Density Functional Theory Study of Iron Phthalocyanine Porous Layer Deposited on Graphene Substrate: A Pt-Free Electrocatalyst for Hydrogen Fuel Cells

This paper details the use of ab initio density functional theory (DFT) to analyze a potential Pt-free catalyst, nonbonded iron phthalocyanine monolayer on graphene substrate (FePc/graphene), for an approximation of catalytic pathway and properties in oxidation reduction reaction of H-2 and O-2 to produce water. DFT calculations show that the associative mechanism, where O-2 molecules chemisorbed on Fe site and prefer hydrogenation to O-OH intermediate species with ambient H+ and electron transfer followed by subsequent water formation reaction (WFR), is found to dominate for the FePc/graphene surface. Throughout the entire oxygen reduction reaction (ORR) process, the initial reduction of O-2 to O-OH reaction appears to be the rate-limiting step with a reaction barrier of 0.68 eV. The complete free energy profile suggests that oxygen molecules are inherently favorable for reduction into water on FePc functionalized graphene surface.