fig2
Figure 2. (A) Schematics of heterogeneous electrocatalysts showing coexistence of Pt-Co NPs, Co@graphene, and Co-N4-C PGM-free active sites (named LP@PF)[39]; (B) HAADF-STEM image of Pt-Co NPs in the heterogeneous electrocatalysts[39]; (C) HAADF-STEM image of PGM-free support containing atomically dispersed Co (circled in red) and trace Pt (circled in blue)[39]; (D) Schematic illustration for Preparing closely packed Pt-based alloy nanocrystals and dense isolated Ni sites hybrid (Pt1.5Ni1-x/Ni-N-C)[40]; (E-G) HAADF-STEM images of Fe-Co dual sites embedded on N-doped porous carbon [(Fe, Co)/N-C][45]; (H) Schematic for well-dispersed Ta-TiOxnanoparticles on the carbon substrate as scavengers[49]; (I) Decay kinetics of the OH-DMPO·as a function of time with and without the addition of Ta-TiOx/KB (the supported Ta-TiOx nanoparticles on a Ketjenblack substrate)[49]; (J) Cell voltage and power density polarization (K) for Fe-N-C with and without the addition of Ta-TiOx/KB before and after the accelerated durability test (ADT)[49]. PGM: Platinum-group metal; NPs: nanoparticles; HAADF-STEM: high-angle annular dark-field scanning transmission electron microscopy.
