Fig. 2.

Schematic demonstration of novel YS structure of: a polystyrene spheres (PS)@NiCo₂S₄. Reprinted with permission from Ref. [71]; b urchin-like Bi₂S₃@polypyrrole(ppy). Reprinted with permission from Ref. [72]; c rough VO₂ microspheres. Reprinted with permission from Ref. [73]; and d pomegranate-like Si@C. Reprinted with permission from Ref. [75]. The corresponding TEM images of e PS@NiCo₂S₄, and f Bi₂S₃@ppy. Reprinted with permission from Ref. [71, 72]. g₁ FESEM and g₂ TEM images of VO₂ microspheres. Reprinted with permission from Ref. [73]. h SEM image of pomegranate-like Si@C particles. Inset shows the spherical morphology in overall. i Details of sub-YS nanospheres in a single pomegranate-like Si@C particle. Reprinted with permission from Ref. [75]