Junjie Jing

Facile route fabrication of nano-Ni core mesoporous-silica shell particles with high catalytic activity towards 4-nitrophenol reduction

A facile, environmentally friendly synthetic route was developed to prepare nano-Ni core mesoporous-silica shell particles. Ethylenediaminetetraacetic disodium salt (EDTA) was the chelating agent and thus controlled the nucleation rate of the nano-Ni core. In this work, EDTA was used to regulate the reduction rate of nickel acetate. Thereby, by varying the amount of EDTA utilized in reaction medium, the size of nano-Ni can be readily controlled in the range of 40–80 nm. The mesoporous silica shell was fabricated by the Stober method. The nano-Ni core mesoporous-silica shell particles were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). UV spectrophotometry (UV/vis) was used to analyse the growth mechanism of the nano-Ni cores. The as-synthesized nano-Ni core mesoporous silica shell particles were found to show a good catalytic activity towards the reduction of 4-nitrophenol to 4-aminophenol in the presence of an excess amount of NaBH4. The magnetic properties, catalytic mechanism and the possibility of reusability were also investigated.

Synthetic core–shell Ni@Pd nanoparticles supported on graphene and used as an advanced nanoelectrocatalyst for methanol oxidation

In this study, the uniform dispersion of new highly active Ni@Pd core–shell nanoparticle catalysts supported on graphene (Ni@Pd/graphene) was prepared via a two-step procedure involving a microwave synthesis method and a replacement method. Several characterization tools, such as X-ray powder diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) were employed to study the phase structures, morphologies and properties of the Ni@Pd/graphene composite. The results indicated that a uniform dispersion of Ni@Pd core–shell structure nanoparticles on graphene have an average particle size of 4 nm. The Ni@Pd/graphene composite was used as an electrocatalyst for alcohol oxidation in alkaline media for fuel cells. The electrocatalytic activity of Ni@Pd/graphene for ethanol oxidation is 3 times higher than that of the Pd/graphene electrocatalyst at the same Pd loading. The enhanced electrocatalytic properties could be attributed not only to the electric synergistic effect between Pd, Ni and graphene, but also the high use ratio of Pd due to its shell structure.

Ni/MWCNT-Supported Palladium Nanoparticles as Magnetic Catalysts for Selective Oxidation of Benzyl Alcohol

Well dispersed Pd@Ni bimetallic nanoparticles on multi-walled carbon nanotubes (Pd@Ni/MWCNT) are prepared and used as catalysts for the oxidation of benzyl alcohol. Scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy analysis, and X-ray diffraction were performed to characterise the synthesised catalyst. The results show a uniform dispersion of Pd@Ni nanoparticles on MWCNT with an average particle size of 4.0 nm. The as synthesised catalyst was applied to the oxidation of benzyl alcohol. A 99 % conversion of benzyl alcohol and a 98 % selectivity of benzaldehyde were achieved by using the Pd@Ni/MWCNT (Pd: 0.2 mmol) catalyst with water as a solvent and H2O2 as oxidant at 80°C. The catalytic activity of Pd@Ni/MWCNT towards benzyl alcohol is higher than that of a Pd/MWCNT catalyst at the same Pd loadings. The catalyst can be easily separated due to its magnetic properties.