Transition Metal Decorated Graphyne: An Efficient Catalyst for Oxygen Reduction Reaction

The sluggish kinetics of oxygen reduction reaction at the cathode of the fuel cell is found to be one of the limiting factors in fuel cell technology. The conventional platinum based catalysts make the fuel cell more expensive because of its limited availability and high cost. In the present study, we have explored transition metal decorated graphyne as an alternate catalyst for oxygen reduction. The metal (Fe, Co, and Ni) binding energies over the graphyne surface are found to be higher than the corresponding metal cohesive energies. Iron and cobalt decorated graphyne are found to be more reactive toward oxygen adsorption, whereas the nickel decorated system is inactive. In acid medium, both iron and cobalt decorated systems are observed to follow a more efficient four electron reduction path. In alkaline medium, the reduction on iron decorated system is through a four electron reduction path, while in cobalt system it is through a two-electron reduction path with the formation of hydroperoxide anion. The free energy profiles show that these systems are more efficient as catalyst for oxygen reduction in alkaline medium as compared to acid medium.