Controllable Synthesis And Properties Large-Scale, Well-uniform Cu_2-x Se Nanoarrays

As important p-type semiconductors, non-stoichiometric Cu2-xSe have great potential applications in thermoelectronics,optoelectronics, catalysis, sensing, superconductors and solar cells. Preparation of semiconductor nanoarrays with well-defined size, morphology, dimensionality and diversity through novel synthesis approaches and investigations of their formation mechanism should be a key precondition to reveal the relations between the structure and propertie, assemble the nanocrystals into superstructures and pave the way to the real applications. In this dissertation, valuable explorations have been carried out on new solution-based manipulated synthetic strategies for large scale and well uniform Cu2-xSe nanostructures'arrays on the copper substrate along with their formation mechanisms and novel properties, emphasizing on the relationship between crystal symmetry and morphology manipulation as well as the connection between properties and size/morphology of nanomaterials.Large scale and well-aligned arrays made of the Cu2-xSe nanosheets on the copper substrate have been fabricated by a simple hydrothermal route without using templates and catalysts. The crystal structure and general morphology of the products are first characterized by XRD analysis, SEM and TEM observation, respectively. A large amount of high ordered potato chips shaped Cu2-xSe nanosheet array with thickness of 30-50 nm are densely packed and uniformly covered over the entire surface of the Cu substrate. Control experiments with the different of the concentration of NaOH, temperature are also carried out. The experiment results are demonstrated as follows:With the reaction temperature increasing, the morphology of Cu2-xSe nanomaterials will change. The formation mechanism is investigated in details and believed to be closely related to their layered structure. Here, we have, indeed, been able to organize Cu2-xSe nanostructure arrays on prescribed arbitrary patterns with unprecedented control and selectivity. The present micropatterned assembly route is envisaged to be highly useful for the fabrication of novel patterns on other metal substrates to meet the growing demands of micro-and nanoscale patterning techniques.In our experiments, the morphology of the Cu2-xSe products is found to be dependent strongly on other reaction conditions such as reaction solution systems, the selenium resource, add ammonia. Also, the nucleation and growth process of Cu2-xSe have been adjusted, and a series of different morphology of large scale Cu2-xSe nanostructures'arrays are obtained. In the proeess of study on produet morphology, it is comfinned that this reaetion obeyed polar growth meehanism of crystal under alkalescent condition. The PL spectra from the different Cu2-xSe nanoarrays show that the stronger the intensity of the PL spectra, the bigger is the diameter of primary rod in secondary rod bundles. The wettability properties of the Cu2-xSe nanostructures have been investigated, and the water contact angle from these nanostructured materials has been measured to be up to 160°, showing a superhydrophobicity. The investigation on the wettability of the Cu2-xSe nanostructures films shows that the angle of contact (CA) is mostly relied on the surface shape, and the CA of the Cu2-xSe nanostructures films varying with their surface shape. Therefore, the wettability of solid substrates can be well-controlled through the cooperation of various Cu2-xSe nanostructured surfaces and the chemical modification.At last, based on published article and experimental facts, valuable explorations have been carried out on new synthetic strategies of ZnSe/Cu2-xSe and Ag2Se/Cu2-xSe heterojunction nanomaterials. One-dimensional ZnS nanowires were synthesized by hydrothermal method which provided a new viewpoint for the formation of ZnSe/Cu2-xSe heterojunction.