maybe use some amphiphilic molecule as template to desire form. Like CTAB or other surfactant molecules in micellar synthetic route

I found a good review about nanocrystals synthesis : Microwave-Assisted Synthesis of Colloidal Inorganic Nanocrystals. Mostafa Baghbanzadeh, Luigi Carbone, P. Davide Cozzoli,* and C. Oliver Kappe*

You shoudn't use CTAB for nanorod synthesis because CTAB normally very toxic. If you study toxicology of nanomaterials, then this process can wrong to you. You can try another surfactant such as PEG because it is more peacefull than CTAB