Great efforts have been made to research of different materials to improve this Fuel Cell performance. Graphene materials have been attracted great interest in their electrical and barrier properties. CVD Graphene monolayer is an excellent electronic conductor in-plane and impermeable to all species except the protons through the plane. Graphene oxide has been demonstrated to be an ionic conductor but impermeable to dry gases and electrons. Graphene oxide is an organophobic material, property which makes this material as a good barrier.
Different studies have been carried out for The University of Manchester to prove that incorporate CVD Graphene, Reduced Graphene Oxide (rGO) and Graphene oxide (GO) into the different layer of the PEM fuel cell Membrane Electrode Assemblies (MEAs) [1,2].
GO has been added as a barrier layer in Direct Methanol Fuel Cells providing additional tortuosity and decreasing the methanol crossover, one of the most important inconvenient in this type of PEM fuel cells. rGO has been incorporated as a catalyst support obtaining an important improvement in the methanol oxidation reaction.
Several graphene preparation methods have been developed, such as chemical vapour deposition (CVD), arc discharge, segregation growth or Hummers method. However, the requirements of expensive equipment used, extreme reaction conditions and the usage of highly toxic chemicals are some of the inconvenient that these techniques present. Then, the synthesis of graphene in both high quality and quantity via economic ways is one of the most important challenges nowadays for practical applications. Electrochemical exfoliation of graphite has been presented as a green and cost-effective approach for producing high quality of graphene in high yield using simple equipment [3-5].
This work presents an alternative to Hummer’s method to produce GO and rGO by Electrochemical Exfoliation of Graphite. A simple two electrodes configuration, counter electrode and working electrode in different electrolyte solutions, NH4NO3, (NH4)2 SO4, has been carried out to produce this GO. Figure1 shows preliminary characterization results of GO produced by electrochemical exfoliation (EGO) using NH4NO3 as electrolyte. Single flakes of GO can be observed in the TEM image. Raman spectra and their ID/IG ratio show that EGO presents a good quality compared with Hummer’s method.
GO produced by Electrochemical Exfoliation will be incorporated into different MEAs layer to obtain an enhanced performance of low temperature fuel cell. GO. Effect of GO on the fuel cell was studied by electrochemical characterization.
References:
[1] Stuart M. Holmes, Orabhuraj Balakrishnan, Vasu. S. Kalangi, Xiang Zhang, Marcelo Lozada-Hidalgo, Pulickel M Ajayan, Rahul R. Nair. 2D Crystals Significantly Enhance the Performance of a Working Fuel Cell. Advance Energy Materials, 7, (2017).
[2] S. Al-Batty, C. Dawson, S. P. Shanmukham, E. P. L. Roberts and S. M. Holmes. Improvement of direct methanol fuel cell performance using a novel mordenite barrier layer. J Mater. Chem. A, 2016, 4, pp. 10850-10857.
[3] Richard Gondosiswanto, Xunyu Lu, and Chuan Zhao. Preparation of Metal-Free Nitrogen-Doped Graphene via direct electrochemical exfoliation of graphite in ammonium nitrate. Australian Journal of Chemistry, 68 (2015) 830-835.
[4] Xunyu Lu and Zhao. Controlled electrochemical intercalation, exfoliation and in-situ nitrogen doping of graphite in nitrate-based proton ionic liquids. Physical Chemistry Chemical Physics,15 (2013), 30005-200009.
[5] Khaled Parvez, Ahong-shuai Wu, Tongjin Li, Xianjie Liu, Robert Graft, Xinliang Feng, and Klaus Mullen. Exfoliation of Graphite into Graphene in Aqueous solution of Inorganic Salts. Journal of the American Chemical Society, 136, (2014), 6038-6091.