I follow the literature to synthesize Ag nanoparticles, but I can't get the same result. I think the problem is that when should adjust pH?
Dear Sir. Concerning your issue about the synthesis of 10nm Ag nanoparticles. Most reported examples of Ag nanoparticles obtained by chemical reduction are performed in aqueous media. A post-synthesis transfer to an organic solvent is usually difficult due to aggregation processes. Nevertheless, the synthesis of metal nanoparticles in organic solvents has some advantages such as high yield and narrower size distribution, with the additional advantage that in some cases the solvent itself can act as reducing agent to obtain Ag nanoparticles. For example, Pastoriza-Santos and Liz-Marzan proposed a synthetic route to obtain Ag nanoparticles spheres (≈6–20 nm) from the spontaneous reduction of silver. I think the following below links and the attached files may help you in your analysis:
http://pubs.rsc.org/en/content/articlepdf/2014/RA/C3RA44507K
http://pubs.rsc.org/en/content/articlepdf/2014/RA/C3RA44507K
Thanks
See:
September 2nd, 2015 Silver colloids and invisible ink
https://www.brainshark.com/malvern/vu?pi=560497681&b=1&tx=120486&c1=22
February 18th, 2016 Metal colloids - their preparation, application, and characterization
https://www.brainshark.com/malvern/vu?pi=529368070&b=1&tx=120486&c1=22
Small size is favored by low concentration of AgNO3. The usual precursor is the diammine salt and this controls the pH to medium alkaline. A reducing agent such as hydrazine hydrate in 1 - 5% concentration or hydrogen avoids contamination with other elements such as B (from NaBH4 reduction). Stabilization at probably 100 mV zeta potential and above required for 10 nm particles. Steric stabilization is generally more successful but a 50 kDa PEG or PEI adds considerably to the size of the particle. Citrate reduction is also appropriate especially for Au (I've never tried it for Ag) and the citrate ion can stabilize the system. Remember that the surface of the 'silver' colloid is actually oxide - Ag in the +1 oxidation state.
@Nurul You should post a separate question to avoid confusion.
For a polydisperse distribution, DLS provides an intensity distribution which will always be larger than the number distribution provided by electron microscopy. So it is quite conceivable that a 234 nm z-average may have a size < 100 nm under TEM. Take a look at:
http://www.materials-talks.com/blog/2017/01/23/intensity-volume-number-which-size-is-correct/
It is worth carrying out a Stokes' Law calculation for Ag particles of 234 nm and less - for the density, settling is likely, and this is another indicator of the size if it's happening. If your particles are genuinely 10 nm Ag then the colloidal suspension will be clear and colored (the color depending on the size). Any turbidity or settling indicates particles >> 100 nm.
- Badges
- Science topic
- Similar topics
- Chemistry
- Nanotechnology
- Nanostructured Materials
- Nanoparticles