Preparation And O₂-Cathode Properties Of Nano-Cu₂O Oxidized From Cu Colloids

Nanomaterials have become the investigative point in science because of its special structure and superior characters, especially in photo-catalysis field. The rapid progress of nano-technology gives a good opportunity to the application of nano-photocatalysis technology. At present, TiO₂ and ZnO are usually used as photo-catalysts. But they can only be excited by ultraviolet. Costly problems are the obstacle for its industrialization due to the UV light source. Fenton regent has been studied widely because it can generate·HO which has strong oxidizability. But this kind system is not used widely because it costs much H₂O₂ and electrical energy.Cuprous oxide (Cu₂O) is low-cost and can be excited by visible light due to the narrow band gap of 2.1eV. In 1998, Ikeda firstly showed that micron-sized Cu₂O might be employed as a promising catalyst under visible light. But the light generated charge carriers in micron-sized Cu₂O grains are easily lost due to recombination. Reducing Cu₂O grains size can greatly improve the photo-catalysis ability of Cu₂O. We found an extraordinary way to prepare Cu and Cu₂O nano-particles. The copper colloid was successfully formed and subsequently oxidized in ambient air to form stable and easily dispersed cuprous oxide nano-particles. Different morphologies of cuprous oxides were synthesized in different disperse mediums. The products have been characterized and analyzed by X-ray diffraction, Scanning electron microscope and UV-visible absorption spectrum etc. The reaction mechanism has been discussed. Our work also shows that the Cu₂O nano-particles absorb much oxygen on their surface as described in the paragraph of TG-DSC, EDS and XPS observation.The Cu₂O could be a promising material as oxygen-cathode in an electrochemical cell system. So we investigated oxygen-cathode properties of spherical Cu₂O nano-particles. The formation of H₂O₂ has been confirmed by electrochemical method. The experimental results show that the nano-Cu₂O oxygen-cathode is a good catalyst for oxygen reducing reaction. Oxygen can be easily reduced to H₂O₂ in low voltage.We utilized it as new Fenton system to degrade dye-brilliant red X-3B. The results show that this kind of system can effectively degrade dye-brilliant red X-3B. We also found that light can improve the degradation.