Enhanced photocatalytic activity of p-n-n heterojunctions ternary composite Cu2O/ZnO/Ag3PO4 under visible light irradiation

In this work, a ternary composite Cu2O/ZnO/Ag3PO4 with p-n-n heterojunctions was prepared via co-precipitation method. Single and binary counterparts were also prepared under similar conditions for comparison. The as-obtained photocatalytic materials were characterized by AAS, XRD, SEM-EDX, Uv-vis, PL, FTIR and BET techniques. Presence of the three oxide components in the composite was confirmed from AAS, XRD and EDX analyses. The calculated band gap of the composite (2.15 eV) demonstrated how formation of hetrojunction influenced the band gap of the host semiconductor ZnO (3.18 eV). Photocatalytic degradation activity of the composite under visible light irradiation was evaluated in aqueous solution comprising a model dye pollutant methyl orange (MO) and on a real sewage sample solution collected from Bahir Dar Textile Share Company. The ternary composite, Cu2O/ZnO/Ag3PO4, has shown relatively higher photodegradation efficiency on both Methyl orange (MO) (81.1 %) solution and textile effluent (78.2 %) compared with its single and binary congeners. This clearly indicates that the multiple heterojunction created a condition that favors the enhancement of MO dye degradation. The ternary heterojunction showed prolonged delay of electron-hole recombination, which is responsible for its highest photocatalytic efficiency as confirmed from results obtained from PL and trapping experiment.