[aivar6]

Why platinum splits the hydrogen atoms into a proton (H+) and electron (e-) in fuel cell? What is the reaction behind that and how platinum maintains its structure?

[Borek]

Platinum doesn't split them. The reaction is that of hydrogen (H₂) oxidation to H⁺. It happens that platinum electrode is the best for the process.

[aivar6]

But why this oxidation happens and why platinum electrode is the best for that process? I know the reactions of electrolysis and fuel cells but there is never shown the role of platinum in that.

[billnotgatez]

Does this link help?

http://www.technology.matthey.com/article/57/4/259-271/

The Role of Platinum in Proton Exchange Membrane Fuel Cells
Evaluation of platinum's unique properties for use in both the anode and cathode of a proton exchange membrane fuel cell  By Oliver T. Holton  and Joseph W. Stevens

[Enthalpy]

I'm not quite convinced that one can tell whether adsorbed hydrogen is an atom or an ion. There are so many electrons nearby in the metal that telling if one electron pertains to the hydrogen or not must be quite subtle.

The important part is that hydrogen leaves this electrode as a positive charge, and this is possible because the electrolyte, thanks to its polar nature, dissolves the proton.