I would like to examine the stability of my electrocatalyst within the potential range between 0.0 and 1.6 V (vs. NHE).
I will use 3 electrode system (Pt plate for CE, Ag/AgCl for RE) and 0.1 M HClO4 as an electrolyte.
On top of the experiment, I guess the oxidation of water at above the potential of 1.2 (vs. NHE) must be occurred, which can lead to get wrong CV data due to the overlapped currents obtained from water oxidation and Pt redox reaction.
I have read many papers related to examine the stability of Pt nanoparticles as an electrocatalyst in harsh condition such as 0.4~1.4 V (vs. NHE) and so on. I want to know how it was possible to examine only the performance of Pt electrocatalyst except the effect of water splitting.
Water splitting is definitely bound to occur in aqueous solutions. Considering the fact that you are using Pt along with a wide potential window, I do not think there is any way possible to avoid it. Considering you are using HClO4 at this potential window, you may also end up with some degree of chlorine evolution. The only way possible to avoid water splitting is to carry out your tests in dry organic conditions (say Dry acetonitrile with dry TBAP was your supporting electrolyte), if the purpose of your study allows you to.
Hello David,
If I understand correctly, you have to perform the experiments in aqueous solution. Simply put, what you will observe is whether your electrode or water oxidize first, at potentials higher than the Nernst potential for the O2/H2O couple. Since Pt has certain activity for this reaction, it is in practice impossible to separate Pt oxidation from H2O oxidation. If you work in aprotic media, you will not be testing the electrode stability in the proper conditions, it seems to me. That's the point of the experiment: to test it in conditions as close as possible to real systems.
In acidic electrolyte, Pt corrosion occurs concomitant to O2 evolution, because Pt is not a very good catalyst for this reaction. You can't really separate both processes. A way of calculating the contribution of each reaction could be measuring the amount of evolved O2 and compare the corresponding charge with the experimental integrated charge, let's say operating at constant potential for some time.
I'm afraid Arun and Antonio are right (except for chlorine evolution). In fact you have O2 evolution because your catalist is at work!
I am agree with Antonio: your chance is measure the oxygen evolution and cross finger...
Hello David. If your goal is to examine Pt durability then Anna's last paragraph is the direction to go. Good luck!
David,
if the most important for you is the stability of the nano-catalyst, then you can do the following experiment, following Topics in Catalysis 57.1-4 (2014): 255-264:
1) record a blank cv of your catalyst in H2SO4. The hydrogen/sulphate region will give you the best resolution in different crystallographic facets of your nanocatalyst. This will allow you to characterize the active sites of your catalyst, as well as total surface area (if you integrate the CV in the hydrogen region).
2) Wash the electrode. Do your catalysis runs in perchloric.
3) Wash the electrode and record a blank in sulphuric again. It will immediately tell you what has changed (area, shape, active sites) of your platinum.
See here: doi:10.1016/j.electacta.2013.01.056
NB: do not exceed 0.8V vs NHE when recording the blank cv's!
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