Abstract
The morphology of crystal plays an important role to influence the band gap and the effect of catalysis has been announced. Based on this concept, the control of the morphology became an important issue. Cuprous oxide is a p-type semiconductor with a direct band gap about 2.17eV. It’s a potential material in photocatalyst and solar cell because of its high exciton binding energy and stability.We report a stable, low cost, nontoxic and high uniformity approach to manufacture the Cu2O powder. There’re four reactants in the experiment, which is the chelating agent, the reductant(glucose), the base(sodium carbonate) and the cupric ion(cupric nitrate). In this dissertation, it divides into three parts. In the first part, we try to find out the effect of the reagent concentration on the crystal morphology. By adjusting the citrate concentration, we demonstrate that the existence of chelating agent is crucial for producing well-crystallizing Cu2O particle. The higher glucose concentration would cause the twin-crystal because of the faster reducing rate. Besides, we observe an interesting phenomenon. Under the surplus carbonate ion of the environment, the Cu2O cubes show the impairment on the corner. Base on the aging experiment and the base source replacement, we demonstrate that impairment is caused by the adsorption of carbonate ion on (111) plane. In the part two, we discuss the influence on crystal growth of the different chelating agent. The citrate ion stabilize the (100) plane and the (111) plane, but the (100) plane is more thermodynamically stable. EDTA is a strong agent to ensure the Cu2O crystal to be cube shape even on the edge and the corner. And the tartrate ion is with high stability of (111) to Cu2O. The crystal growth mechanism with different chelating agent is figured out too. In the part three, the surfactant is introduced. When the functional group is with oxygen atom such as S-O bond, C-O-C bond and C-O bond, it’s hard to produce the Cu2O with preferred orientation. The oxygen base functional group would increase the (100) plane stability only on the extremely high concentration. The quaternary alkylammonium salt is powerful to accelerate the growth rate in <111> direction, but the primary alkylammonium salt shows no use. When the long carbon chain is more complex, the growth rate in <111> direction is faster.Generally, this dissertation is useful in understanding the grow mechanism of Cu2O crystal. Based on the conclusion, Cu2O exhibits higher application potential in the semiconductor industry in the future.