The synthesis of nickel nanoparticles with controlled morphology and SiO2/Ni core-shell structures

Abstract

The magnetic nanopowders can be potentially applied in wide range of fields such as magnetic storage, magnetic fluid, medical diagnosis, conducting paints, rechargeable batteries, optoelectronics, magnetic recording media, drug delivery system and catalysis. They have attracted interest in the past decade and have also been studied extensively because of their size-and shape-dependent physical-chemical and magnetic properties for applications in various useful technologies. In this work, we present our experimental results on the preparation of nanosized Ni nanoparticles with different shapes by using a wet chemical solution route. Ni nanoparticles were prepared by reducing a Ni-complex formed between nickel-acetate and hydrazine solution under basic condition. Then through the control of reaction temperature and ageing time, nanosized Ni particles with different morphologies could be formed. The morphology and sizes of synthesised nanostructures were studied by scanning electron microscopy (SEM). Structural properties of nanoparticles were examined by X-ray diffraction. We also report the coreshell structures of micro-composites of silica-nickel (SiO 2 /Ni). The composite core-shell structures were formed by the control of the surface charges of particles in aqueous solutions. A specific composite (SiO 2 /Ni) can be produced by controlling the surface charge, the pH and the molar ratio of the components. Core-shell structures are stable at room temperature.

Enzyme biosensor based on the immobilization of HRP on SiO2/BSA/Au composite nanoparticles

“…Nanoparticles have often been used in constructing electrochemical biosensors due to their special features including their large surface area, high surface free energy, and good biocompatibility [12,13]. For example, metal nanoparticles can be used to promote electron transfer between proteins and electrodes.…”

“…For example, metal nanoparticles can be used to promote electron transfer between proteins and electrodes. Particularly, Au nanoparticles (nano-Au) have been extensively used as an immobilized matrix to promote the direct electron transfer of the immobilized redox proteins [10][11][12][13][14][15][16]. Xiao et al developed a biosensor based on HRP immobilized on nano-Au.…”

Electroless nickel metallization to prepare SiO2–Ni composite particles via polyelectrolytes route

“…The polyelectrolytesmodified PS beads bearing a negative surface charge were able to attract positively charged, 4-dimethylaminopyridine-coated Au nanoparticles in chemical solutions. Similar electrostatic approach has been used to prepare SiO 2 -Ni composite particles [26,27]. These findings shed lights on using the electrostatic LbL assembly to form metallic nuclei on surface of SiO 2 core preferentially so that the nucleated sites may grow into a continuous metal deposition via the electroless plating.…”

“…Routes to synthesize the composite particles with tailored hierarchical structures include, for example, preferential surface precipitation, seeded growth, Pickering emulsion, electroless (autocatalytic) plating, sonochemistry, and electrostatic layer-by-layer (LbL) assembly [9,10,[13][14][15][16][17][18][19]. Among them, the electroless plating involves use of chemical reducing agent to facilitate reduction of metallic ions in solution so that metallic nuclei can deposit preferentially on the core surface of various chemical compositions, forming either a uniform metal shell or a raspberry core-shell structure so long as a continuous electron transfer between the reacting species can occur selectively at specific activation sites on the core surface [3,9,10,[20][21][22][23][24][25][26][27][28][29][30][31]. The process is facile with a good throwing power, and is also flexible and cost-effective.…”

Preparation and growth mechanism of nickel nanowires under applied magnetic field

“…In addition, much attention has been focused on one-dimensional (1-D) nanostructure such as nanorods, nanowires, nanofibers and nanochains due to their potential applications in nanodevices [3][4][5]. As a typical magnetic material, 1-D metallic Ni nanomaterial in uniform morphology and high purity has become increasingly mandatory for specific applications such as microwave absorbing materials, magnetic recording media, gas sensors, drug deliveries, commercial batteries and catalysts [6][7][8][9][10][11][12]. To date, much effort has been made to prepare Ni nanomaterial with 1-D structure.…”