Synergistic photocatalytic performance of cobalt tetra(2-hydroxymethyl-1,4-dithiin)porphyrazine loaded on zinc oxide nanoparticles.

A new ZnO/CoPz(hmdtn)4 composite as a highly efficient photocatalyst was successfully prepared by cobalt tetra(2-hydroxymethyl-1,4-dithiin)porphyrazine (CoPz(hmdtn)4) impregnated onto the surface of ZnO nanoparticles, the photocatalytic performance of ZnO/CoPz(hmdtn)4 under both simulated sunlight and visible light (λ ≥ 400 nm) irradiation was assessed by degradation of Rhodamine B (RhB) and phenol in aerated conditions. The ZnO/CoPz(hmdtn)4 manifested much higher photocatalytic activity than pure ZnO and pure CoPz(hmdtn)4, originating from the synergistic effect between CoPz(hmdtn)4 and ZnO. Furthermore, the XPS analysis revealed that there may be strong interaction between CoPz(hmdtn)4 and ZnO. Thereby ZnO/CoPz(hmdtn)4 with excellent stability can maintain high photocatalytic activity over five runs on the basis of the reusability test. The active species generated in the photocatalytic system were verified by electron spin resonance (ESR) technology. A possible mechanism of the synergistic effect between CoPz(hmdtn)4 and ZnO was also proposed.