Chemical Engineering publications

Permanent URI for this collection

https://hdl.handle.net/2440/758

Browse

Browsing Chemical Engineering publications by Author "Abdel-Azeim, S."

Now showing 1 - 2 of 2
  • No Thumbnail Available
    ItemMetadata only
    Compact, flexible conducting polymer/graphene nanocomposites for supercapacitors of high volumetric energy density
    (Elsevier, 2018) Moussa, M.; El-Kady, M.F.; Abdel-Azeim, S.; Kaner, R.B.; Majewski, P.; Ma, J.
    Graphene is extensively utilized in energy storage devices because of its high surface area and electronic conductivity as well as ease of electrode fabrication. But graphene sheets often stack themselves in polymeric matrices leading to poor capacitive performance. This problem was addressed herein by developing and inserting respectively two types of nano-sized conducting polymers into graphene interlayer spacing. The resulting hydrogel composite electrodes demonstrated efficient electron transfer for fast and reversible Faradaic reactions at the interface. Theoretical modelling by the density functional theory suggested that the reduction involve 2Hþ transfer steps from polyaniline to graphene oxide: the first step would be an epoxy-ring opening process after activation of the CeO bond, and the second step would be CeO rupture leading to a de-epoxidation process. This binder-free electrode demonstrated high cycling performance and ultrahigh volumetric capacitance of 612 F cm3 , being 10 times higher than the activated carbon used in the current industry. The study represents a step forward towards the fabrication of flexible, high-energy density supercapacitors.
  • No Thumbnail Available
    ItemOpen Access
    Molybdenum nitride nanocrystals anchored on phosphorus-incorporated carbon fabric as a negative electrode for high-performance asymmetric pseudocapacitor
    (Elsevier, 2019) Dubal, D.; Abdel-Azeim, S.; Chodankar, N.; Han, Y.
    Pseudocapacitors hold great promise to provide high energy-storing capacity; however, their capacitances are still far below their theoretical values and they deliver much lower power than the traditional electric double-layer capacitors due to poor ionic accessibility. Here, we have engineered MoN nanoparticles as pseudocapacitive material on phosphorus-incorporated carbon fabric with enhanced ionic affinity and thermodynamic stability. This nanocomposite boosts surface redox kinetics, leading to pseudocapacitance of 400 mF/cm² (2-fold higher than that of molybdenum nitride-based electrodes) with rapid charge-discharge rates. Density functional theory simulations are used to explain the origin of the good performance of MoN@P-CF in proton-based aqueous electrolytes. Finally, an all-pseudocapacitive solid-state asymmetric cell was assembled using MoN@P-CF and RuO₂ (RuO₂@CF) as negative and positive electrodes, respectively, which delivered good energy density with low relaxation time constant (τ₀) of 13 ms (significantly lower than that of carbon-based supercapacitors).