Persulphate assisted photoelectrochemical degradation of organic pollutants in water on a silver nanoparticle modified Cu₂O photoanode

This work presents the photoelectrochemical production of sulphate radicals using fluorine-doped tine oxide – silver nanoparticles – copper(I) oxide (FTO-AgNPs-Cu₂O) photoanode in the presence of peroxydisulphate salt for the enhanced degradation of selected organic pollutants in water. Firstly, Cu₂O was prepared via a facile and template-free one-pot method, then AgNPs were photo-reduced on the surface of the Cu₂O, and the resultant product was immobilised on an FTO conductive substrate to form FTO-AgNPs-Cu₂O photoanode. When the electrode was applied for the abatement of tetracycline in the presence of 3 mM peroxydisulphate salt and 1.5 V external potential, the degree of tetracycline degradation and mineralisation after 90 min was 82 % and 78 % respectively. Furthermore, the same system was able to achieve degradation of 81 % sulfamethoxazole degradation within 90 min and 100 % orange II dye degradation within 30 min. The photoanode was efficient in the treatment of real wastewater containing tetracycline. Scavenger studies reveal that holes, hydroxyl, and sulphate radicals significantly participated in the degradation process. The electrode is stable and therefore applicable for the abatement of other organic pollutants in a persulphate-assisted photoelectrochemical degradation system.