1. Most research papers indicate to use of (dropwise) HNO3 or HCl with TTIP and Ethanol mixture before adding the leaf extract. Why is it necessary to make the media acidic?
2. During doping of TiO2 with Ag/Cu, do I need to heat up the mixture as well as vigorous stirring? What consequences might I face if I do not choose to heat up the mixture?
1. It is not necessary to make the media acidic. You may also use a base. Acid or base is generally used for the hydrolysis of the TTIP.
2. It depends which method you are going to use for the doping of Ag/Cu into TiO2 lattice. However, heating may significantly affect the homogeneity/in-homogeneity of distribution of doped metal particles and some times crystal structure transformation as well.
Greetings!
1. I agree with Shahid Saqlain, acid or base is needed for the TTIP hydrolysis, but be aware and careful and use protective gear!
2. The most facile way to dope TiO2 with noble metals is the impregnation method. Add the TiO2 to your suspension, the noble metal solution, and the reducing agent, and you stir it for 12 or 24 hours (500-700 rpm), wash it with deionized water or ethanol (you might lose a part of your sample, 5-10% probably). Afterward, you dry the obtained suspension. You should observe a color change (after the 12 or 24 hours, but you might observe this only after the drying process). The plasmonic band can prove the presence of the noble metals in the TiO2 surface - this you can measure with UV-Vis, DRS module.
Dear Fnu Asrafuzzaman thank you for this very interesting technical question. The green synthesis of TiO2 nanoparticles using various plant extracts is certainly a hot topic in current materials science. Very many articles about this topic have already been published in recent years. As mentioned by Shahid Saqlain is not necessary to add any acid to the reaction medium. For example, please have a look at the following relevant article:
Green synthesis of TiO2 nanoparticles from Syzygium cumini extract for photo-catalytic removal of lead (Pb) in explosive industrial wastewater
https://www.degruyter.com/document/doi/10.1515/gps-2020-0018/html
The paper has been published Open Access (see attached pdf file). In this study the authors just used plant extracts to make TiO2 NPs without adding any acid.
For a good overview, please also go through the following very instructive review article entitled:
The current trends in the green syntheses of titanium oxide nanoparticles and their applications
Article The current trends in the green syntheses of titanium oxide ...
This review has been posted on RG as public full text, so it can be freely downloaded as pdf file. Numerous helpful references can also be found and accessed by searching the "Publications" section of RG. For example, just search for the term "green synthesis of TiO2 NPs" and then click on "Publications". This will provide you with a long list of useful papers which have been posted on RG, many of them even as public full texts:
https://www.researchgate.net/search.Search.html?type=publication&query=green%20synthesis%20of%20TiO2%20NPs
Good luck with your research and best wishes, Frank Edelmann
Dear Fnu Asrafuzzaman P.S. For the second part of your question "During doping of TiO2 with Ag/Cu, do I need to heat up the mixture as well as vigorous stirring? What consequences might I face if I do not choose to heat up the mixture?" I would say that if the literature procedure asks for heating up the reaction mixture, you should just do it. A possible consequence of not following the published procedure is that the doping of your TiO2 NPs doesn't work. It just depends on what the authors have found and published. There are procedures in the literature that don't require heating. For example, please have a look at the following interesting RG reference:
Preparation of Ag/Cu-doped titanium (IV) oxide nanoparticles in w/o microemulsion
Article Preparation of Ag/Cu-doped titanium (IV) oxide nanoparticles...
In this study the doping of TiO2 NPs is done at room temperature. I would say that stirring of the reaction mixture is advisable in any case in order to ensure a uniform doping. In this context, please also see the following useful RG link:
Evaluation of the Photocatalytic Activity of Copper Doped TiO2 nanoparticles for the Purification and/or Disinfection of Industrial Effluents
Article Evaluation of the Photocatalytic Activity of Copper Doped Ti...
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