Sol-gel derived nanostructure materials with possible applications in catalysis and energy storage

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Aerogels are a unique class of materials, with mesoporous architectures that are composed of interconnected nanoparticles to form highly porous, high surface area, and low density structures. While there are various sol-gel methods that can be used to synthesize aerogels, here we utilized epoxide-addition technique to fabricate sol-gel metal oxide nanomaterials. This approach is an alternative for the well-established alkoxide method and eliminates the necessity to use costly sensitive metal alkoxide precursors. This technique provides a synthetic toolbox for materials scientists to synthesize porous nanomaterials with tailored unique properties that are simply controlled by modifying synthetic parameters. Herein, we utilized epoxide-addition approach to synthesize and tune the physical and chemical properties of porous copper oxide aerogels, a series of first transition metal ferrite aerogels (including cobalt ferrite, nickel ferrite, copper ferrite and zinc ferrite), and indium-tin oxide (ITO) aerogels. Copper in variable oxidation states and ferrite materials have been well known for their application in heterogenous catalytic reactions, such as Fischer-Tropsch, CO2 hydrogenation, and water-gas shift reaction. The synthesized porous materials discussed herein all showed high surface area, significant porosity, and high reducibility which are the three most important factors for each catalyst.
ITO is the most widely used transparent semiconductor in industry. Although there have been reports on preparing mesoporous ITO nanomaterials using sol-gel methods, all of them exhibit poor electrical conductivity which is considerably lower than the single crystal ITO material. We were able to improve the conductivity of the synthesized mesoporous ITO nanomaterials by several orders of magnitude by altering the tin content in the materials. The morphology and the particle size of the synthesized ITO materials were modified by subtle changes in the tin concentration. Altogether, this work shows the capability of epoxide-addition approach in synthesizing and modifying the properties of sol-gel metal oxides for different industrial applications.

Sol-gel chemistry, Nanomaterials, Epoxide-addition method, Porous metal oxide nanoparticles