Browsing by Author "Aoudi, Bouthaina"

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Open Access
Application of conjugated cucurbit[8]uril porphyrin supramolecular assembly in electrochemical hydrogen generation
(2020-08) Aoudi, Bouthaina
The ever-increasing demands for energy have encouraged an enormous consumption of fossil fuels worldwide. This has presented major concerns due to their limited resources and serious environmental issues. Therefore, the search for an alternative clean energy fuel has been intensively under study. In the past decade, hydrogen has attracted great attention as a promising fuel for the future. Hydrogen is an eco-friendly fuel that is readily abundant, highly efficient and clean since water is its only combustion product. Herein, this thesis highlights the synthesis and characterization of a novel supramolecular assembly based on cucurbit [8] uril -porphyrin functionalized on electrochemically reduced graphene oxide sheets for application in electrochemical hydrogen evolution. The study conveys optimization procedures for choosing the best catalytic system. Electrochemical analysis including potentiometry, cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy were used to evaluate activity and stability. Characterization techniques were also performed to analyze the morphology and chemical structures of composites. Electrochemical studies demonstrated that ERGO: Ni-P composite (which comprises of a layer of graphene oxide drop-casted on FTO followed by a layer of nickel CB[8]-porphyrin) can serve as an excellent electrocatalyst for hydrogen evolution in alkaline medium. The composite exhibited high activity (onset potentialv -20 mV, 56.9 mmol h−1g −1 hydrogen, faradaic efficiency of 93% ), remarkable rate of charge transfer (Rct v 210 Ω), large electrochemical surface area (Cdl v1.67 mFcm−2 ) and significant stability without requiring additional noble metals.
Open Access
In situ-Electrochemically reduced graphene oxide integrated with cross-linked supramolecular polymeric network for electrocatalytic hydrogen evaluation reaction
(Elsevier, 2021-08-26) Aoudi, Bouthaina; Khaligh, Aisan; Sheidaei, Yasaman; Tuncel, Dönüş
Herein, we report the synthesis of a new supramolecular polymeric network (PCN) assembled through crosslinking of propyl bromide substituted tetraphenyl porphyrin with perhydroxy-cucurbit [8]uril and its use in the electrocatalytic hydrogen evaluation reaction after loading with nickel and integrating with in situ-electrochemically reduced graphene oxide (ERGO). Electrode was prepared by first coating graphene oxide on the FTO substrate followed by layering the nickel loaded PCN and finally by applying an appropriate voltage to reduce the graphene oxide in situ electrochemical reaction. The loading of nickel cocatalyst into PCN together with the integration of ERGO layer substantially improved its HER efficiency. Effect of various concentrations of Ni and GO on the HER activity of the developed electrocatalyst were investigated. Therein, ERGO1/Ni2@PCN catalyst containing 41% Ni and 50% GO (with respect to PCN) with only one layer of each component demonstrated excellent HER activity and stability with low onset and overpotentials of −20 mV, η@10 mA cm−2 of −360 mV, respectively, and remarkable hydrogen generation rate of 27.5 mmol h−1 g−1 in 1 M KOH. This noble-metal-free catalytic system is simple yet highly promising for the efficient hydrogen evolution reaction from water splitting.