Interfacial effect of the nanostructured Ag2S/Co3O4 and its catalytic mechanism for the dye photodegradation under visible light

In this study, the synthesis of a highly hybrid, heterogeneously structured nanocomposite catalyst consisting of Ag 2 S nanoparticles dotted on a Co 3 O 4 microrod array is reported. The average diameter and length of the Co 3 O 4 microrods was optimized to be approximately 300   nm and 20   μm, respectively, and the average size of the Ag 2 S nanoparticles was approximately 10   nm. When the Ag 2 S nanoparticles were deposited on the Co 3 O 4 microrods, the characteristic optical band gap energy of Co 3 O 4 decreased from 1.26   eV to 1.23   eV, and the intensity of the absorbance peak at 650   nm increased significantly. The catalytic activity of nanosized Ag 2 S/Co 3 O 4 for the photodegradation of organic contaminants with potassium hydrogen persulfate (PMS) or ozone (O 3 ) was evaluated using basic green 1 dye (BG1) as a model pollutant. In the presence of the hybrid Ag 2 S/Co 3 O 4 catalyst developed in this study, the complete photodegradation of the BG1 solution was achieved in 20   min and 6   min when PMS and O 3 were used, respectively. In addition, the experimental results suggest that the catalytic photodegradation of BG1 using the Ag 2 S/Co 3 O 4 /PMS and Ag 2 S/Co 3 O 4 /O 3 processes was dominated by the OH and O 2 − radicals, respectively.