fig4

Figure 4. (A) Scheme of Ni-based sulfide; (B) XRD, SEM, TEM and HAADF-STEM image of Ni₃S₂@Ni₃P and line scanning profile of NI₃S₂@Ni₃P; (C) Confirm the performance and valence state of Ni, S and P^[104]. This figure is quoted with permission from Guo et al. XRD: X-ray diffraction; SEM: scanning electron microscopy; TEM: transmission electron microscopy; HAADF-STEM: high-angle annular dark-field scanning transmission electron microscopy.