I think you should consider to try ball mill method

:)

coating of ZnO nanoparticles by thermal evaporation technique on CNTs.

you can use physical methods instead of chemical such as thermal evaporation, R F Sputtering etc.

thank you for you answers, shama Parveen please if you have any paper about the thermal method?

if you mean using ZnO as supported for the prepare CNTs ?because we cant deposited ZnO on the CNTs it is impossible. 

Dear Ahmad.

you can use,  zinc acetate [Zn(CH3OO)2.2H2O] + ammonium hydroxide (NH4OH) for  formation of ZnO on CNTs

For more details, please go to my paper; Development and biomedical application of nanocomposites: in situ fabrication of ZnO-PbO nanocomposite through microwave method