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

Abstract

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 N₂ atmosphere. A phase coexistence of Cu₂O and Cu was observed after the Cu₂O NPs was annealed at 600 °C for 2 h under N₂ 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.