How to Make manganese dioxide electrodes
Various electrochemical reactions requires that anodes do not degrade when used. Carbon is cheap, but degrades easily and platinum is extremely expensive. In a previous video, you learned "How to make cobalt and manganese nitrates", and you saw that titanium could be used as a cathode, but not as an anode due to an effect called passivation.
Watch this science video tutorial from Nurd Rage on how to make manganese dioxide electrodes with Dr. Lithium.
These manganese dioxide electrodes that can be used for chlorate cells or HHO cells and a few other electrochemical processes requiring inert anodes in oxidizing solutions.
Making the electrode is fairly simple. First, a titanium strip is sanded to give a clean surface, and then etched with hydrochloric acid to activate it. Cobalt nitrate solution is applied in a thin layer and then heated to 300 Celsius to decompose (pyrolyze) the cobalt nitrate into cobalt oxide. The loosely adhering cobalt oxide is washed off and then new layers of cobalt oxide are applied—usually between 3 to 10 layers.
Then manganese nitrate is applied and the process repeated to make manganese dioxide. Another 10 to 50 layers may be applied.
Optionally, a further layer of manganese nitrate by electrolysis may be applied by using the electrode as an anode in a solution of 90 grams manganese sulfate, 500mL water and 12mL concentrated sulfuric acid. Copper or titanium is used as the cathode and a current density of about 10ma per square centimeter is used. A short run time of a few minutes or so puts a thin layer of manganese dioxide on the surface that seems to reduce permanganate production, but does not eliminate it.
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