I was trying to understand how the proton-exchange membrane fuel cell works. Online I read that in such a cell hydrogen is oxidized at an anode catalyst, mostly platinum, and a detached electron ends up going through the circuit.
My doubt is where is the energy coming from?
That the catalyst can split hydrogen molecules for ever, isn't this a violation of the Laws of Thermodynamics? If the platinum is oxidizing the hydrogen, it must get depleted some time later?
ps: im in high school
If you want to understand the thermodynamics of a redox reaction, you have to look at both half-reactions. You are discussing the half-reaction that provides the electrons (and the protons):
$$\ce{H2 -> 2H+ + 2 e-}$$
There has to be a second half-reaction that consumes the electrons, e.g.
$$\ce{O2 + 4H+ + 4e- -> 2 H2O}$$
In combination, this is a redox reaction where the equilibrium lies on the side of the products.
$$\ce{O2 + 2H2 -> 2 H2O}$$
Those types of reactions can be used to generate electricity.
Like if this catalyst can split the hydrogen molecules for ever , then isn't this a violation of the Laws of Thermodynamics? If the Platinum is oxidizing the hydrogen , it must get depleted some time later?
The platinum is a catalyst. It affects the speed of the reaction (the kinetics), but not on which side the equilibrium lies (thermodynamics). The other half-reaction is oxidizing the hydrogen, and platinum is just a catalyst.
