Preparation,Characterization And Properties Of Rod-Like CuO And Hollow Copper Selenide Nanomaterials

CuO and copper selenides have been extensively studied because of their versatile applications,such as catalysts,superconductors,magnetic storage media,gas sensors etc.In this thesis,rod-like CuO,hollow copper selenide nanospheres and copper selenide nanowires were synthesized by precipitation combining with heat conversion method,sacrificial template method and microwave assisted method,respectively.The morphologies,crystal structures and properties of the as-synthesized samples were studied by SEM,TEM,XRD,UV-Vis diffuse reflectance absorption spetra,PL spectra and electrochemical measurements.The effects of various reaction conditions on the product morphologies were studied and formation mechanism was proposed.The main content of this thesis includes:1.Hierarchical rod-like CuO was synthesized by precipitation combining with thermal decomposition method using CuSO4,KOH,polyacrylamide?PAM?as a directing agent.The morphology,crystal structure,optical properties,gas sensing property and elecetrochemical sensing properties of the sample were investigated by XRD,SEM,TEM,PL spetra,UV-Vis absorption spectra and ectrochemical measurements.The influencing factors to product morphologies were investigated on the basis of series of control experiments and the formation mechanism of the quasi rod-like CuO was proposed.The results clearly show that the hierarchical rod-like CuO has strong light-harvesting capacity in both ultraviolet and visible light region and its gas sensing property was greatly enhanced in ammonia,4.3 times higher than that in air.The electrochemical results display that the CuO modified electrode has fast amperometric response to glucose,high sensitivity and low detecting limit.The other rod-like CuO with nanowire hierarchical structure has been synthesized successfully by a facile ultrasound method using Cu?NO3?2,KOH,NaOH,polyacrylamide?PAM?as a directing agent.The samples were characterized by XRD,SEM,TEM,PL and UV-Vis absorption spectra.The results clearly show that each CuO rod?200-300 nm in diameter?is assembled by tens of parallel nanowires and each nanowire consists of numerous interconnected nanoparticles with sizes of about 15 nm.It has strong light-harvesting capacity in UV-visible light region with band gap energy of 1.56 eV.The cavitation effect induced by ultrasound could be beneficial to oriented self-assembly of the Cu?OH?2 nanowires.The series of control experiments show that ultrasound processing and existence of NO3-ions play key roles on formation of the hierarchical CuO rods.2.Cu3Se2 nanospheres with smooth and rough surfaces were successfully synthesized by a sacricial template method using CuCl2,Se,Na2SO3 and NaOH as raw materials.The morphology,crystal structure and optical properties of the samples were studied by SEM,XRD and UV-Vis absorption spectra.The results show that reaction temperature and Se2-concentration play key roles on formation of the hollow structure.Cu3Se2 hollow nanosphereswere formed via the Kirkendall effect.SEM and XRD results show that the diameter of the hollow Cu3Se2 nanosphere is larger than the Cu2 O template and the samples are not pure phase of copper selenides,but contain the unreacted Cu2 O precursors.The UV-Vis spectra display that the two samples have different light absorption properties in the range of 400-800 nm.3.Cu₂Se nanowires have been successfully synthesized by a facile template-free solution route using a Se2-solution prepared by microwave-assisted method.The morphology,crystal structure and optical properties of the sample were studied by XRD,SEM,TEM,PL and UV-Vis absorption spectra.The results show that Cu₂Se nanowire has diameter of about25 nm and length of several hundred nm.The direct band gap energy of the Cu₂Se nanowires is 2.02 eV,consistent with the values reported earlier.Its PL spectrum shows obvious broad emission band from 370-600 nm.It mainly emits blue light.