Fabrication Of Metal Oxides Nanomaterials For Energy And Catalysis Applications By Atomic Layer Deposition

As an advanced technology for depositing thin films, atomic layer deposition (ADD) has shown promising feature in nanomaterials, energy conversion and storage, and catalysis, due to its simplicity, reproducibility, excellent control of the layer thickness at atomical scale, and the high conformality of the obtained films. In this present dissertation, NiO and VOx nanoparticles with controlled size and compositions were deposited onto the nanoporous substrates. The supercapacitive and catalytic performances of these materials were measured. The brief introduction is described as following.1. NiO/Nanoporous Graphene Composites with Excellent Supercapaci-tive Performance Produced by Atomic Layer DepositionBecause of its high theoretical specific capacitance of2573F/g and low cost, nickel oxide (NiO) has attracted much attention for energy storage applications, which make it a promising electrode material for supercapacitors. However, the low electronic conductivity and poor long-term stability of NiO limited its practical applications. To overcome these limitations, an efficient atomic layer deposition (ALD) method was here demonstrated for the fabrication of NiO/nanoporous graphene (NG) composites as electrode materials for supercapacitors. The eletrode materials have been characterized by X-ray diffraction、transmission electron microscope、X-Ray Photoelectron Spectrometer and Raman spectroscopy. The results indicated that NiO crystallite sizes can be simply controlled by adjusting the number of ALD cycles. And the electrochemical measurements revealed that the NiO/NG composites prepared by ALD exhibited elegant specific capacitance of up to approximately1005F/g at a current density of1A/g. Furthermore, electrochemical performance of the NiO/NG composites is found to strongly depend on the size of NiO nanoparticles.2. Fabrication of VOx-based catalyst for Dehydrogenation of ethylbenzene by ALDA series of VOx catalysts were fabricated by ALD technology for dehydrogenation of ethylbenzene under CO2atmosphere. In this oxidative dehydrogenation process, CO2were used as the oxidant to displace oxygen. It’s a green chemical approach to take full advantage of CO2resources and then reduce power consumption. Due to the addition of CO2, which can promote the dehydrogenation of ethylbenzene to the right side, the ethylbenzene conversion and styrene yield were enhanced. Silica nanotubes (SiNT) with mesoporous shells were selected as support for VOx deposition because of its high surface area and mesoporous channels, which are very favorable for mass transfer and catalytic reactions. The effect of deposition order and number of ALD cycles of VOx and SbOx on the catalytic performance of SiNT-SbV for dehydrogenation of ethylbenzene were investigated. The SiNT-Sb5V5o prepared by first deposition5SbOx ALD cycles and then50VOx ALD exhibited the highest ethylbenzene conversion rate (31.15%) and the selectivity of styrene was98%. The catalysts suffer deactivation during reaction probably due to the coke deposition and the formation of lower oxidation state vanadium oxide.