Evaluation of iron-based alloy nanocatalysts for the electrooxidation of ethylene glycol in membraneless fuel cells

The development of efficient and sustainable electrocatalysts for power conversion devices that generate electricity is essential to alleviate the energy crisis. In this work, carbon-supported iron-group alloy nanocatalysts composed of iron, cobalt and nickel with different atomic ratios were synthesized by a two-step reduction method. The morphology and composition of synthesized alloy nanocatalysts were studied by various physicochemical characterization techniques such as X-ray diffraction, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The X-ray diffraction studies showed a well-mixed solid-solution structure rather than a phase-separated structure for the ternary metals. Furthermore, transmission electron micrographs revealed that carbon-supported iron alloy samples displayed a homogenous dispersion with a particle size of 13–30 nm. The results of electrochemical analyses such as cyclic voltammetry, linear sweep voltammetry and chronoamperometry showed that nickel-containing alloy samples exhibited significantly higher electrochemical activity than non-nickel-alloyed samples. In a single membraneless fuel cell, the alloy nanocatalysts were tested as anodes for the electro-oxidation of ethylene glycol to evaluate their durability and effectiveness at room temperature. The single cell test revealed that the performance of the ternary anode is superior to that of their counterparts, which is consistent with the results of cyclic voltammetry and chronoamperometry. The fact that nickel stimulates cobalt sites to oxidize iron to iron oxyhydroxides at lower overpotential is an important factor contributing to the improved performance of nickel-containing ternary alloy catalysts.