Application of conjugated cucurbit[8]uril porphyrin supramolecular assembly in electrochemical hydrogen generation

Abstract

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.