How is PEMFC not a violation of the Laws of thermodynamics

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.



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> 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?
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> 
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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.


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