Effect of Oxygen Reduction Reaction on Pt/Pd3Fe (111) Alloy Electrocatalyst: A DFT Study

The development of efficient oxygen reduction reaction (ORR) catalysts has been comprehensively studied aiming at decreasing cathode platinum loading without loss of efficiency. We have systematically examined the effect of activity and stability of a Pd3Fe (111)-supported platinum monolayer as ORR catalyst within the framework of density-functional theory (DFT). It has been found that the ORR mediators weakly bind to the Pt/Pd3Fe (111) surface due to being alloyed with oxygen. The ORR mechanism is predicted to be OOH dissociation considering the ORR elemental steps. The rate-determining step refers to the OOH dissociation with a reaction barrier of 0.21 eV, highlighting a superior catalytic efficiency. A shift in electrochemical potential of platinum surface dissolution on the Pt/Pd3Fe (111) surface has also been evaluated to investigate the stability of Pt/Pd3Fe (111) electrocatalyst. Results verify the enhanced stability of the Pt/Pd3Fe (111) surface against surface dissolution and oxidation of platinum compared to the oxidation surface of platinum (111). The improved activity, along with its increased stability, makes the new ternary alloy electrocatalyst an ideal option for the development of new cathode catalysts for fuel cell applications.