## 1 Introduction  
Owing to the world energy crisis and fossil fuels depletion, the development of renewable alternative energy sources and technologies such as fuel cells (FCs), solar cells, and wind energy are presently being researched throughout the world [1]. FCs have received much attention recently due to their great range of benefits, for example high efficiencies, low emission, and fuel flexibility [2; 3; 4]. The most famous FC is the H\({}_{2}\)-O\({}_{2}\) system, however using H\({}_{2}\) as a fuel has many drawbacks related to its explosive and flammable nature, so it is neither easy to transport nor store [2; 3; 4]. As a result, there are many other organic molecules that have been proposed to replace H\({}_{2}\) in the FCs such as methanol, ethanol, and glucose [2; 3; 4]. Methanol as a fuel has many advantages over H\({}_{2}\) such as low-cost, availability, ease of storage, and transport. Therefore, direct methanol fuel cells (DMFCs) are considered as one of the best choices for future clean energy sources [5; 6]. The electrooxidation of methanol is considered the key step in DMFCs in both alkaline and acidic fuel cells, and the commercialization of DMFCs is limited in part by the durability, scarcity, and high cost of the Pt-based methanol electrooxidation catalysts [5; 6]. Pt and Pt-based materials are the most famous catalysts for methanol electro-catalytic oxidation in the DMFCs, especially in the low temperature FCs (both alkaline and acidic) [6; 7]. However, the formation of poisoning intermediates that are adsorbed strongly on the catalyst surface (e.g., CO\({}_{\text{ad}}\) and other carbonaceous materials), which are generally produced during the methanol oxidation process, can in the long run hamper the electrooxidation reaction and deteriorate the electrocatalytic activity of the catalyst, which finally results in a severe failure of FCs as a whole [6; 7]. Recently, researchers' attention has been devoted to non-Pt based transition metal oxide catalysts for methanol oxidation in alkaline medium such as NiOx, CoOx, CuOx, AgOx and FeOx, which are characterized by good electrocatalytic activity, stability, and low poisoning ability in alkaline medium [8; 9; 10; 11; 12; 13; 14]. Among the aforementioned materials, NiOx [8], CuOx [10], and CoOx [11] have been considered the most prominent electrocatalysts for methanol oxidation in alkaline medium. NiOx has shown high electrocatalytic activity towards alcohol oxidation in alkaline medium and this high activity is attributed to the unpaired 'd' electrons and vacant d-orbitals associated with the oxidized form of nickel oxy-hydroxide (NiOOH), which has been extensively engaged in many electrocatalytic processes [15]. On the other hand, CuOx, with different fabrication methods and morphologies, has shown very good results towards methanol and glucose oxidation in alkaline medium [10; 16; 17]. In addition, alloying CuOx with NiOx demonstrated a synergistic effect towards methanol oxidation that was attributed to the suppression of the \(\gamma\)-NiOOH phase formation along with the stabilization of the \(\beta\)-NiOOH phase, of which the latter is the active phase in alcohol oxidation processes in alkaline medium [18]. Furthermore, CoOx alone is not considered as a good electrocatalyst, but it has shown good electrocatalytic activity and stability for alcohol oxidation when it is alloyed with NiOx [19]. For these reasons the tertiary alloy of CuCoNiOx is expected to exhibit high electrocatalytic activity and stability towards methanol oxidation in the alkaline DMFCs. In this context, there is only one article published recently that reports the synergistic effect between the three metal oxides if they are present in the same alloy towards methanol oxidation in alkaline medium [20]. According to this report, CuCoNi (copper-cobalt-nickel ternary nanostructures) modified graphite electrode G/NiCuCo has shown better electrocatalytic activity towards methanol oxidation in comparison to G/Cu, G/Ni, G/Co, G/CuCo, G/NiCo, and G/CuNi [20].