Preparation Of Cu₂O With Different Morphology And Study On Its Photocatalytic Performance

With the acceleration of urbanization and industrialization,environmental and energy problems are becoming more and more obvious.Solar energy is green and clean.If it can be used effectively,these problems can be controlled.Photocatalytic materials can be used for generating hydrogen or oxygen through water splitting,reducing carbon dioxide to alleviate the greenhouse effect,and decomposing pollutants.Since 1972,researchers all over the world have begun to pay attention to the preparation and rational development of photocatalysts.Cuprous oxide has a narrow band gap,usually around 2.0 eV,which can absorb and utilize a wide range of sunlight.Common research applications include photohydrolysis of water and degradation of pollutants.However,the common Cu₂O photocatalytic effect of cubic morphology is not good,and its application is limited.Some studies have demonstrated that the photocatalytic performance of cuprous oxide is related to morphology.Therefore,we first explored the factors affecting the morphology of Cu₂O in the process of preparing Cu₂O through multiple groups of comparative experiments,and then we successfully synthesized six types of Cu₂O,including spherical Cu₂O,cubic Cu₂O,dodecahedral Cu₂O,tetradecahedral Cu₂O,twenty-six hedral Cu₂O and big spherical Cu₂O consisting of small cubes by different experimental schemes,changing the precursor,reducing agent and their concentration,adding surfactant and changing the temperature.The Cu₂O samples with six morphologies all had narrow band gaps and excellent light absorption capacity.The absorption of light can reach 600 nm.Among them,the dodecahedral Cu₂O and spherical Cu₂O had a fast speed for electron and hole to separate,and excellent photocatalytic degradation ability of methyl orange dye.Under the irradiation of white LED lamp,the degradation efficiency of 40 min reached 83%and 65%respectively.Through free radical capture experiments,it was found the active substances that Cu₂O samples depend on during degrading MO are·O₂^-and h⁺.The morphology of spherical cuprous oxide was different from that of common polyhedral cuprous oxide.We set five experimental preparation temperatures of 50°C,60°C,80°C,90°C and 100°C respectively to further discuss the influence of temperature on the experimental preparation and photocatalytic performance of spherical cuprous oxide.The results showed that a single Cu₂O phase was prepared at50℃,60℃and 80℃,with spherical morphology.Among them,60℃was the best synthesis temperature of this preparation method.The Cu₂O sample synthesized at this temperature had the most uniform morphology,the smallest size,the fastest separation and transfer speed of photogenerated carriers,and its performance of photocatalytic degradation of methyl orange was the best.Besides,it had good stability.The samples prepared at 90℃and 100℃were both mixture of spherical Cu₂O and fragments of Cu elemental substance.Moreover,the photocatalytic performance of all the mixed samples was not as high as that of pure Cu₂O samples synthesized at lower temperature.