Table 3.

The type and characters of preparation methods of nanomaterials.

Method	Advantages	Disadvantages	Examples
solid phase method	simple synthesis process, high yield, less pollution	uneven distribution of particle size, high agglomeration	ball milling method [21], shear milling method [22]
vapor phase method	high purity powder, small particle size, less agglomeration	high cost, high requirements for instruments	molecular beam epitaxy [23], cathode sputtering [24]
liquid phase method	simple synthesis process, controllable particle size	low distribution, low uniformity	sol-gel method [25], micro-emulsion method [26], hydrothermal method [27]