A Cu/CuFe2O4-OVs two-electron centre-based synergistic photocatalysis-Fenton system for efficient degradation of organic pollutants

To promote the separation of photogenerated carriers, break through the bottleneck of classical Fenton reaction, and achieve the efficient degradation of organic pollutants, a two-electron centre Cu/CuFe2O4 with oxygen vacancies (Cu/CuFe2O4-OVs)1 was synthesised by citric acid complexation and ascorbic acid (Vc)2 in-situ reduction. Under visible light irradiation, H2O2 was added to form a two-electron centre synergistic photocatalysis-Fenton degradation system that could degrade 100 ppm of phenol by 92.72% in 18 min. The degradation efficiency constant was 8165 and 4.35 times that of photocatalysis and Fenton oxidation, respectively. Such excellent degradation activity is attributed to the synergistic effect of the two-electron centre and photocatalysis-Fenton. Cu0 has two functions: (1) it acts as an electronic bridge of Fe and Cu in Fenton and accelerates the separation of photogenerated carriers; (2) it acts as the transfer channel of the two-electron centre. Oxygen vacancies are electron-rich centres that activate H2O2, while the electron-poor centre Cu(II) captures photogenerated electrons and phenol electrons. Quenching experiments and EPR results indicated that OH, O2− and h+ are the main active species. The synergistic degradation mechanism was proposed based on experiments and theoretical calculations. Through further optimization of the conditions and cyclic regeneration stability test, the system was extended to degrade different dyes, phenolic organic pollutants and coking wastewater.