Can anyone understand the preparation steps here? I can't understand and reappear! I want to use this method and make nanoparticles based on my template method.
Yifan Zyf Have you tried reproducing their method? What aspects do you not understand? Seems like just dipping clean steel/iron sheets into a solution of copper sulfate and then allowing the double decomposition to deposit copper:
Fe + Cu2+ → Fe2+ + Cu
The (loosely adhering) copper is then scraped off the steel plate and found to be ‘nano’. From the comment 'The copper on the substrate was separated with a polymer blade and kept in the preservative solvent of ethanol to prevent oxidation', I will assume that, with the density of copper (~ 9.3 g/cm3) that the material will sit rigidly on the bottom of the container... This will also not prevent oxidation (ethanol contains O...).
Obviously, it’s a collection of fused particles (electron microscopy shows this) but the crystallite size is in the nano region from the Scherrer equation. There are no free, discrete, independent particles < 100 nm in the system.
You could always try contacting one of the authors directly especially as it's a fairly recent paper.
Yifan Zyf OK, your needs are totally different to what I understood from your initial question. There’s a world of difference between steel plates in copper sulfate to an optical adhesive. I am familiar with the Norland NOR-61 product having used it as a UV-curable glass adhesive back in the 1980’s. OK, we also know that silver salts can be easily reduced to silver metal by UV/visible light as well as heat or mild reducing agents. I think that this would be the easiest system to deal with. Far easier than MnO2 or ZIF-8. Two routes suggest themselves and I prefer the latter below. Note that handling of the silver salts should be undertaken in the absence of light typically by covering beakers, flasks etc with aluminum foil to prevent premature decomposition. A low loading of Ag in your final system will be easiest to deal with and preferable.
• Find a solvent which will dissolve both the NOR-61 product and an appropriate silver precursor (the silver diamine complex is generally preferred for pH control). Of course, water is not a possibility here. AgNO3 is soluble to differing degrees in a number of organic solvents as are salts such as silver acetate. Take care with solvents such as the volatile methylene chloride or the poisonous acetonitrile. Methylene chloride suggests itself only because it’s used as the basis to separate already bonded glass: https://www.norlandprod.com/techrpts/separating.html and ammonia can be incorporated into the system. You could then combine the silver salt (could be acetate alternatively) in the organic solvent with the NOR-61 adhesive in the same solvent. You’d then have a homogeneous liquid that you could spread (or spin) onto a glass substate (for example), evaporating the solvent, and use UV light both to cure the adhesive and simultaneously reduce the silver precursor. Hydrogen gas would be another possible reducing agent
• I think that this may be a better route using a third material such as fumed silica, SiO2. Here we’d incorporate the silver salt (in organic solvent) by absorbing it onto the silica (similar to making a supported metal catalyst). This silica could then be mixed with a spatula into the NOR-61 adhesive. This system could then be screen printed or via a doctor blade onto glass for example. Reduction by UV light, heat or hydrogen could then take place as before. Of course, UV light will cure the adhesive too
I'd initially aim for a final Ag concentration at say 0.5 - 1wt% and use the reagents appropriately.
Yifan Zyf For a primer on silver 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
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