Interfacial effects of the Cu2O nano-dots decorated Co3O4 nanorods array and its photocatalytic activity for cleaving organic molecules

[Display omitted] •Co3O4 rods were grown on plasma treated Ti foil.•Cu2O QDs were uniformly distributed on the surface of nanorods.•Ti/Co3O4/Cu2O exhibited visible light photocatalytic activity with KHSO5.•Degradation mechanism was supported by ESR technique and radical scavenger tests.•The heterojunction was highly stable even after recycling many times. A heterogeneous nanocomposite catalyst constructed by the Co3O4 nanorods decorated with the Cu2O quantum dots (QDs) were successfully synthesized via a simple hydrothermal method followed by an oxidation-reduction processing. The fabricated Cu2O/Co3O4 nanocomposite was characterized by the SEM, TEM, XPS, XRD, UV–vis and PL, and the (220) and (311) facets of the Co3O4 were exposed. Compared with the original Co3O4 nanorods with an average diameter of 350nm, a substantial decrease in the band gap was observed after doping the nanorods with the Cu2O QDs (average diameter of 5nm). Such a dramatic decrease in the band gap indicated a significant enhancement of the photocatalytic activities under visible light. The methylene blue (MB) dye and the phenol were used as model organic pollutants, and the Cu2O/Co3O4 nanocomposite catalyst exhibited both high catalytic activity and good recycling stability. The catalytic activities of the Cu2O/Co3O4/potassium monopersulfate triple salt (PMS) system for cleaving the MB and the phenol were dependent on the dosages of the Cu2O QDs, and the calculated degradation rates achieved by 7.0wt% Cu2O/Co3O4 nanocomposite catalyst were about 11.3 and 1.8 times than that of the pristine Co3O4 nanorod catalyst for the MB and the phenol, respectively. The reactive species of O2− and the holes were determined to be the main active species for the phenol photocatalytic degradation by the 7wt% Cu2O/Co3O4/PMS system and the 7wt% Cu2O/Co3O4/H2O2 system, respectively.