In my electrolysis experiment, I used a 9 volt battery, 1:100 mL baking soda:distilled water, and stainless steel electrodes. I noticed that the anode degraded faster than the cathode. Out of curiosity, is there a phenomena to explain this?
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$\begingroup$ Can you explain what you mean by degraded? $\endgroup$– James GaidisJan 19, 2019 at 16:10
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$\begingroup$ Deposits and erosion on the anode that inhibit function: EG I use it once and then I have to replace it, due to the fact that it stops producing as much gas. $\endgroup$– FelixJan 19, 2019 at 16:49
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Gosh! You would think that electrolyzing NaHCO3 with stainless electrodes would be a clean reaction to produce H2 and O2.
Perhaps OH. is powerful enough to attach to some atoms at the surface and make it more insulating. So, significant degradation could occur at the positive electrode because of oxidation.
Perhaps lower voltage and currents would be more gentle with the electrodes. And perhaps a more resistant grade of stainless would show less degradation (316 is more resistant than 304, and knife blades are typically 400 series, harder but less corrosion-resistant).
At the cathode, hydrogen would be produced in a nascent (atomic) state, which can reduce the oxide coating on stainless steel, making it active. This activity would not result in corrosion while the electrolysis is going on - it is being cathodically protected. This electrode would be a good conductor even as its protective oxide coat is reduced, but the anode will have its oxide coat thickened till it becomes somewhat insulated - or degraded.
A similar effect can be seen with aluminum.
answered Jan 20, 2019 at 14:24