A high-performance room temperature thermocatalyst Cu2O/Ag0@Ag-NPs for dye degradation under dark condition

Abstract

A series of Cu2O/(Ag0@Ag-NPs)x(x = 0.0–0.25) thermocatalysts were synthesized via one-step reaction of Cu2+ and Ag+ ions with glucose in alkaline solution. The morphological, structural, optical and electrochemical properties of the thermocatalysts were investigated in detail. The results reveal that Cu2O and metallic Ag grow together to form a composite core (Cu2O/Ag0), while the core surface was coated by metallic Ag nanoparticles (Ag-NPs) as a shell. Owing to the imperfection of surface lattice of Cu2O caused by close contacting with metallic Ag, a new interface state level generates in the band gap of Cu2O. Moreover, Ag-NPs shell exhibits strong thermal radiation effect and surface plasma resonance (SPR) effect, so Cu2O/Ag0@Ag-NPs catalyst can be activated by absorbing heat energy. Due to the action of Schottky barriers, electrons easily migrate to the surface and combine with O2 to generate O2− radicals. Therefore, Cu2O/Ag0@Ag-NPs thermocatalyst can efficiently degrade high concentration dye (200 mg/L Acid Orange 7) under dark condition at room temperature. The mechanism study proved that O2−, eCB− and hVB+ play critical roles in the degradation of AO7. Electrons (eCB−) activated by heat energy react with O2 to generate O2− radical, O2− radicals induce the degradation reaction, while surplus holes (hVB+) react directly with dye. The experimental result of different irradiation source shows that Cu2O/(Ag0@Ag-NPs)x materials are high-performance thermal and photo catalysts, implying promising application in the degradation of dye wastewater on an industrial scale for all day operation.