Facile morphology-controlled synthesis of nickel-coated graphite core–shell particles for excellent conducting performance of polymer-matrix composites and enhanced catalytic reduction of 4-nitrophenol

Abstract

We have developed a novel seed-mediated growth method to fabricate nickel-coated graphite composite particles (GP@Ni-CPs) with controllable shell morphology by simply adjusting the concentration of sodium hydroxide ([NaOH]). The fabrication of two kinds of typical GP@Ni-CPs includes adsorption of Ni via electrostatic attraction, sufficient heterogeneous nucleation of Ni atoms by an in situ reduction, and shell-controlled growth by regulating the kinetics of electroless Ni plating in turn. High [NaOH] results in fast kinetics of electroless plating, which causes heterogeneous nuclei to grow isotropically. After fast and uniform growth of Ni nuclei, GP@Ni-CPs with dense shells can be achieved. The first typical GP@Ni-CPs exhibit denser shells, smaller diameters and higher conductivities than the available commercial ones, indicating their important applications in the conducting of polymer-matrix composites. On the other hand, low [NaOH] favors slow kinetics. Thus, the reduction rate of Ni slows down to a relatively low level so that electroless plating is dominated thermodynamically instead of kinetically, leading to an anisotropic crystalline growth of nuclei and finally to the formation of GP@Ni-CPs with nanoneedle-like shells. The second typical samples can effectively catalyze the reduction of p-nitrophenol into p-aminophenol with NaBH in comparison with commercial GP@Ni-CPs and RANEY Ni, owing to the strong charge accumulation effect of needle-like Ni shells. This work proposes a model system for fundamental investigations and has important applications in the fields of electronic interconnection and catalysis.

Electroless Plating of Graphene Aerogel Fibers for Electrothermal and Electromagnetic Applications

“…In the reaction, NaOH played an important role in the growth rate of nickel nanoparticles. Generally, the higher the concentration of NaOH, the faster the growth of nickel nanoparticles according to the previous research. − It is found that the optimum concentration of NaOH was 0.75 M. Besides, temperature was another important factor of the electroless plating reaction. The reaction rate was very slow when the temperature was lower than 90 °C.…”

“…In the pretreatment process, the graphene hydrogel fibers with negative charges due to the incomplete reduction intended to absorb sufficient Ni 2+ ions through electrostatic adsorption from the nickel sulfate solution, and the absorbed Ni 2+ ions were in situ reduced by NaBH 4 on the graphene sheets to form nickel nuclei. In the electroless plating process, the above nickel nuclei could act as autocatalytic active centers to induce the growth of nickel nanoparticles . N 2 H 4 ·H 2 O was the dominant reducing agent in the plating solution, and the reaction mechanism was shown in the following equation. …”

“…In the electroless plating process, the above nickel nuclei could act as autocatalytic active centers to induce the growth of nickel nanoparticles. 24 N 2 H 4 •H 2 O was the dominant reducing agent in the plating solution, and the reaction mechanism was shown in the following equation.…”

Low density magnetic silicate-nickel alloy composite hollow structures: seed induced direct assembly fabrication and catalytic properties

“…More seriously, the inherent ferromagnetism of FTM NPs brings additional magnetic dipole interaction that favors the aggregation. 10 According to the previous reports, the deposition of FTM NPs or noble metal NPs onto various supports, such as graphene, [14][15][16][17] oxides, [18][19][20] and mesoporous silica, 21,22 or composite substrate 23,24 have been extensively explored to achieve better dispersion, easier separation, and cooperatively enhanced performances. However, the main problem lies in the tedious and costly synthetic route (including high temperature phosphating, complicated multi-step, and time-consuming reaction process), and the inherent shortcoming of the support that hinders effective separation and reuse of the catalyst.…”