Monday, January 27, 2020

everyday chemistry - Which electrodes do not corrode at all?


I had used spare pieces of metal to perform electrolysis. They all had the disadvantage that they corrode when used as anode - and some of the oxides are toxic (copper, chromium).


I've found that carbon, which can be harvested from pencils and old batteries does not corrode contrary to my expectations (I'd expect it to produce $\ce{CO2}$). But soldering on carbon is completely impossible. Also, I need some bigger electrodes.


So are there any metals that do not corrode during electrolysis?


I'm using sodium carbonate as electrolyte.



Answer



This highly depends on what you are electrolyzing. When using solutions that are not very acidic, oxide-coated metals sometimes work, like lead-oxide electrodes, that can be harvested from old lead accumulators (attention, lead is toxic, wear lab coat and gloves when working with them. Lead accumulators contain ~20% sulfuric acid, so wear gloves as well and unassemble them in an acid-proof working space)



If you search the web for recipes of perchlorate preparation by electrolysis at home, you will find extensive discussions on the topic of anode materials and making oxidation-resistant electrodes.


Platinum is really hard to corrode, but even it corrodes in some cases.


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