Yes you can prepare nano particles even at room temperature.Mix grounded plant extract thoroughly with ZnO precursor. Heat produced while stirring the solution is sufficient. But size of the nano particle depends on the type of plant extract which you have used. Better to follow the article attached below.

All the best.

Green Synthesis of Zinc Oxide Nanostructures

By Tuğba Isık, Mohamed Elhousseini Hilal and Nesrin Horzum

DOI: 10.5772/intechopen.83338 .

Thanks madam Sharmila Rudramamba

Mohammed Almutairi

There are a couple of things in your post that concern me:

• 1 M (= 1 molar) implies a solution and not a powder
• 'Nanopowder' is an oxymoron considering that there are no free, independent, discrete particles < 100 nm in a powder. See (for example):

May 28th, 2019 Dispersion and nanotechnology https://tinyurl.com/y2wfzed7

November 3rd, 2015 Adhesion and cohesion http://tinyurl.com/zwb2wlh

• ZnO will partially hydrolyze in water forming Zn(OH)2. Are you going to prepare the system in a non-aqueous environment? Then I have questions about the plant extract...
• Which plant extract contains a source of zinc? Or (as I suspect) you're trying to reduce a zinc salt (which one?) to ZnO.
• How do you believe you can make ZnO without a heating step?

If your material has an SSA > 60 m2/g (for unit density) then you could consider it 'nano'.

Sharmila Rudramamba

Please explain the chemical reaction(s) in your 'synthesis'.

Sharmila Rudramamba I'm confused.. if the authors of the chapter you provided used a salt (Zn (II)), and the final oxide also has Zn (II), what oxidation and reduction are those leaf extracts promoting?

I didn't get the role of those extracts, seems to be just regular precipitation.

Thermogenic plant extract like Amorphophallus paeoniifolius can generate heat it seems.

Alan F Rawle thanks

that‘s right it must be solution not a powder.

I mean synthesis ZnO by using plant extrac. I was tried to reduce zinc salt to ZnO.

ZnO might be make without heat by adding wise drops of NaOH to set the pH of the solution to 7.

Regards