Controlled Synthesis Of Cu₂O Micro-Nanomaterials In Imidazolium Ionic Liquids

As a type of green media, ionic liquids (ILs) have the advantages of negligible vapor pressure, non-flammability, low surface tension, good thermal stability, high solubility power, wide liquidus range, etc. Ionic liquids are environmentally benign solvents for replacement of traditional volatile organic solvents in organic synthesis, extraction, catalysis, micro-nanomaterials synthesis and other fields. In rencent years, many studies have reported the ionic liquids as a stabilizer using in the one-dimensional nanomaterials synthesis, three-dimensional petals, nanoparticles, nano-hollow ball. As for the research about the formation of aggregation and micelles for ionic liquids in aqueous solution, which proved to us the ionic liquids can play the same role as surfactant in the synthesis of materials. However, there are few reports about the effect of ionic liquids on Cu₂O micro-nanocrystals.In this work, we report a solution reduction method for the preparation of controllable morphology of Cu₂O microcrystals with ILs-assisted. The method is easy to operate, and it is not easy to introduce impurities in the closed state. The control model of ILs in the solution synthesis of Cu₂O was obtained by analyzing the effects in the process of synthesis. It is hoped that this can provide some theory supports to the molecular design and extending application of ILs.As a part of the project supported by the National Natural Science Foundation of China (No. 20873036)), the maincontents of the thesis are summarized as followed:(1) According to the synthetic methods reported in the literature, the synthesis and purification of ionic liquids of [C₈mim]X (X = Cl^–, Br–, PF6–), [C_nmim][BF₄] (n = 4, 6, 8), [MIMCH₂COOR]Cl (R = -CH₃, -CH₂CH₃, -CH₂CH₂CH₃, -(CH₂)2CH₃) were conducted.(2) Solvothermal method was demonstrated for the synthesis of controllable morphology of Cu₂O micro-nanoflowers under the control of ionic liquids, ethylene glycol as the reducing agent. The effects of reaction temperature, reaction time, reactant concentration and amount of ionic liquid on the synthesis of Cu₂O crystal were studied, and the synthesis methods of Cu₂O micro-nanopetals were obtained under optimum conditions. Micro-nano-petals crystalline were studied by the adsorption and photocatalytic degradation of methylene blue. (3) Solvothermal method was successfully used to synthesis Cu₂O micro-nanocrystals using ethylene glycol as a reducing agent under the control of [C₈mim]X (X = Cl^–, Br^–, PF₆^–), [C_nmim][BF4] (n = 4, 6, 8), [MIMCH₂COOR]Cl (R = -CH₃, -CH₂CH₃, -CH₂CH₂CH₃, -(CH₂)2CH₃). The effect of alkyl chain length of cation and anion types on the morphology and size of products were investigated, on the basis of which the mechanism of synthesis of Cu₂O in ionic liquids were proposed.(4) Low temperature liquid phase method was reported to synthesis well dispersed micro-nanocauliflower of Cu₂O with small and uniform size, using glucose as reducing agent.The effect of anions and the alkyl chain length for ionic liquid on crystallization of product were studied. It was proposed that the key effects of controlling the morphology of the crystals were the anion of ionic liquids.