Low Temperature Solution-synthesis And Properties Study Of Copper And Copper Oxide Nanomaterials

In this paper, the copper and copper oxide nanomaterials were synthesized at lowtemperature in aqueous solution. Reaction mechanism and properties characterizationswere also conducted. Investigations are based on several aspects including synthesis,mechanism, properties and applications. The content mainly involve preparation,reaction mechanism and properties study of CuO nanoleaves, Cu flowers, Cuoctahedral cages, Ni-catalyzed Cu nanocrystals, multi-rods Cu₂O crystals andSiO₂-protected Cu nanoparticles.Firstly, CuO nanoleaves were successfully synthesized from Cu(OH)₂precipitation at room temperature in aqueous solution. According to thetransformation mechanism, Cu(OH)₂→Cu(OH)₄^2–→CuO, amounts orconcentrations of NaOH in the system plays an important role in controlling thereaction velocity. Transformation can be accomplished in15³0min by adjustingNaOH solution in a appropriate amount and concentration. Morphologies anddispersibility of samples were improved by introducing surfactants into the system.The obtained CuO nanoleaves were stably suspended in ethanol.Then, CuO nanoleaves synthesized at room temperature were reduced to Cunanostructures by adding reducing agent into the system. Cu nanocrystals withdifferent structures were obtained by adjusting the reducing agent quantity andreduction time. When the reducing reaction took place fast, CuO nanoleaves werereduced to Cu₂O and then to Cu nanoparticles. Cu particles aggregated togetherforming Cu spheres, and Cu flowers were finally obtained with further growth.Accurate controlling the reducing agent quantity and reduction time, Cu octahedralcages were obtained through the morphology heredity from Cu₂O octahedra.TG–DTA analysis illuminated that Cu octahedral cages had higher stability than Cuflowers. The as-prepared Cu nanostructures were used to construct non-enzymaticglucose sensor, which has a well-defined, stable and fast amperometric response.We also studied the behavior of oleic sodium (SOA) in preparation of CuO nanoleaces at room temperature. It was found that adding SOA could not only slowdown the transformation velocity from Cu(OH)₂to CuO, but also effect themorphology of CuO nanoleaves. When the amount of OA–is sufficient in the system,top of the CuO nanoleaf would be branched and separated into nanorod finally. Theinhibited effect of SOA also existed when reducing the SOA-decorated CuOnanoleaves to Cu nanocrystals. By introducing Ni²⁺into the system, reducing reactionwas catalyzed and could accomplish in a short time. TG–DTA results implied that theNi-assisted Cu octahedral cages had higher stability than Cu octahedral cages withoutNi.Otherwise, reducing behavior of NaH2PO₂was studied under different conditions.Multi-rods Cu₂O crystals were obtained from Cu(OH)₄^2–under alkaline condition.Increasing the concentration of CuSO₄, morphologies of Cu₂O crystals change asoctahedron, divided octahedron, six-rods and arrow. According to the bond-valencestructure transformation of NaH₂PO₂in acidic condition, Cu nanoparticles weresuccessfully synthesized by adjusting the solution pH to5⁶. SiO₂were introducedto protect the Cu nanoparticles from oxidation. TG–DTA characteration informed thatas the SiO₂content increased, the stability of Cu nanopaticles was improved.Moreover, introducing SiO₂could also improve the morphologies and dispersibility ofCu nanoparticles.Finally, the as-prepared CuO nanoleaves, Cu nanoparticles and multi-rods Cu₂Ocrystals were used as catalysts for the thermal decomposition of AP. The hightemperature of AP decomposition decreased from472.7oC to308oC when CuO1%was used, and the unit enthalpy of AP decomposition increased. Moreover, CuOnanoleaves were recyclable for AP decomposition. Thank to its higher catalyticactivity, nano-Cu showed good catalytic effect for AP decomposition. The maindecomposition temperature of AP was decreased to319oC when nano-Cu2%wasused. The unit enthalpy was improved to79.07J g^–1s^–1, which is about3.9times ofpure AP. Fast heat release of AP decomposition with high exothermic is realized atlow temperature under Cu nanoparticles' catalysis.In summary, our research invoved the synthesis, characteration ang propertiesstudy of copper and copper oxide nanomaterials. The preparation method is facil andsimple, the as-prepared samples have widely use in non-enzymatic glucose sensor anddecomposition of AP.