Fast and simplified synthesis of cuprous oxide nanoparticles: annealing studies and photocatalytic activity

We synthesized highly (111) plane-oriented cuprous oxide (Cu2O) nanoparticles (NPs) by a fast and simplified chemical deposition method using an inorganic process at ambient temperature. The variations of crystal structure parameters, morphology, energy bands, and Brunauer-Emmett-Teller (BET) surface areas were recorded for Cu2O NPs at different annealing temperatures under N-2 atmosphere. A phase coexistence of Cu2O and Cu was observed after the Cu2O NPs was annealed at 600 degrees C for 2 h under N-2 atmosphere. The Cu2O NPs show high BET surface areas and a blue shift of absorption edge in comparison with Cu2O microparticles. We observed a superior photocatalytic activity for the degradation of methyl orange (MO) by Cu2O NPs, which reached 100% in 55 min with as high as 7.26 mg min(-1) g(-1) of decolorization rate. However, Cu2O NPs are more vulnerable to photocorrosion than Cu2O microparticles. The mechanisms of photocatalysis for Cu2O under visible light were also discussed in detail. Hydrogen peroxide and hydroxyl radicals were found responsible for the decolorization of MO.