I think you should apply another method for the synthesis of zinc nanorods-

Citric acid (2.58 g) dissolved in 2.7 mL of ethylene glycol was mixed with zinc nitrate solution (3.6558 g dissolved in 10 ml of HNO3) and vigorously stirred for 30 min to obtain a clear solution. Then, the solution was allowed to heating around 90°C with constant stirring for 2 h resulting in the formation of gel without any precipitation. The formed gel was further heated up to 150°C in order to get a dried gel. During this process, the product expanded three or four times the original volume resulting in bread like voluminous material. The resulting powder was allowed to calcine at 500°C in a vertical tube furnace for 2 h under flowing air. Finally, white-colored ZnO nanorods were obtained and stored in vacuum.

See the attachment.

Probably you can try same procedure with hydrothermal method.

It is an excellent question and i am happy to answer this question. If you want to grow ZnO Nanorods arrays on any substrates you should have done two steps. First step: You can make solution in deionized water for equimolar concetration of zinc nacetate dihydrate and monoethanolamine (Zinc Ace:MEA=1/1). Then the can stirrer at a temperature of 70 deg for 1 hour . After that the solution can stirrer at room temperature overnight. Then the solution can be used for making a thin film by sping coating method. Second step: You can make a mixture of zinc nitrate dihydrate and HMTA of 25mM in deionised water and stirrar at RT for 20 min. No need to add any chemicals and no need to make transparent solution. After stirring, the ZnO seed layer substrate can dip vertically in the solution and keep it in any constnat temperature (60-95)deg system ( Auto cleave, hot plate) for 15 min to few hours. After completing induction time the subtratre can take out from the solution and can was DI water for several times and dry it by gently N2 flow. I have done many works regarding ton this field and I am sure that you have no need to make any transparent soltion. This process is very simple and low cost. I hope you will success and will get excellent orientation of ZnO NR arrays.

Dear Md. Kamruzzaman ,

Thanks for your reply. I will follow your steps and get back to you for any doubt.

Can i use Diethanolamine instead of monoethanolamine in first step ?

Dear Shounak,

Yes, you can use Diethanolamine instead of monoethanolamine in the first step for solgel solution.

Dear Md. Kamruzzaman ,

Could you plz elaborate the spin coating technique step (protocol) and also, does a step of final annealing of 500 degree required after step 2.

Plz kindly clarify.

Dear Shounak,

You can use 2000-3000rpm to deposit thin seed layer and finally you no need to anneal at 500 deg. 250-450 deg is ok for final annealing.

Dear Md. Kamruzzaman ,

after doing first step, some white color material (small amount) in sticking at the bottom of the beaker.

Plz suggest me how to clean it. I have got transparent sol after adding Diethanolamine . I have prepared 0.3M Zinc acetate dihydrate seed solution with 2-methoxy ethanol .

hope to hear from you.