Fig. 1From: Fe, N, S-codoped carbon frameworks derived from nanocrystal superlattices towards enhanced oxygen reduction activitya TEM image of monodispersed Fe3O4 nanocrystals and size distribution analysis (insert). b SEM image of ordered Fe3O4 superlattices via drying-induced self-assembly. c TEM image of ordered carbon frameworks after repeated acid treatment. d HRTEM image of Fe/CFs which illustrates the ultrathin interconnected spherical pore wallsBack to article page