I have prepared naked silver nanoparticles by using sodium borohydride reductant. I have dried the sol in oven but the dried particles were like a dot on glass vial and yield was too low. I have also centrifuged the solution at 5000 rpm for 20 min but get nothing. Please guide, how can i get the powdered form for XRD and SEM.
I'll be very thankful in this regard.
Ibrahim Akram Once they’re in powder form then they are no longer ‘nano’. There are no free, discrete, independent particles < 100 nm in a powder. Keep the material in colloidal form if you want to preserve the properties.
You need very little material for SEM but it will show agglomerates and aggregates and not the material you have prepared in colloidal suspension. Similarly for XRD (if you have enough) where you'll be able to get information on phase(s) and, hopefully, some estimate of crystallite size based on the Scherrer or Williamson-Hall equations.
Ibrahim Akram One route forward could be to absorb your Ag colloid onto an 'inert' substrate such as silica (Aerosil 200, for example). This can lead to your nanoparticles being sterically stabilized on the substrate and, thus, separate and discrete.
Buchi makes lab sized spray dryers with electrostatic collectors.
https://www.buchi.com/en/products/instruments/nano-spray-dryer-b-90-hp
By the way, there are no nanoparticle solutions
https://drive.google.com/file/d/1z7nM0U8vOJ2uKuoDGIZyf07WnWK8xOUo/view?usp=drive_link
Ibrahim Akram BTW, in the presence of water or oxygen, you do not have 'naked' or 'bare' Ag (nano)particles. The surface (top 5 or 10 atomic layers) is fully oxidized and silver is in the Ag+ (monovalent) state and not as Ag0 (metal). ESCA/XPS easily shows this. And incidentally, it's Ag+ that's the bactericide not Ag metal. For more information, take a look at this webinar (free registration required):
Silver colloids and invisible ink
https://www.malvernpanalytical.com/en/learn/events-and-training/webinars/W150902SilverColloidInvisibleInk.html
You'll also have intractable B as a contaminant in your Ag which cannot be removed. This is why I avoided borohydride reduction in my Ph.D and used dilute hydrazine hydrate (5 or 10%) instead - the only products being N2 and water.
- Hello Sir Alan F Rawle I want to characterized the AgNP, after I did the purification by centrifugation and washed it with the distilled water, should I air dryed them overnight then before doing the characterization with instrument ?
Michelle Darmawan as you can learn from the answers given so far, you have to characterize them in aqueous dispersion, not after drying.
Titus Sobisch Thank You for your answer Sir..
I really confused because of many papers I've come across do not specify how they characterized the AgNP and I've received a recommendation to air dry them instead of using an oven..
I'm wondering if I should opt for TEM instead of SEM, as SEM typically requires the sample to be in powder form?