Controlled Synthesis And Catalytic Performance Of Cuprous Oxide Based Micro/nano Materials

As a promising material with special bandgap structure,chemical and electrical properties,Cu₂O crystals have attracted increasing attention due to their potential application in the field of catalysis,photovoltaics and gas-sensing.This thesis focuses on the synthesis and application of Cu₂O.A series of Cu₂O crystals with different structures have been synthesized by the liquid-chemistry method.The catalytic performance of Cu₂O in ammonium perchlorate（AP）thermal decomposition and visible light photolysis of organic pollutants has been systematically investigated.The content of this thesis is listed as follows:1.Cu₂O micro-crystals with five different strutrues have been synthesized through hydrothermal method.The effect of ligand dosage and reaction temperature on the products has been investigated.By adjusting the dosage of ligand,the structural evolution of Cu₂O micro-crystals evolved from cube to octahedron,then to other three types of branching structures（including 12-pods,8-pods and hexapod structure）.Cu₂O microcrystals with five different strutrues have been used as catalysts to promote the thermal decomposition of AP.Finds indicated that Cu₂O microcrystals could decrease the low and high decomposition temperatures of AP,and increase the decomposition heat,significantly.The preferable catalytic performance of Cu₂O cubes in the thermal decomposition of AP has been established by AKTS thermo-dynamic software.2.Evolution of Cu₂O structure,from a cubic aggregate to a mono-dispersed cube,then to a {100} planes etched cube,has been presented in the microwave-assisted system.The effect of solvent composition and microwave irradiation on the structure of products has been investigated.The mechanism of structural evolution of Cu₂O cubes has been studied by investigating the solvent effect in the system.Catalytic activity of three typical kinds of Cu₂O cubes in the thermal decomposition of AP has been investigated.Finds indicated that Cu₂O cubes decreased the low and high decomposition temperatures of AP,and increased the decomposition heat,obviously.AKTS thermo-dynamic software has been used to invesitigate the catalytic decomposition process of AP after loading Cu₂O cubes.Cu₂O cubic aggregates and mono-dispersed cubes have preferable catalytic activities in triggering the decomposition of AP,whereas the activation energy of AP decomposition catalyzed by{100} planes etched Cu₂O cube maintains at a low level in the high temperature decomposition process.Kinetic parameters obtained from the dynamic calculation have been used to predict the reaction rate and progress of AP with Cu₂O cubes under some certain conditions.3.A facile method with assistance of ultrasonic technique has been developed to synthesize Cu₂O and Cu₂O-Cu micro-spheres with different structures.By prolonging ultrasonic irradiation time,the solid spheres of Cu₂O transformed into core-shell structure,then into hollow spheres,which accompanied with composition shift.The reactional conditions on the effect of spheric formation and evolution have been systematically investigated to present the evolutional machenism which is based on the disproportionate reaction and re-crystallization of Cu₂O.Furthermore,the catalytic comparation of the spheres in the visble light photolysis of methyl orange（MO）have been carried out.Cu₂O-Cu hollow spheres with a shell thickness about 30 nm exhibited excellent adsorption ability and better photo-catalytic activity for the degradation of methyl orange compared to other structures.4.A vesicle templating approach has been developed to synthesize the low-density Cu₂O spheres with patterning surface.AOT/SDBS vesicles with high uniformity and stability have been established and used as templates in the synthesis of Cu₂O.Cu₂O spheres are centripetally assembled by a plenty of nanoplates whose thickness can be kinetically adjusted by controlling the dropping speed of the reducer solution.A vesicle templating mechanism for the in situ crystallization of Cu₂O has been proposed by monitoring the formation process of low-density Cu₂O spheres.After formation of the stable AOT/SDBS vesicles in aqueous solution,Cu-pyridine complexes adsorb on the surface of the AOT/SDBS vesicles through the electrostatic interaction.Then,a rapid reduction reaction of Cu₂O nanoplates initially occurs on the surface of the vesicles to form hollow structures,which can solidify the spherical structures.Finally,the perpendicular growth of Cu₂O nanoplates penetrates the bilayer membrane of the vesicles to form the low-density spheres.Cu₂O spheres have been applied into the visible light photolysis of organic pollutants.Compared to TiO2 powder and Cu₂O solid spheres,the low-density Cu₂O spheres demonstrated the preferable adsorption capacity for MO,and can effectively catalyzed the photo-degradation of MO.