Reconstructing the Coordination Environment of Platinum Single-Atom Active Sites for Boosting Oxygen Reduction Reaction

Exploring highly efficient platinum single-atom (Pt1) catalysts for oxygen reduction reaction (ORR) is desired to greatly reduce the catalysts costs of polymer electrolyte membrane (PEM) fuel cells. Herein, based on a nitrogen-doped active carbon (N-doped Black Pearl, NBP), an atomically dispersed Pt-based electrocatalyst is first prepared via a hydrothermal ethanol reduction method with Pt content of about 5 wt % (Pt1/NBP), and it shows high selectivity for the two-electron oxygen reduction pathway. Through further high-temperature pyrolysis, the coordination environment of these isolated Pt atoms is reconstructed to form uniquely nitrogen-anchored platinum single-atom active sites (Pt1@Pt/NBP) for a highly efficient four-electron oxygen reduction pathway. The obtained Pt1@Pt/NBP catalyst presents excellent ORR performance and stability as well as fast ORR kinetics at a high potential region. As a cathode catalyst of a PEM fuel cell, Pt1@Pt/NBP demonstrates 8.7 times higher mass activity than the commercial Pt/C at a cell voltage of 0.9 V.