Fig. 1. TEM and SAED characterizations of the PC-1 structure. (a) TEM image at low magnification. (b) STEM image. (c) A typical SAED pattern of a single PC particle. The patterns correspond well with that of the NiS₂ pyrite crystal. (d) A typical HRTEM image of a single PC particle. (e) HRTEM image at higher magnification. The area between the red lines showcases the amorphous shell at the periphery of the particle. (f) The FFT pattern of the entire particle in (d).