This is a nanochemistry lab I developed for my Junior and Senior level Inorganic Chemistry course. I am NOT a nano/matertials person, but I know how important nanochemistry is and I wanted to make something where students could get an interesting introduction to the area. The first time I ran this lab was also the first time I made gold nanoparticles ever!
We do not have any surface/nano instrumentation here (AFM, SEM/TEM, DLS, etc... we can access them at other universities off-campus but that takes time and scheduling), so that was a key limitation in making this lab.
While it was made for an upper-division course, I think It could be adapted and implemented at many levels, including gen chem. I do not spend much time on nano in the lecture (none in fact), so this lab was made to have students learn a bit about nanochemistry somewhere in inorganic chemistry. We have one 10-week quarter of inorganic lecture and lab, offered every spring quarter.
This lab takes approximately 2-3 hours if students are well prepared and using their time well, but is usually spread over 2 days. Students are concurrently doing experiments for another lab or two because we have a lab schedule that overlaps multiple labs, and can do these during one day or across two days. The lab space is an organic chemistry laboratory, so we have access to the usual lab synthetic equipment
Students in thelaboratory write lab reports,which are the due the week after the last day of the lab experiment. In the lab report they use their UV-Vis data to calculate information about the AuNP.
The lab has been posted, as well two photos from students' ferrofluids (these were posted with permission on our departmental blog). A rubric has been posted as a faculty-only file. I have also included a student submission that received over 90% on the lab with their identifying information removed. Students write and introduction and need to cite journal articles in their report, so they are expected to do reading on nanochemistry topics outside of the lab period as they write their reports.
I am sure the lab can be improved, this was what i came up with the materials and time I had. I plan on continuing to revise and edit it as time goes on. Any suggestions are very welcome!
A student should be able to perform a chemical laboratory experiment safely and follow proper lab notebook protocol.
A student should be able to determine the average size of AuNPs from spectroscopic data and primary literature.
A student should determine atomic and nano-scale information from physical properties.
A student should be able to construct a lab report in the style of an ACS article (Students in my lab wrote lab reports for each experiment).
For this experiment, you need
The chemical materials - HAuCl4, trisodium citrate,
UV-Vis spectrometer (mainly Vis)
A laser pointer
Strong magnets (the stronger and larger the better)
The syntheses are relatively straightforward, although we've had some problems getting "spikes" for the ferrofluid. Anecdotally, adding the reagents and doing the steps faster tends to give better "spiking". Some students just see a blob moving around in response to the magnet, which was fine in terms of their report.
The AuNP synthesis can also be done with an ultrasonicator or by addition of sodium borohydride, among other methods. We don't have them make a calibration curve of chloride addition, but that could be a possibility.
I like having a pre-made solution of a red oroganic dye to shine the laser pointer through to compare versus the laser shining through the AuNP solution.
One year, the AuNP synthesis was going very slow. We realized it was because the Au(III) was diluted in acid, so it was protonating the citrate. Boiling for a while before adding the citrate solution helped fix this problem.
KAuCl3 is also a good source of Au(III) for this lab.
Students are evaluated on their participation in lab, lab safety, lab notebook pages, and a lab report turned in a week after the last day of the experiment.
This lab was first run in spring of 2016, and again in spring of 2017 and 2018 (a different instructor carried out the lab in 2018).
In general, students do well on the lab report and seem to enjoy the experiment.They often need guidance when interpreting the Analytical Chemistry article and selecting the correct equations. Discussing their values with them in office hours ("does that make sense?") helps them understand their calculations.
A sample lab report that scored above 90% is included in the faculty-only files.