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Excessive energy consumption and low reaction efficiency caused by electron cycle rate limitations are bottlenecks in water treatment. Here, we introduce an innovative strategy to overcome this problem viaconstructing a novel three-dimensional (3D) hybrid of vanadium tetrasulfide cross-linking graphene-like carbon with π electrons (VSO–C(π)), which exhibits excellent performance during refractory pollutant removal based on sustainable electron cycling between hydrogen peroxide (H2O2), dissolved oxygen (DO), and pollutants at the solid–liquid micro-interface. VSO–C(π) is synthesized through an in situhydrothermal synthesis procedure and characterized viaa series of techniques. The cation-π structures are constructed through V–S–C(π) and V–O–C(π) bridges in VSO–C(π), triggering orientable electron transfer from C(π) to the metal V centers and forming a polarized distribution of surface electrons. In the VSO–C(π)/pollutants/DO/H2O2system, the pollutants act as electron donors to C(π), with the subsequent degradation of pollutants, while DO and H2O2act as electron acceptors and are activated by reactive oxygen species to further degrade the pollutants at the V centers. This sustainable electron cycling process is responsible for the excellent activity and superior adaptability to pH changes and different salt environments, while also greatly saving resources and reducing energy consumption.

The discharge of organic pollutants threatens the environment and health and is also a waste of organic energy. Here, the reduction state Cu (RSC) species-doped carbon–nitrogen–oxygen polymer (RSC-CNOP) is synthesized from high-temperature polymerization of a Cu-polyimide precursor, which is used as a Fenton-like catalyst and exhibits excellent performance for pollutant degradation, accompanied by the utilization of the electron energy of the pollutants. Experiments and theoretical calculations reveal the promotion mechanism. The formed Cu(RSC)–O–C(π) electron-transfer bridges in RSC-CNOP induce the bidirectional electron transfers from RSC to O and from C(π) to O (RSC → O ← π), forming the polarized reaction micro-areas (reinforced electron-rich O microcenters and electron-poor C(π) microcenters). The free electrons in electron-rich centers of RSC-CNOP are as many as ∼8 times that of the pure CNOP sample from the electron paramagnetic resonance measurement. Pollutants are oxidized by supplying electrons to electron-poor microcenters, and H2O2can be selectively reduced to •OH (also destruct pollutants) in the electron-rich microcenter over RSC-CNOP. This work reveals that the energy and electrons of pollutants can be efficiently utilized in the Fenton-like system through constructing and reinforcing the polarized dual reaction microcenters.

Cu-Doped mesoporous polyimide nanocomposites (Cu-MP NCs) are developed viaan in situdoping and hydrothermal polymerization method for the first time, which shows high activity and efficiency for refractory pollutant degradation, through a Fenton-like process in a very wide pH range (2.6–10.4). The reaction rate for pollutant removal is 15–21 times higher than that of the conventional Fenton catalyst. Based on the experimental and theoretical results, Cu+and Cu2+exist on the surface of Cu-MP NCs and bond with the aromatic rings of the polyimide substrate, through C–O–Cu bonding bridges, which induce cation–π interactions and result in the formation of electron-rich centers around Cu and an electron-deficient center on the bonding aromatic rings. During Fenton-like reactions, the π–π stacking between the aromatic rings of Cu-MP NCs and the aromatic rings of pollutants results in the adsorption and electron-donation of pollutants on the electron-deficient centers of Cu-MP NCs. This serves to inhibit H2O2overoxidation and further accelerates the electron transfer cycles from the electron-deficient centers to the electron-rich centers through π → cation interaction viaa C–O–Cu bridge and from the electron-rich centers to H2O2with the generation of OH.