Boosted HO activation for water decontamination via biomass carbon dots/WO composites: The role of Z-scheme charge transfer pathway and dual reaction centers.

Photo-Fenton-like catalytic reactions exhibit remarkable effectiveness in environmental remediation owing to the synergistic interaction between photocatalysis and peroxide activation. Herein, biomass carbon quantum dots (BCDs) derived from pomelo peels were used to modulate BCDs/WO (BW) composites with dual reaction centers via a microwave-induced solvothermal approach, forming an iron-free photo-Fenton-like system (PFLS). Driven by the built-in electric field across the BW heterointerface, a Z-scheme charge transfer route was elucidated, which endows rapid photoexcited electron transfer from the WO to the BCDs. Notably, the dual reaction centers on BCDs and electron-rich oxygen vacancies of WO acted as both electron transmission "channel" and electron "reservoir", thereby accelerating the redox cycle of W/W to phenomenally enhanced production of O and ·O species involving interfacial reactions. Simulated adsorption and cleavage behaviors of HO on BW revealed a lower Gibbs free energy difference (ΔG) for O evolution (1.90 eV) compared to ‧OH (4.10 eV) evolution. The optimal BW-10 PFLS is efficient in various pollutants removal, with the maximum degradation rate constant (k) for RhB being 25.9 and 6.4 times higher than that of conventional Fenton-like and photocatalytic systems, respectively. It also exhibited outstanding synergistic degradation performance with 83.2 % TC-HCl and 98.6 % RhB removal in their mixed solution. Meanwhile, the BW-10 PFLS had excellent recyclability and anti-interference capability in complex real water matrices. Additionally, the bean sprout growth experiments demonstrated the negligible toxicity of the degradation products in the BW-10 PFLS. This work provides a fresh insight into the design of WO-based photo-Fenton-like photocatalysts for environmental remediation.