Synergistic Effect of Urea on Vitamin C Electro-Oxidation at NiOx/CoOx Binary Catalysts Supported on Graphene Nanosheets

• Main Authors: El-Deab, M.S (Author), El-Nowihy, G.H (Author)
• Format: Article
• Language: English
• Published: IOP Publishing Ltd 2022
• Subjects: Blending; Catalyst activity; Catalytic mediation; Cyclic voltammetry; Electrocatalysts; Electrodes; Electron transport properties; Electrooxidation; Electrooxidations; Energy conversion; Fuel blends; Fuel utilization; Fuels; GC electrode; Graphene; Graphene nanosheet.; Graphene nanosheets; Graphene nanosheets.; Metabolism; Metal nanoparticles; Molecules; Nanosheets; Nickel compounds; Synergistic effect; Transition metal oxide nanoparticles; Transition metal oxides; Transition metals; Urea; Vitamin C
• Online Access: View Fulltext in Publisher

 The electro-oxidation of ascorbate (AAO) in the presence of urea at NiOx/CoOx/GNs/GC electrode is investigated. Cyclic voltammetry measurements show that the peak current (Ip) of AAO at NiOx/CoOx/GNs/GC electrode is ten times that of GNs/GC electrode. This highlights the role of catalyst composition and order of deposition on the activity of AAO. Interestingly, blending ascorbate (AH-) with urea caused a significant promotion of AAO. Both the Ip of AAO and the fuel utilization in the AH-/urea fuel blend solution are doubled when compared to those obtained at the same electrode in pure AH-solution (in addition to a favorable negative shift in the onset potential, Eonset = 150 mV). Urea molecules are believed to act as anchoring molecules for AH-molecules at the NiOx/CoOx/GNs/GC surface with a favorable geometry facilitating its oxidation (by two-electron transfer process) to dehydroascorbate (DHA). Four interaction geometries are proposed, and comparative DFT calculations are conducted, displaying the relative stability and dipole moments of AH-in such a way that facilitates its adsorption and oxidation. These findings demonstrate the crucial role of the catalysts tailoring together with the selection of a smart blending fuel with AH. © 2022 The Electrochemical Society ( ECS ). Published on behalf of ECS by IOP Publishing Limited