ABSTRACT
Direct methanol fuel cells (DMFCs) have gained much attention because of their simple structure, environment friendliness, and highly suitable for portable devices, including cellular phones, laptops, notepads, and cameras. DMFCs have been rec- ognized as the future power generation source that can replace the conventional lithium-ion batteries because of their higher energy density (5.04 kWh L-1), easy storage ability, transportability, and low cost [1]. It is the modified form of proton exchange membrane fuel cells (PEMFCs), in which polymer electrolyte membranes are used to separate anode and cathode chambers [2]. Unlike PEMFC, methanol can be directly used in DMFC without using reformer subsystems, and the fuel can be stored under atmospheric pressure [3]. However, commercialization of DMFC is still difficult because of the following reasons: methanol crossover across the membrane, 262high cost, carbon monoxide (CO) poisoning, and short-term durability of the electro- catalyst. The significant fuel crossover through the electrolyte membrane reduces the efficiency and cell performance [1, 4] . The performance of DMFC largely depends on the selection of proper cost-effective anode catalyst that can increase the metha- nol oxidation rate and reduce CO poisoning. Usually, the pure platinum (Pt) is known as an effective anode catalyst because of its effective dissociation and adsorption of methanol molecules; however, methanol oxidation produces carbonaceous inter- mediates, which block the electrode surface, causing poisoning of Pt-based elec- trodes [5]. Moreover, the high cost of Pt-based catalysts is another limitation for commercialization of DMFC. Therefore, researchers have made continuous efforts to develop a Pt-free anode catalyst using palladium, nickel, transition metal-based compounds, etc.
