Facile and low-cost synthesis route for graphene deposition over cobalt dendrites for direct methanol fuel cell applications Enas Taha Sayed a,b , Mohammad Ali Abdelkareem a,b,c, *, Hussain Alawadhi a,d , Tareq Salameh c , A.G. Olabi a,c,e , Abdul Hai Alami a,c, * a Center for Advanced Materials Research, University of Sharjah, 27272, Sharjah, United Arab Emirates b Chemical Engineering Department, Faculty of Engineering, Minia University, Egypt c Department of Sustainable and Renewable Energy Engineering, University of Sharjah, 27272, Sharjah, United Arab Emirates d Department of Applied Physics and Astronomy, University of Sharjah, PO Box 27272, Sharjah, United Arab Emirates e Mechanical Engineering and Design, School of Engineering and Applied Science, Aston University, Aston Triangle, Birmingham B4 7ET, UK ARTICLE INFO Article History: Received 21 July 2020 Revised 12 October 2020 Accepted 20 October 2020 Available online 5 November 2020 ABSTRACT In this work, standalone cobalt dendrites are prepared then doped with graphene flakes by a simple electro- plating technique. Microstructural examination using SEM with EDX, as well as Raman spectroscopy meas- urements, verified the successful formation of graphene. The prepared material exhibit a favorably high electrochemical methanol oxidation activity with an onset oxidation potential of 0.07 V vs. Ag/AgCl, which is significantly lower than that of the Ni (0.35 V vs. Ag/AgCl). The doping process causes a decrease in the ohmic resistance of the material from 3.2 Ohm cm À2 to 2 Ohm cm À2 , which consequently resulted in a significant increase in the current density from 35 mA cm À2 to 62 mA cm À2 using 1 M methanol at 0.5 V vs. Ag/AgCl. After two hours of current discharge at 0.5 V vs. Ag/AgCl, the catalyst doped with graphene showed a current density of 62 mA cm À2 . This is an eight-times higher than that obtained in the case of the Ni nano-powder. An electrode prepared by depositing the catalyst on the surface of a highly conductive porous Ni foam was successfully used as the anode of a passive air cathode direct methanol fuel cell, demonstrating an open cir- cuit voltage of 0.75 V using 0.25 M methanol in 1 M KOH. © 2020 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved. Keywords: Co dendrites Methanol oxidation Graphene doping Onset potential Two-electrode cell structure Direct methanol fuel cell 1. Introduction The environmental changes and the heath problem resulted from the usage of fossil fuel urge the scientists overall the world to increase the efficiency of the current technologies [1,2] and/or search for alternative fuels that are sustainable and have low or no environ- mental impacts [3,4]. The technological advances in developing dif- ferent types of renewable energies proved their potential to partially replace fossil fuel in the near future and totally in the long term in various applications [5À7]. Among the different renewable energy sources, biomass is the most attractive one due to its role in waste management [8À10]. Bio-methanol could be produced from different wastes such as sugar cane bagasse [11], CO 2 reduction [12], and other biomass resources [13]. The direct combustion of the methanol as a source of energy is restricted with the low energy conversion in tra- ditional energy conversion devices. The dependent on methanol as a green fuel can be realized through the development of devices that can efficiently convert its energy content into electricity. Fuel cells are emerging electrochemical energy conversion devices used to direct conversion of the chemical energy of the fuel into electricity [14]. Fuel cells are small in size, have no moving parts, and environ- mentally friendly [15À18]. According to the operating temperature, fuel cells are classified into low-, medium-, and high-temperature fuel cells. Direct methanol fuel cells (DMFCs) operating at low tem- peratures have high energy density [19]. It is considered a promising candidate for replacing Li-ion batteries and other secondary batteries soon [20, 21]. The usage of Pt-based catalysts and the methanol cross over are the main challenges that restricted the commercialization of DMFC S . Pt is found in limited amounts and suffers from the CO poi- soning that is formed during the electrochemical oxidation of metha- nol on its surface [22,23]. The commercialization of the DMFC requires preparing an effi- cient and cost-effective non-precious catalyst that could replace the current Pt catalyst at both anode and cathode of the DMFCs. Despite significant progress in preparing non-precious cathode catalysts such as nitrogen-doped graphene materials [24,25], scientists are still looking for a non-precious anode catalyst. Ni is considered the best catalyst for methanol oxidation in alkaline media. However, the application of Ni is limited by its high onset potential of 0.35 V vs. Ag/ AgCl as well as low catalytic activity [26]. Various strategies have * Corresponding authors. E-mail addresses: mabdulkareem@sharjah.ac.ae (M.A. Abdelkareem), aalalami@sharjah.ac.ae (A.H. Alami). https://doi.org/10.1016/j.jtice.2020.10.019 1876-1070/© 2020 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved. Journal of the Taiwan Institute of Chemical Engineers 115 (2020) 321À330 Contents lists available at ScienceDirect Journal of the Taiwan Institute of Chemical Engineers journal homepage: www.elsevier.com/locate/jtice