Coupling fine Pt nanoparticles and Co-N_x moiety as a synergistic bi-active site catalyst for oxygen reduction reaction in acid media

Fabricating high-efficiency catalysts of Pt nanoparticles coupled with single-atom sites (M[sbnd]N[sbnd]C) attracts intensive attention to accelerate the oxygen reduction reaction (ORR). Here we rationally design the low-Pt hybrid catalyst containing fine Pt nanoparticles coupled with Co-N_x moieties via a microwave-assisted heating process. The well-dispersed Pt nanoparticles are anchored by Co[sbnd]N[sbnd]C supports because of the metal-support interaction. Furthermore, the Co-N_x moiety acts as an electron donor to regulate the electronic structure of Pt through the electron synergistic effect, moderating the adsorption energy of oxygen intermediates on Pt sites, and then increasing the intrinsic activity of Pt. In addition, the overflow effect from Co[sbnd]N[sbnd]C to Pt facilitates a nearly four-electron process and enhances the kinetics of ORR. In acid media, the optimized 10% Pt/Co[sbnd]N[sbnd]C hybrid catalysts with Pt nanoparticles size (2.18 nm) exhibit improved ORR activity and robust durability, delivering a half-wave potential (E_1/2) of 0.886 V and negligible loss after accelerated durability test, exceeding the best-in-class commercial Pt/C. The finding of the synergy between Co[sbnd]N[sbnd]C supports and Pt nanoparticles offers a novel ideation to construct various low-loading Pt-based hybrid catalysts.