Renewal of Cu-Fe dual active sites in Z-scheme heterojunction for efficient photo-assisted Fenton water decontamination: Enhanced electron transport and minimized environmental biotoxicity.

Photo-assisted heterogeneous Fenton reaction continues to hold great promise as a highly effective method for rapid water decontamination, but its actual practice is still limited by the slow renewal of active sites on catalysts. Herein, we have ingeniously combined copper silicate nanotubes (CSN) and Fe2O3 to construct Fe2O3/CSN Z-scheme heterojunction with Cu-Fe dual active sites and oxygen vacancies (Vo) for efficient elimination of organic contaminants through photo-assisted Fenton reaction. Experimental results reveal that interfacial Vo produced from lattice mismatch between Fe2O3 and CSN induces the generation of low-valent Fe(Ⅱ)/Cu(Ⅰ) sites for the cleavages of H2O2, while promoting the adsorption of H2O2 on metal sites to facilitate H2O2-triggered reduction of Fe(III)/Cu(Ⅱ) to produce •O2-. The thermodynamically advantageous electron migration driven by interface interactions ensures the reduction of Fe(Ⅲ) by Cu(Ⅰ), accelerating Fe(Ⅲ)/Fe(Ⅱ) and Cu(Ⅱ)/Cu(Ⅰ) cycles. The intrinsic electric field drives the photogenerated electrons transport through the Cu-O-Fe bridge from CSN to Fe2O3, further enhancing the regeneration of Fe(Ⅱ). These contributions collectively expedite the renewal of dual active sites and eventually enhance H2O2 activation, realizing 100 % removal rate of bisphenol A in 15 min via photo-assisted Fenton process, with a catalytic activity 14 and 26 times greater than that of Fe2O3 and CSN, respectively. Furthermore, it exhibits 78 % chemical oxygen demand removal in actual wastewater (2882.8 mg/L) within 180 min via a continuous-flow reactor, demonstrating attractive potential for advanced real-world wastewater treatment. This study offers a practical and feasible solution for efficiently removing organic pollutants during water treatment.