Preparation Of Colloidal Chalcogenide Nanomaterials And Heteronanostructures And Their Properties Investigation

Colloidal nanocrystals referred to as’artificial atoms’have been intensively developed during the past decades for being grown from many different materials and cheaply produced in fairly large amounts with uniform size and shape. As one particular interesting emerging class of colloidal nanostructures, heterostructured nanocrystals containing two or more chemically distinct components, i.e., semiconductor-semiconductor or semiconductor-metal, in one single nanostructure with multifunctional or new properties induced by the heterointerfaces will undoubtedly lead to revolutionary new applications of nanomaterials in various fields, such as photovoltaic devices, high-performance catalysis, biological and biomedical sensing, and a new generation of optoelectronic devices. Herein, we report solution-process for controlled synthesis of several chalcogenide nanomaterials and heterostructures. The detail can be summarized as follows:1. We present a new colloidal route for the synthesis of hexagonal prism Cui94S-ZnS, Cu1.94S-ZnS-Cu1.94S and Cu1.94S-ZnS-Cu1.94S-ZnS-Cu1.94S heteronanostructures with screw-, dumbbell-, and sandwich-like shapes by using CuI and Zn(S2CNEt2)2as precursors in oleylamine. This colloid method may provide a new way for controlled growth of a family of metal chalcogenide heteronanostructures with interesting optical property or multifunctionalities for applications in optoelectronic devices, such as solar cells, and optical sensing. Using the similar method, we synthesized dumbbell like Cu2S-CuS heteronanostructures with Mn2+assistant. Under the influence of Mn2+, we find that the Cu2S nanocrystals can completely transform into CuS nanoplates finally.2. Unique colloidal AgFeS2ternary nanocrystals can be synthesized at150℃for the first time in oleylamine solution. Interestingly, such ternary AgFeS2nanocrystals can further transform to Ag2S-Fe7Sg heterodimers by internal thermal reaction, which can be extended to synthesize other family of semiconductor heteronanostructures. These ternary AgFeS2nanocrystals with a band gap of1.21eV and their transformed Ag2S-Fe7S8heterodimers with different magnetic and optical property, which may have potential applications in photovoltaic devices as a promising light-absorbing material.3. We report a facile bottom-up approach to prepare Cu2S1-xSex hexagonal nanoplates by a colloidal solution reaction in1-octadecene using CuCl, S and SeO2as precursors. Because of the high chemical stability of SeO2and its facile dissolution in1-octadecene at low temperature, this new synthetic approach does not require the use of a glove box. Furthermore, Cu2S1-xSex nanoplates can be sequentially converted to CdS1-xSex, and ZnS1-xSex nanocrystals by use of exchange reactions. It has been found that Cu2S1-xSex (x≠1) nanocrystals favor to form hexagonal structure, while Cu2Se nanocrystals favor to form cubic structure under the same experiment conditions. This approach provides a new route to access a family of other alloyed semiconducting nanocrystals.4. We develop a new route for the synthesis of metals and metal-sulfides heterostructures with multiple sulfides as the precursors. Using the solution process, we find that triphenylphosphine can extract the Ag+and Bi3+from the nanostructural chalcogenides and reduce them to the zero-valent state for the first time. Using this reaction principle, we successively synthesized Ag, Bi, Ag-NiS, Ag-ZnS, Ag-InS, Ag-FeS, Ag-Bi, Bi-Cu2S nanostrucyures.