| Life’s comforts over the past two centuries have been derived largely from the discovery and exploitation of fossil fuels, and the result of profound scientific and technological innovations. Whereas the creation of oil, coal, and natural gas reserves—the primary fuels for transportation—occurred over several hundred millions of years, we are on course to consume these non-renewable energy sources within several hundreds of years. Notwithstanding the unknown medium-to-long term implications of burning carbonaceous fuels and CO2 emissions on a warming planet,it is abundantly clear that scientific and technological solutions are urgently required to avert a looming energy crisis of epic proportions.The clean energy hydrogen whose combustion product is only water, is one of the candidates can replace fossil fuels, and has been gotten wide attention in recent years. In hydrogen production technology, however, the catalytic activity of catalysts has become the priority. As the same time, the lithium ion battery as a new type of energy storage device, which is used in electric vehicles, has been developed rapidly.Improve the electrochemical performance of electrode materials is the motivation for accelerating the practical application of lithium ion battery. Metal/metal oxide-graphene composite materials, not only combine the excellent properties of graphene, also has the characteristics of metal/metal oxide, which can be effectively applied to produce hydrogen and lithium ion battery technology.Considering the above research background, the metal/metal oxide-graphene composites were synthesized via a hydrothermal method by using graphene oxide(GO) as a precursor. The nanocomposites were characterized by X-ray power diffraction(XRD), transmission electron microscopy(TEM), Raman spectra, X-ray photoelectron spectroscopy(XPS), and fourier transform infrared(FTIR)spectroscopy. We also investigated their electrochemical performance of lithium ion batteries and catalytic activity of hydrogen production.Magnetic core-shells were fabricated with Co nanoparticles(NPs) as cores and g-C3N4 as shells. In the fabrication process, the Co@g-C3N4 core-shells wereanchored onto the r GO nanosheets to form a Co@g-C3N4-rGOcomposite(CNG-I).For hydrogen generation from hydrolysis of NaBH4 or NH3BH3, the Co NPs as cores play a role of catalytic active sites. The g-C3N4 as shells protects Co NPs cores from aggregating and growing. The existence of g-C3N4 shells also strengthens the connection between Co NPs and rGO to prevent them from leaching or flowing away.The unique property of g-C3N4 helps them become an effective cocatalyst for hydrogen generation. The magnetism of Co NPs and shape of rGO nanosheets achieve the momentum-transfer in the external magnetic field. In batch reactor, higher catalytic activity was obtained with CNG-I in self-stirring mode than magneton-stirring mode. In continuous-flow process, stable hydrogen generation was carried out with CNG-I being fixed and propelled by the external magnetic field. The separation film is not necessary due to the effective magnetic momentum-transfer.This idea of composite design and magnetic momentum-transfer will be useful for the development of hydrogen generation and multifunctional composite materials.Fe2O3-TiO2-r GO(FTG) was synthesized through a hydrothermal method. The results of lithium ion battery performance test showed that FTG as the electrode material has a specific capacity of 410 mA h g-1 after 300 cycles of charge and discharge at 0.2 C. Even after 130 cycles of charge and discharge at different rate, the finally specific capacity was closed to the initial capacity, indicating that FTG possessed good rate capability. |
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