Synergetic Effect between Platinum Nanoparticles and Single Atoms Revealed in the Catalytic Mechanism of Traditional Pt/C for the Oxygen Reduction Reaction

Traditional Pt/C is the most classic electrocatalyst for the oxygen reduction reaction (ORR) in fuel cells, in which the ORR mechanism is generally understood based on Pt nanoparticles alone. Here, based on the revealed fact of the inevitable coexistence of Pt nanoparticles and single atoms on such Pt/C, via density functional theoretical calculation, the pathways for the ORR process have been revealed: besides the known pathways on isolated Pt nanoparticles and single atoms, the other two pathways with enhanced ORR performance occur on neighboring Pt nanoparticles and single atoms due to their unique synergetic effects with the enhanced four-electron pathway by decreasing the H2O2 yield. Inspired by such insights, the mass ratio between Pt nanoparticles and single atoms was optimized to maximize their synergetic effect, which yielded an optimal hybrid Pt/C with Pt 8.0 wt % (5 wt % Pt SAs with 3 wt % Pt NPs). This mixture exhibited remarkable ORR performance on the same level as Pt/C with Pt 20 wt %, achieving a huge enhancement in Pt utilization. Such work deepens the understanding of the catalytic ORR mechanism of traditional Pt/C and can guide the design of Pt- or other precious-metal-based nanocatalysts with a high performance/price ratio for all kinds of energy processes.