(Digital Presentation) Facile Fabrication of Graphene Quantum Dot- Doped Polyaniline Embedded Cu Metal-Organic Frameworks Composite Electrode As Improved Anode Electrocatalyst for Methanol Oxidation
Authors: Pashazadeh Sara , Habibi Biuck , Pashazadeh Ali , Fatemi Ali , Rasouli Milad 
Published: July 2022

Nonrenewable energy sources accounted for roughly 80% of total energy consumption [1]. Solar energy, wind energy, geothermal energy, hydropower, and fuel cells (FCs) have all recently been described as renewable energy sources. In commercial uses, renewable energy has experienced meteorological and logistical obstacles. Because of advantages such as simple fabrication/operation conditions, eco-friendly, high energy conversion efficiency, and long-term durability, FCs technologies are considered one of the most important renewable energy sources for many applications such as portable devices, cars, and electricity plants [2–5]. Methanol can be utilized in direct methanol fuel cells (DMFC) to produce clean energy that can be used in smart electronic gadgets or small automobiles in this regard [6]. However, before DMFC can be used commercially, the slow oxidation kinetics and catalyst toxicity [7] must be resolved. Therefore, the development of direct methanol fuel cells (DMFCs) is one of the most promising technologies for the applications of these devices in stationary power supplies and electric vehicles [8]. Apart from the future of mobile devices such as mobile chargers, phones, computers, and many other applications, this energy is environmentally benign because no gases are emitted and the waste is simply clean water. The biggest issue that this technique may encounter is its high cost due to the usage of noble metal catalysts (platinum (Pt) and ruthenium (Ru)) [9]. Methanol is oxidized via a multi-electron process and several products and/or intermediates can be formed, depending on the electrolyte and the nature of the electrode. Electrode materials are important parameters in the electrochemical oxidation of methanol, where high efficient electrocatalysts are needed. Several metal oxides such as Fe2O3, CeO2, MoOx, Co3O4, NiO, and CuO has been used in various applications, such as catalysis, water splitting photocatalysis, solar cells and gas sensing, besides their uses to enhance the electrocatalytic activity for methanol oxidation [10-11].

This paper describes the preparation of graphene quantum dot-doped polyaniline embedded copper metal-organic frameworks composite catalysts for investigating methanol oxidation in alkaline solutions. The electrode surface was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and electrochemical impedance spectroscopy (EIS). After physicochemical characterizations of graphene quantum dot-doped polyaniline embedded copper metal-organic frameworks composite modified carbon ceramic electrode (Cu- MOF/GQDs-PAN/CCE), its electrocatalytic and stability characterizations toward methanol oxidation in alkaline media were investigated in detail by cyclic voltammetry and chronoamperometry. Results showed that, the electrocatalytic activity of the Cu- MOF/GQDs-PAN/CCE electrode is much higher than those of unmodified electrode under similar experimental conditions, showing the possibility of attaining good electrocatalytic anodes for fuel cells. Kinetic parameters such as the electron transfer coefficient (α) and the number of electrons involved in the rate determining step (nα) for the oxidation of methanol were determined utilizing cyclic voltammetry (CV).

Keywords: Graphene quantum dot, Polyaniline, Metal-organic frameworks, electrocatalyst, Methanol

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