Vermiform Ni@CNT derived from one-pot calcination of Ni-MOF precursor for improving hydrogen storage of MgH_(2)

The Ni-coated carbon nanotubes(Ni@CNT)composite was synthesized by the facile“filtration+calcination”of Ni-based metal−organic framework(MOF)precursor and the obtained composite was used as a catalyst for MgH_(2).MgH_(2)was mixed evenly with different amounts of Ni@CNT(2.5,5.0 and 7.5,wt.%)through ball milling.The MgH_(2)−5wt.%Ni@CNT can absorb 5.2 wt.%H_(2)at 423 K in 200 s and release about 3.75 wt.%H_(2)at 573 K in 1000 s.And its dehydrogenation and rehydrogenation activation energies are reduced to 87.63 and 45.28 kJ/mol(H_(2)).The in-situ generated Mg_(2)Ni/Mg_(2)NiH4 exhibits a good catalytic effect due to the provided more diffusion channels that can be used as“hydrogen pump”.And the presence of carbon nanotubes improves the properties of MgH_(2)to some extent.

Dual template-induced construction of three-dimensional porous SiO_(2)/NC/Co-CNTs heterostructure with highly dispersed active sites for efficient oxygen evolution reaction

The development and exploration of efficient and economical electrocatalysts for oxygen evolution reaction(OER)represents the main bottleneck to unlocking a sustainable energy scenario based on elec trocataly tic water splitting.Nano scale integration of three-dimensional(3D)porous heterostructure with highly dispersed active sites and good structural stability is challenging.Herein,a dual template route is developed to construct the 3D porous SiO_(2)/nitrogen-doped carbon(NC)/Co-carbon nano tubes(CNTs)hetero structure.Importantly,the hard template(SiO_(2) nano spheres)contributes to 3D porous structure,increases the specific surface area,and promotes the contact area of the electrolyte.At the same time,the soft template(basic zinc carbonate)can control the growth of 1D CNTs and facilitate the exposure of the active sites.Apparently,3D porous SiO_(2)/NC/Co-CNTs hetero structure inherits highly dispersed Co nanoparticles coated by NC.CNTs conductive channels and abundant N hetero atoms doping are reasonably constructed by a dual template strategy.Therefore,SiO_(2)/NC/Co-CNTs catalyst provides an extraordinary activity for the OER in alkaline media,with a low overpotential of 298 mV at a current density of 10 mA·cm^(-2).Furthermore,SiO_(2)/NC/Co-CNTs hetero structure enables excellent long-term durability with a 10 mV decay in overpotential after 3000 cyclic voltammetry cycles,and 97%remain in current density over 20 h.It is believed that this dual template strategy can provide a new and simple way to construct a highly dispersed active site in electrocatalysts.

Preparation of in-plane anisotropy Ni_(80)Co_(20)/Bi multifilms

A series of Au/[NiCo/Bi]x/Au （x = 2, 3） films were fabricated by pulsed laser deposition method. In order to induce the in-plane uniaxial magnetic anisotropy （IPUMA） of the multifilms, multiple layers and different oblique angles ranging from 0° to 30° for the substrate are applied during the deposition. The microstructures of the nanofilms were investigated by using X-ray diffraction （XRD） and transmission electronic microscope （TEM）. And their magnetic properties were measured by an alternating gradient magnetometer. For the multicycle systems, using the method that with more periodic structures of NiCo/Bi film is easier for inducing IPUMA than the less or the samples located with various angles.

Synthesis temperature dependence of morphologies and properties of cobalt oxide and silicon nanocrystals

Cobalt and cobalt oxide nanocrystals were synthesized on Si substrates from aqueous cobalt nitrate [Co（NO3）2·6H2O] powder via chemical vapor deposition method. Scanning electron microscope, field emission scanning electron microscope, and transmission electron microscope observations show different morphologies, such as continuous films, nano-bars, nano-dices, and nano-strings, depending on the synthesis temperature. The crystal structure characterization was conducted using X- ray diffraction methods. Furthermore, the properties of the samples were characterized using Raman spectroscopic analysis and vibrating sample magnetometer. The morphology change was discussed in terms of synthesis environments and chemical interactions between cobalt, oxygen, and silicon.