Figure 3: SEM and TEM characterization of RuCo@NC hybrid.

(a,b) The FESEM and TEM images of S-4. Scale bars, 100 nm. (c–e) HRTEM images of S-4. Scale bars, 10 nm. (f–j) HAADF-STEM image and corresponding EDX maps of S-4 for Co (g), Ru (h), C (i) and N (j), respectively. Scale bars, 20 nm.