Nickel and nickel oxide nanocrystals selectively grafting on multiwalled carbon nanotubes

Abstract

Nickel and nickel oxide nanocrystals in their pure phase are carefully embellished by a facial method on oxygen-functionalized multi-walled carbon nanotubes (O-MWCNTs) using nickel nitrate (NN) was effectively accomplished for the first time by calcining them in hydrogen, nitrogen and air, respectively, at suitable temperatures. Nickel and nickel oxide nanocrystals impregnated O-MWCNTs were examined for its structure and morphology by various techniques, such as powder X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and field emission scanning electron microscopy. The nanocrystals on the O-MWCNTs were determined of 15-20 nm size. Decorated nanocrystals on CNT's have potential applications in semiconductor industries.Keywords: MWCNTs; Nickel Nitrate; TEM; XRD; FTIR BackgroundIn the field of nanoscience and nanotechnology carbon nanotubes (CNTs) are the most wanted materials due to their extraordinary properties and potential applications as step forward materials for catalysis, composite reinforcement materials, microelectronics, energy storage, chemical sensors, etc. [1,2]. Mechanical stiffness, field emission properties, excellent thermal and electrical conductivity, high aspect ratio, and the cavities of CNTs fetches them the advantage in their applications [3][4][5][6]. CNTs are chemically inert and insoluble in the most solvents thus hampering their application and manipulation in various possible fields. Surface functionalization of CNTs is one way of overcoming these difficulties. This method has established a wide range of applications in the fields of composite materials, sensors and catalysis [7][8][9][10].By the application of oxidation reagents like HNO 3 or a mixture of H 2 SO 4 /HNO 3 can disjoint the aromatic ring system of CNTs [11]. As a result carboxylic (−COOH), carbonyl (−CO) and hydroxylic (−OH) can be present on the nanotubes as they are required to anchor guest species such as metal ions to the CNT [12,13]. The wetting characteristics and reactivity of nanotubes are modified thus enriching their properties. It guides us to the subject of interfacial bonding between the metal atoms and defective and oxidized CNTs to ensure excellent mechanical performances for the CNT-reinforced metal-matrix composites.The stable CNT-metal structures are potential engineering materials in the areas of CNT devices for different spintronics applications and CNT metal-matrix composites [14][15][16]. In much energy related applications like fuel cells, super capacitors, rechargeable batteries and hydrogen production Ni/CNT nanocomposites have been considered [17][18][19]. Production of metal/metal oxide and CNT composites were attempted by many but no uniform coating of CNTs were obtained. However some worked with polymers to assist the process of decorating of metal/metal oxides [20,21]. For example, Tang et al. [20] reported that Ni decorated MWCNTs were modified with poly (acrylic acid) for hydrogenation of α, β-unsaturated aldehyde. Similarly homogeneous e...