evidence supported predominantly surface-confined, catalyst-mediated DET. In packed-bed operation, SM-HDGB maintained more than 80% COD removal across four regeneration cycles (approximately 130 h), retained pollutant-derived organic products, and produced near-neutral effluent compatible with Chlorella growth. Laboratory-scale screening estimated at least 96.3% lower synthesis energy demand than conventional routes. Chemical-state-diverse single-metal interfaces can therefore couple rapid peroxydisulfate activation with stable continuous-flow treatment.