Theoretical Modelling and Facile Synthesis of a Highly Active Boron-Doped Palladium Catalyst for the Oxygen Reduction Reaction

A highly active alternative to Pt electrocatalysts for the oxygen reduction reaction (ORR), which is the cathode-electrode reaction of fuel cells, is sought for higher fuel-cell performance. Our theoretical modelling reveals that B-doped Pd (Pd-B) weakens the absorption of ORR intermediates with nearly optimal binding energy by lowering the barrier associated with O₂dissociation, suggesting Pd-B should be highly active for ORR. In fact, Pd-B, facile synthesized by an electroless deposition process, exhibits 2.2times and 8.8times higher specific activity and 14times and 35times less costly than commercial pure Pd and Pt catalysts, respectively. Another computational result is that the surface core level of Pd is negatively shifted by B doping, as confirmed by XPS, and implies that filling the density of states related to the anti-bonding of oxygen to Pd surfaces with excess electrons from B doping, weakens the O bonding to Pd and boosts the catalytic activity. Better with a B in its bonnet: Theoretical modelling shows that B doping negatively shifts the surface core level of Pd and lowers the barrier to O₂dissociation for the oxygen reduction reaction (ORR). A B-doped Pd nanoparticle catalyst was then rationally designed, synthesized in a facile manner by electroless deposition, and shown to be a highly active ORR catalyst compared to commercial Pd and Pt catalysts.