Chemical Behavior Of Titanium And Platinum 

Since platinum is highly resistant to corrosion, it's preferred on the anode's external surface. It can ensure that current flow is maintained throughout all electrolyte media, and not cause an insulate layer. It isn't corrosive, therefore it's not a source of corrosion products. This makes it very affordable.
Platinum is inert when the fused salts and acids while it dissolves in the aqua regia. There is no danger from hydrogen embrittlement. You can read more about hydrogen embrittlement in A Brief Introduction to Hydrogen Embrittlement. It is one rare metal that is able to withstand the seawater's chlorides. https://energy-ti.com/