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

A heterogeneous nanocomposite catalyst constructed by the Co 3 O 4 nanorods decorated with the Cu 2 O quantum dots (QDs) were successfully synthesized via a simple hydrothermal method followed by an oxidation-reduction processing. The fabricated Cu 2 O/Co 3 O 4 nanocomposite was characterized by the SEM, TEM, XPS, XRD, UV–vis and PL, and the (2   2   0) and (3   1   1) facets of the Co 3 O 4 were exposed. Compared with the original Co 3 O 4 nanorods with an average diameter of 350   nm, a substantial decrease in the band gap was observed after doping the nanorods with the Cu 2 O QDs (average diameter of 5   nm). 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 Cu 2 O/Co 3 O 4 nanocomposite catalyst exhibited both high catalytic activity and good recycling stability. The catalytic activities of the Cu 2 O/Co 3 O 4 /potassium monopersulfate triple salt (PMS) system for cleaving the MB and the phenol were dependent on the dosages of the Cu 2 O QDs, and the calculated degradation rates achieved by 7.0   wt% Cu 2 O/Co 3 O 4 nanocomposite catalyst were about 11.3 and 1.8 times than that of the pristine Co 3 O 4 nanorod catalyst for the MB and the phenol, respectively. The reactive species of O 2 − and the holes were determined to be the main active species for the phenol photocatalytic degradation by the 7   wt% Cu 2 O/Co 3 O 4 /PMS system and the 7   wt% Cu 2 O/Co 3 O 4 /H 2 O 2 system, respectively.