Hello scholars,
Recently, I have been working on AOR. I have obtained interesting results, however, the result is a bit disturbing as it comes with noise in the curve. Below is a picture of such. I have read up some of the suggestions presented to similar circumstances in RDE measurement for ORR. I have not been able to overcome the challenge. For my circumstance, am working using Pt wire/coil as counter, Ag/AgCl as reference and GC as working electrode in 1M NaOH.
NB:
1. No leakage in RE as I have checked a couple of times and I have about 3 of these REs at my disposal, so I can interchange and check if there is any leakage (issues) with either of them. The aligator clips look good and have also interchanged with spare.
2. No mechanical vibration / interference as the lab is set up in the basement of the building and the experimental setup is on a standardized experimental bench. In addition, am not working on a hanging electrode.
3. From the picture, I have worked between -0.7eV and 0.6eV. However, I do work also in the range of 0eV and 1.4eV
4. The experimental solution has been prepared hours prior to the the measurement, and given enough time to acclimatize to the room temperature. As regard to the GC electrodes, I follow the standard rules. Polishing via the "8" pattern using 0.05um polishing alumina once in 5 days on the polish and DIW for rinsing.
Do you have any other suggestion?
Thank you
Some time there is a little bit of imbalance in the working electrode rotation gear so I suppose when you increase rpm the noise will increase, so it probably comes from that and you can fix it then
Yurii V Geletii
Yes, sensitivity is low.
I intentionally set it to a low value, so that i may be able to see the voltamogram as the measurements are taken. Moreover, i seldom get an overflow at very low sensitivity.
Thanks
Just try to set a different sensitivity and see what happens. Surely, always check the contacts.
Yurii V Geletii
am actually in the lab, i have tried a different sensitivity.
The cables look good, moreover, i have spare. I have alternated them.
I suppose there should be a way to get rid of the noise.
Have you achieved the noise decrease at different sensitivity setting?
1. Check the current stability of the socket you are using.
2. Vibrations from other nearby instruments, instrument is not close to door.
3. Try to perform the experiment in the Faraday cage if possible.
4. Go for more cycles.
Try to increase the sample interval and sensitivity to 0.005 it might help (I remember something regarding the ratio between scan rate and sample interval)
To Yas Bam
Plz, open a new discussion related to your question. Clearly formulate your question. I don't understand what you are asking about.
Hi,
I agree with previous answers. Apart from this, you have to check the connections carefully. I don't know the system (electrode / connections). For example, if working with carbon paste electrodes, the paste has to be thoroughly compacted, if clips for connections are slightly corroded they have to be polished... to ensure proper connection.
Olawale Oloye
have you resolved your problem? I guess you are obliged to keep us informed.
Yurii V Geletii Naama Gluz Rayees Ahmad Rather Sri Lakshmi M.Teresa Fernández-Abedul
Good day colleagues,
Apologies for not updating on the discussion board, It has been hectic in the lab. I have tried some of the suggestions but the problem still persist. However, we planning to get a Faraday cage and experiment with it. I do observe that N2 evolution could be responsible for the noise.
My conclusion is that so many factors could be responsible for the noise and some are manageable. I do observed that some published data have noise in them.
Thanks so much for all your contribution
All suggestions are good as expected....You can the change the electrolyte concerntration (nearly 6M) & use KOH instead of NaOH. I never faced problem like this with KOH. Just try for your solution. There may several problems like:
i. Proper contacts between the electrodes, its get rust with extensive use.
ii. Instrument may not get proper voltage from the source, configure it.
iii. Vary the sensitivity.
You should consider the following points:
1.Mains hum 50 Hz
* Voltages induced in the input circuit of amplifier by electromagnetic coupling from transformers or electrostatic coupling from other part of circuit or other instruments
* eliminate by electrical screening
2.Others induced by
* X-ray apparatus, high voltage power lines, sparks and discharges from motors, car ignition, faulty relays, bad contacts, thermostat (fridge, drying oven)
* hard to eliminate
3. Drift (low freq. Noise) slow erratic variations, random fluctuations in voltage supply, random T variations
* use good power source
* wait for instrument to warm up
To get rid of the noise, always identify source of noise e.g. avoid ground loops, use shielding, e.g. Faraday cage.
Some time there is a little bit of imbalance in the working electrode rotation gear so I suppose when you increase rpm the noise will increase, so it probably comes from that and you can fix it then
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