Controllable Preparation And Properties Of Copper Oxide Single Crystals And Composites

Simple copper oxides,represented by CuO and Cu₂O,have various applications in various fields.The preparation and corresponding properties of these two simple oxides have long been the focus of inorganic solid-state chemistry.In this paper,we started with the controllable synthesis of simple copper oxides.Based on an in-depth understanding of the behavior of copper ions under alkaline conditions,we prepared centimeter-sized CuO plate crystals,nanoscale CuO lamellar and double-walled Cu₂O nanospheres using three surfactants.Furthermore,we combined them with two other oxides obtaining three different kinds of interfaces and improving the corresponding catalytic performance of the composites.1.In this paper,CuO-plate crystals with a size of centimeters are first prepared under highly alkaline hydrothermal conditions.The crystals have a black metallic luster,a smooth surface without cracks,an area of up to cm²,and a uniform thickness about 20?m.The reason for the formation of an oversized layer is that trivalent chromium with a planar structure is formed by a trivalent chromium ion under conditions of an ultra-high alkalinity,and at the same time,Cu²⁺as a raw material for the reaction also forms a plane-structured intermediates under alkaline conditions—Cu?OH?₄^2-.There are inter-layer hydrogen bonding interactions between the reaction intermediates of the two planar structures,thus limiting the growth of Cu?OH?₄^2-intermediate along the c-axis,making Cu²⁺ions can only be attached to the CuO seed crystal from the a-axis and the b-axis.In addition,we also studied the experimental parameters of the hydrothermal reaction process,including the reaction temperature,reaction time,the amount of Cr³⁺ions and other factors affect the product species,and obtained the optimal synthesis conditions for CuO wafers.2.With an in-depth understanding of the behavior of Cu²⁺ions in alkaline solutions,we prepared Cu₂O double-walled nanospheres in NaOH alkaline solution using CTAB as the template.Using a two-step method,the outer wall of this double-walled nanosphere is uniformed coated with a layer of CeO₂ nanoparticles to form Cu₂O@CeO₂ core-shell nanospheres.The water oxidation reaction performance of the nanospheres was tested.It was found that compared with pure phase Cu₂O,the water oxidation activity of the composite material was significantly improved,indicating that there is a certain synergy between Cu₂O and CeO₂.We also used the same synthetic method to prepare a composite material of CuO nanosheets and CeO₂ nanoparticles without addition of ascorbic acid reducing agent,Changed the input of Cu²⁺and Ce³⁺molar ratio,the effect of the structure and morphology of the composites on the oxygen production performance of the OER electrochemical catalysis was investigated.It was found that after the loading of CeO₂ nanoparticles,the OER starting potential of the composite material became lower,indicating that there is also a synergetic relationship between CuO and CeO₂.3.Finally,we used TBAOH as a surfactant and provided an alkaline environmentto the reaction.CuO nanosheets were prepared at room temperature.At the same time,a layered perovskite niobate[Sr₂Nb₃O₁₀]^-nanosheet with well dispersity was prepared by combining high temperature solid phase with liquid phase delamination.The resulting CuO nanosheet was composited with[Sr₂Nb₃O₁₀]^-nanosheet.After being calcined and annealed,the CuO nanosheets collapsed into particles,forming a heterogeneous interface between the agglomerated particles and the nanosheet.The electrochemical catalytic properties of the OER were investigated,too.The characterization shows that the starting potential of the composite material is reduced,indicating that there is a certain synergy between CuO and[Sr₂Nb₃O₁₀]^-.In this paper,in order to master the behavior of transition metal ions such as Cu²⁺and Cr³⁺in alkaline solution,we first prepared a centimeter-sized CuO plate in a highly alkaline hydrothermal environment.Secondly,Cu₂O double-walled nanospheres and CuO nanosheets were prepared by means of surfactants such as CTAB and TBAOH,respectively.Thirdly,Cu₂O double-walled nanospheres and CuO nanosheets were composited with CeO₂ nanoparticles and[Sr₂Nb₃O₁₀]^-nanosheets to obtain three kinds of different interfaces(Cu₂O@CeO₂ core-shell nanospheres,CuO nanosheets and CeO₂ nanoparticles,CuO particles and[Sr₂Nb₃O₁₀]^-nanosheets,etc.)explored the synthetic conditions required for the construction of different interfaces,as well as their synergetic relationship.