I am working on Fabrication of SnO2-Graphene Nanocomposites to study their dielectric properties and for applications in supercapacitors. Being Physics student I am not good at Chemistry. I adopted following method for SnO2 Nanoparticles to use them for composites fabrication. But I am much confused and want to know the basic chemistry of every chemical being used in the following reaction. The method is mentioned below:
For 0.1M solution, 3.50 gm of Tin Tetra Chloride (SnCl4.5H2O) was added in 100 ml ethanol in a beaker.
The solution was set at stirring for 10 min on magnetic stirrer at 100 C at the rate of 550 rpm. 2ml acetic acid was then added drop by drop.
After which, 5ml ammonia solution (NH4OH) was added drop by drop in the solution to increase the pH value of the solution which results in nucleation (the basic phenomena of precipitate formation in chemical co precipitation). When pH value reached at 5, precipitates were found in the solution and its colour become white. The value of pH was set at 5 and the solution was left on stirring for 1 hour at 550 rpm at 100 C◦.
After 1 hour, the solution was aged at room temperature for 1 hour. Then it was centrifuged and washed with distilled water 3 times. The centrifugation rate was 3000 rpm and time was 3 minutes each time. Then the solution was kept in an oven for drying overnight at 80 C◦. Next day the dried product is grinded in powder form. Grinded powder then kept in furnace at 600C for 5 hours.
Hi Muhhamad,
It seems, Acetic acid to disolve SnCl2 in ethanol, since it is a bit hard to dissolve. Basic media (NH4OH) to get a tin hidroxide (or an oxo-hydrous stannic ones) which precipitate and you can extract by centrifugation due to lower solubility... this is the white colour
600 C (I think in air atmosphere) to produce tin oxide
It helps?. Solubility phases diagrams (analitical chemistry) for SnCl2 can explain more extensive than me
No now, Muhhamad, call me José, please. I must find where they are. Ks for Sn(OH)2, solubility for SnCl2... I will search. Surely they are in analytical Chemistry books, if not, just with parameters (Ks vs pH, for instance) get an approximation.
For deep analysis, Library is hard but helpful.
If I have more news, I send a message
Thanks.
I am synthesizing these NP's to use them for fabrication of Graphene based SnO2 Nanocomposites. The quantity I will obtained by above mentioned concentrations will be less for further work and characterization. I need nanoparticles in large quantity.
If I repeat the above method suppose 3 times, I will most probably could not get SnO2 Nanoparticles of same size, shape etc due to minor changes in temperature, rate of reaction or time of stirring.
So, if I multiply the above mentioned concentrations of precursor and other chemicals by 3 and follow the same procedure, do you think there will be some changes in nanoparticles due to large quantity as compared to those nanoparticles by above mentioned concentrations?
Hi Muhammad, sometimes wiki helps a bit faster.
"Tin(II) chloride can dissolve in less than its own mass of water without apparent decomposition, but as the solution is diluted hydrolysis occurs to form an insoluble basic salt:
SnCl2 (aq) + H2O (l) is in equilibrium with Sn(OH)Cl (s) + HCl (aq)
Therefore if clear solutions of tin(II) chloride are to be used, it must be dissolved in hydrochloric acid (typically of the same or greater molarity as the stannous chloride) to maintain the equilibrium towards the left-hand side (using Le Chatelier's principle).
Solutions of SnCl2 are also unstable towards oxidation by the air:
6 SnCl2 (aq) + O2 (g) + 2 H2O (l) --> 2 SnCl4 (aq) + 4 Sn(OH)Cl (s) "
Read from the end, and change direction. equilibrium is equilibrium
So, thats mean as I understand. SnCl4 solved in ethanol and acetic acid decompose to SnCl2 and produce the tin oxyclhoride (before I was wrong, is not tin oxohydroxide). NH4OH in sense of neutralize chloride ions and get Sn(OH)2 white precipitate... actually the oxyclhoride is also white.
When Sn(OH)2 is centrifugate, whasing several times to release chloride ions and 600 C is for turn to SnO2,
Second question, if multiply by 3 you get 3 times amount... good question for a chemist. My answer: sometimes yes, sometimes no, sorry.
Then, try this:first if you have a pHmeter will be nice. Made same synthesis take note of pH in each step. Since is a 100 C, extract few mL in a beaker and check pH. Has pHmeter which work with temperature, but I am not sure their accuracy. After:
10.5 g SnCl4 in 400 mL ethanol
stirring at same rpm and add acetic acid to reach the same pH than your previous experiment. Here does not work add 6 mL (2*3) works by pH.
Same for ammonia, add till reach good pH
time for stirring, temperature, and others parameters no modify in time. I mean, 1 hr or 1.5hr does not matter, 550 or 600 rpm, neither. It seems a reaction pH sensitive.
And where water comes? Ethanol (96%) I guess, NH4OH 30% (NH3+H2O), SnCl4*5H2O (crystalization water in estructure), and acetic acid... maybe not
Probably get a bit higher particles (no huges ones) but in the same magnitude order and useful.
I hope it help
Regards
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