Preparation And Properties Of Noble Metal Nanocomposites Based On MnOOH And Ni?OH?₂

Manganese, nickel oxides/hydroxides nanomaterials have attracted significant attention owing to their high surface and excellent catalytic properties in recent years. MnOOH is an important precursor for other manganese oxides. Due to its good electrochemical, catalytic and physical properties, MnOOH has been often used as electrocatalyst,adsorbent, molecular sieve, and so on. 1D MnOOH nanowire is also an excellent support for preparation of nanocomposites because of its high surface area and rich hydroxyl radicals. 3D Ni(OH)2 has unique superstructure and can be used as supercapacitors, gas sensors, catalysts etc. In this thesis, several noble metal nanocomposites were successfully prepared by using 1D MnOOH nanowires and 3D Ni(OH)2 nanoflowers as the support. The catalytic performance of as-obtained products for reduction of aromatic nitro compounds and their electrochemical property were investigated. The main contents are given as follows:(1) 1D MnOOH nanowires were firstly synthesized with a hydrothermal method. Then, MnOOH/Au nanocomposites were prepared using 3-aminopropyltriethoxysilane(APTES) as the organic modifier and HCHO as the reducing agent. The as-obtained nanocomposite was characterized by scanning electron microscopy(SEM), powder X-ray diffraction(XRD), high resolution transmission electron microscopy(TEM/HRTEM), and X-ray photoelectron spectroscopy(XPS). The catalytic performance of the nanocomposite for reduction of aromatic nitro compounds was investigated. Our results showed that the as-synthesized MnOOH/Au composites exhibited excellent catalytic performance for the reduction of aromatic nitro compounds(2) 1D MnOOH nanowires were firstly synthesized by a hydrothermal method. Then we used poly(sodium-p-styrenesulfonate)(PSS) as a capping agent to connect Ag+ and MnOOH through electrostatic attraction. A novel 1D MnOOH/Ag-nanoplatesnanocomposite was two-step successfully synthesized through an in-situ growth of Ag on the surface of MnOOH nanorods, with HCHO as the reducing agent and polyvinyl pyrrolidone(PVP) as the surfactant and stabilizer. The as-obtained products were characterized by SEM, XRD and HR(TEM). The catalytic performance of the product for the reduction of 4-nitrophenol was investigated. The results showed that the MnOOH/Ag heterostructures could be used as the excellent catalyst for the reduction of 4-nitrophenol.(3) 3D Ni(OH)2 nanoflowers were synthesized by a hydrothermal method firstly. Then Ni(OH)2/Ag nanocomposites were one-step prepared with a simple solvothermal method using N,N-Dimethylformamide(DMF)as the solvent and Ni(OH)2 nanoflowers as the support. The as-obtained products were characterized using SEM, XRD and HR(TEM). The catalytic performance of the nanocomposite for reduction of4-nitrophenol and its electrochemical property were investigated. It was found that the prepared Ni(OH)2/Ag nanocomposites exhibited excellent catalytic performance for the reduction of 4-nitrophenol. In addition, the product has potential supercapacitor performance.