Synthesis and Extensive Characterization of Mesoporous Graphene-based Nanomaterials For Renewable Energy and Environmental Applications

Graphene-based nanomaterials including few-layer graphene oxide, reduced graphene oxide, three-dimensional scaffolds of graphene and graphene-carbon nanotube aerogels and their nitrogenated counterparts are synthesized using environmentally friendly methods. These nanomaterials are extensively characterized in terms of surface morphology and structure using electron microscopy, optical and vibrational techniques which provided microscopic structure and unprecedented physical properties useful for electrochemical energy storage and water desalination. Raman spectroscopy (RS) provided lattice dynamical structural characterization at nanoscale revealing collective atomic/molecular motions and localized vibrations. We analyzed Raman spectra in terms of prominent band position and intensity ratio that help to quantify microscopic stress/strain, structural disorder, number defect density, respectively. Photoluminescence excitation (room temperature luminescence with varying excitation wavelength) spectra revealed the electronic band structure such that distinct localized pi electrons were found in-between the band gap for the functionalized graphene. In addition, we have used advanced electrochemical microscopy technique to investigate dynamic physicochemical processes occurring at the surface of these exotic graphene-family nanomaterials and at the solid/liquid (electrode/electrolyte) interface. We discuss our experimental findings in terms of the multiple roles of oxygen and nitrogen functional groups and establish (micro)structure-property-activity relationship, relevant for alternative energy, catalysis, sensing and water treatment, to name a few