Coating layer-free synthesis of sub-4 nm ordered intermetallic L10-PtCo catalyst for the oxygen reduction reaction

The ordered intermetallic PtM alloys with L10 structure are considered as the most promising oxygen reduction reaction (ORR) catalysts owing to the strong chemical bond between Pt and M atoms effectively suppresses the leaching of M atoms. However, the preparation of ultrafine L10-PtM alloy nanoparticles with high ordering degree is still a challenge because the nanoparticles tend to agglomerate during high-temperature annealing. Herein, we propose a coating layer-free strategy to controllably synthesize sub-4 nm highly ordered intermetallic L10-PtCo catalyst. The strong interaction between N-doped carbon (NC) and PtCo(OH)x effectually inhibits the agglomeration of nanoparticles during thermal treatment, while the O vacancies generated by the thermal decomposition of PtCo(OH)x are beneficial to prepare the highly ordered intermetallic L10-PtCo alloy. The as-obtained L10-PtCo/NC alloy catalyst shows excellent ORR activity in both half-cell and single cell tests, which is much better than that of disordered A1-PtCo/NC and commercial Pt/C catalysts. This work provides a facile and efficient method for fabricating the ordered intermetallic L10-PtM alloy catalysts with high ordering degree.