Using Titanium (Ti) felt as an anode current collector—typically for Proton Exchange Membrane (PEM) water electrolyzers or regenerative fuel cells—is a standard industry practice. Because the anode operates at high oxidative potentials (often >1.6 V vs. RHE) in an acidic environment, Titanium is one of the few metals that doesn't dissolve. However, Ti naturally forms a resistive TiO2 layer. Electroplating it with Platinum (Pt) serves two purposes: it prevents the oxide layer from thickening and provides a highly active catalytic surface for the Oxygen Evolution Reaction (OER) or other targeted electrochemical processes.

Plating a 3D porous structure like Ti felt is significantly more complex than plating a flat sheet. (1) Surface Pre-treatment (The "Make or Break" Step): Titanium is "bio-inert" and chemically stubborn. To get Pt to stick, acetone or alkaline can be used to wash to remove manufacturing oils. (2) Etching: Boiling in 10% Oxalic Acid or a HF/HNO3 mixture to strip the TiO2 layer and roughen the fibers. (3) Activation: Immediate immersion in the plating bath or a dilute HCl "strike" to prevent the oxide from reforming during transfer.

 In PEM electrolyzers, the Pt-coated Ti felt is used at the anode because Carbon GDLs would oxidize and turn into CO2 at the high operating potentials. While Pt is a good OER catalyst, it is often used here primarily as a protective, conductive coating. Sometimes, a secondary layer of Iridium (Ir) or Ruthenium (Ru) is added over the Pt for even higher OER activity.