Introduction: Electroplating Metal Oxides Onto Electrodes
This is something I stumbled upon while experimenting with battery chemistries. Figured I'd share considering there is almost no information on this subject that I could find just like my last instructable-
A method for plating oxides onto metals
This method has been confirmed to work with iron oxide and copper oxide, a slight modification is needed for nickel hydroxide and zinc oxide.
Disclaimer: I hold no liability for anything resulting from your use of the information or lack of information contained within this instructable. You have been warned!
1. Magnesium sulfate heptahydrate (C.A.S # :10034-99-8 )
2. Water (yes it is considered a chemical) (C.A.S#: 7732-18-5 IUPAC Name: Oxidane)
H2O + MgSO4 + Metal + -e --> H2 + MgSO4 +Metal Oxide
Step 1: Gather Your Materials
1. Distilled Water
2. Magnesium Sulfate Heptahydrate (Epsom Salt)
3. Metal who's oxide you would like to plate onto the electrode
4. Power Source (‘D’ size battery or anything between 0.4-1.7 volts that can handle a higher amperage)
5. Volt Meter (always handy but not necessary)
6. Random Bits of Wire
7. Small Clamps
Step 2: Mix the Solution and Hook Everything Up
Attach the metal electrode (in this case the iron nail) to the positive (+) and the electrode to be plated to the negative (-) and dip them into the solution.
Step 3: Entertain Yourself for a While
The aluminum foil electrode didn't work out so I tried a brass rod. It took around 6 hrs. to get a decent coating on the brass electrode at between 1.54 -> 1.48 volts as the battery discharged.
Keep the voltage low or the oxide layer will just peel off.
This particular method I have tested to work with both iron and copper oxides. I don't have the time or resources to test every metal so it will be subject to personal experimentation.
Step 4: The More "Universal" Approach.
This second method can be used for some of the more "stubborn" metals like nickel as well as metals like zinc. It can also be used in place of the first method when the base metal is not available as the metal itself.
Step 5: Prepare an Inert Electrode
In this step I used pure nickel wire as the positive (+) electrode due to it's relative inertness in this particular solution. Nickel, however, may eventually dissolve after a few days of sitting in the solution. Make sure the electrode covers the bottom of the container as shown in the picture, and make sure the electrode touches the bottom of the container as well. It is important that the electrode makes good contact with the oxide.
Step 6: Prepare the Solution
Prepare the solution as in the previous process taking care to make sure the MgSO4 is completely dissolved before moving on to the next step.
Step 7: Adding the Oxide
Pour in enough of the powdered oxide to cover the electrode on the bottom and wait for everything to settle. In this case I used ACS reagent grade black nickel oxide.
Step 8: Set Up the Electrodes and Electrolyze
Attach the inert electrode with the oxide to the positive (+) and the electrode that its going to be plated onto to the negative (-) and apply a high voltage (3-5v, "high" being a relative term as most electrolysis reactions in aqueous solutions are carried out below 2v).
The only differences between this process and the previous process is the use of the inert metal/metal oxide electrode and the working voltage needed to ionize the metal into solution. I have been having some problems with adhesion of the coating and through some experimentation I found that a thin coating seems to work the best. In previous experiments, however, I did find that the nickel oxide adhered to galvanized steel alright but quickly flaked off upon drying. This method isn't the best process but is the least "chemically intensive" (referring to the fact that the only chemicals consumed in this process are the electrode or oxide, and water (oxygen source and ion carrier) making it essentially a semi-catalytic process (with the input of electricity of course)) and can be carried out at room temperature without the need for sintering or baking making it less energy intensive as well.
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This is interesting. I have a carbon steel knife that I want to deposit an oxide coating on for corrosion resistance. I would really like to know more about the durability of the coatings you can form with these methods. If a knife is used for hacking and splitting wood, it could put quite a bit of stress on the coating. I would really love to be able to do something at home rather than take it to a plating shop and probably double the cost of the knife (or more). When we were in school, my brother and I played around a bit with electroplating metals, but we could never form a coating that didn't rub off fairly easily (even with careful surface prep). Love to know more. Thanks!
Well, this method I mainly use for making battery plates so I've really only made thick coatings. The durability of the coating isn't the greatest but I haven't tested any thin coatings yet. You could try plating a nail and pounding it into a block of wood a few times to test the durability. In this case a more commercial method might be better. Here are a couple of articles on the process of oxide coating. It seems like it would fairly easy to make something to utilize one of these processes. Sorry I couldn't be more help.
How could I use metal oxide anodes in electrolysis and electroplating in my home lab?
That all depends on the oxide used. Some oxides are used in battery plates such as nickel oxide and iron oxide in a nickel iron battery, cadmium and nickel oxides are used in ni-cd batteries, mixed metal oxide electrodes (Ru, Ir, Pt oxides) are mainly used to produce chlorine gas which has many chemical applications such as the production of hydrochloric acid. My post https://www.patreon.com/posts/chlorine-gas-to-15665121 outlines a couple of the uses of chlorine. Manganese dioxide is used as an oxidizer in alkaline batteries, red copper oxide is a semiconductor and an inefficient solar panel can be made from it, as well as diodes, and a catalyst for converting CO2 and water to methanol using sunlight if you can get copper oxide nanorods, and automotive oxygen sensors use zirconium dioxide as a high temperature electrolyte to conduct oxygen ions to name a few.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5049451/ talks about using a Ni-Fe oxide as an efficient catalyst for the evolution of oxygen through electrolysis. This type of electrode could probably be made using this process.