Room-temperature Solid-state Synthesis And Catalytic Properties Of Iron Group Metal And Oxide Nanomaterials

Iron group metals and oxides with good electrical, magnetic, and chemical properties, such as Fe, Co, Ni, and their oxides, can be applied in the fields of energy storage, biology medicine, and catalysis and so on. In this thesis, a series of iron group metals, oxides, and composites nanomaterials have been synthesized by room-temperature solid-state chemical reactions. The applications of the obtained iron group nanomaterials as a catalyst in the reduction of 4-nitrophenol(4-NP) and the direct coal liquefaction were studied. It contains four parts:1. Metal nanoparticles, such as Fe, Co, Ni nanoparticles, and NiCo bimetal nanoparticles have been prepared by a room-temperature solid-state reaction between metal salts and NaBH4. The Ni nanoparticles with different structures have been obtained in variational conditions and they were used as a catalyst in the reduction of 4-NP. The results showed that room-temperature solid-state route can act as an efficient method to prepare metal nanomaterials; the morphology and catalytic property of Ni nanoparticles can be influenced by the additives.2. Ni/graphene(Ni/rGO) nanocomposites have been synthesized by room-temperatures solid-state reaction between nickel salts and NaBH4 in the presence of graphene oxide(GO). The obtained Ni/rGO nanocomposites have been used as a catalyst in the reduction of 4-NP. The results displayed that the simultaneous reduction of metal ions and GO has been achieved by the solid-state route. The obtained metal/graphene nanocomposites showed enhanced catalytic performance compare with metal nanoparticles. In addition, the catalytic activity of Ni/rGO nanocomposites is higher than that of Ag nanoparticles, but is lower than that of Ag/GO nanocomposites.3. Fe3O4 nanoparticles and Fe3O4/rGO nanocomposites have been prepared by room-temperature solid-state method. The synthesized samples were used as a catalyst in direct liquefaction of Heishan Coal. The results demonstrated that Fe3O4 nanoparticles obtained by solid-state method are active toward direct liquefaction of Heishan Coal. The conversion, oil yield, gas yield, and asphalt yield are 74.5 wt%, 55.4 wt%, 13.9 wt%, and 5.2 wt%, respectively. Fe3O4/rGO showed almost same activity compare with Fe3O4 nanoparticles in direct liquefaction of Heishan Coal. In addition, Dahuangshan Coal is more appropriate than Heishan Coal in direct liquefaction process with Fe3O4 nanoparticles. The best liquefaction condition of Dahuangshan Coal with Fe3O4 nanoparticles was confirmed.4. Fe/FeOOH hierarchical nanostructures have been synthesized by control oxidation of Fe nanoparticles obtained by reduction of FeCl2 through room-temperature solid-state method. The formation mechanism of Fe/FeOOH hierarchical structures and their applications in the field of direct coal liquefaction and wastewater treatment have also been studied. The results revealed that Fe/FeOOH hierarchical structures constituted ultrathin nanosheets can be obtained by the process of ―reduction-oxidation-ripening‖. The conversion, oil yield, gas yield, and asphalt yield are 92.8 wt%, 50.1 wt%, 21.9 wt%, and 20.8 wt%, respectively. The Fe/FeOOH hierarchical nanostructures have also demonstrated a good adsorption capability for the removal of Congo red(CR) and Cr(VI) ions from the contaminated water. The highest adsorption capacities of CR and Cr(VI) by the Fe/FeOOH hierarchical structures are 167.8 mg/g and 57.9 mg/g, respectively.