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I need an inert anode to perform some electrolysis. I've tried graphite, which works to some extent, however I want to upgrade to titanium, which is pretty reasonably priced, and will perform better than the graphite.

My question is whether there is a difference between "Titanium oxide electrodes" and plain titanium. Does a titanium dioxide electrode need to be specially treated to give it more inert characteristics, or does the oxide layer form naturally on the titanium?

I ask because I have seen this type of electrode classified as a Mixed Metal Oxide (MMO) electrode, but I have also seen some say that titanium is inert on its own. I would like to now whether plain titanium is a viable electrode so I don't end up buying some that ends up corroding quickly during electrolysis!!

Any information in this subject would be greatly appreciated.

Thanks in advance!!

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  • $\begingroup$ What gives you the idea that titanium is better than graphite? Did you check the literature? What reaction? $\endgroup$ – Karl Jun 5 '18 at 20:53
  • $\begingroup$ I realize that graphite could be preferable under some circumstances, however several factors point me to choose titanium or some other metal electrode. First, graphite releases carbon particles into the solution during high amperage applications. Second, it is more difficult to attach wires to graphite electrodes. Third, graphite is found in rods, but I wish to increase the surface area of the electrode to increase speed of reaction. Finally, graphite seems to generate significant amounts of heat (because of its higher resistance) at high amperage applications. $\endgroup$ – rubikssolver4 Jun 5 '18 at 21:06
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Used as an anode, a normal untreated piece of titanium metal will "anodize", forming a non-conductive titanium dioxide coating. In my experience, the current through a large untreated titanium sheet anode drops below the milliamp level in under a minute.

But there are a variety of electrically conductive but oxidation resistant micron-scale coatings that can be formed onto titanium, including platinum (a "platinized titanium anode"); conductive oxides of common metals like Pb or Sn (lead dioxide or tin oxide); or conductive oxides of rare metals like Ir, Ru, or Ta (a "mixed metal oxide anode"). There are some decent electron microscope microstructure photos in Umicore's promotional catalog.

The advantage to using a "valve metal" like titanium or aluminum as the substrate on a coated anode is if part of the fancy conductive coating flakes off, the bare titanium just anodizes and stops conducting, rather than getting eaten away and dissolving into the electrolyte.

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