User:Gary thelake/sandbox PEM

Platinum demonstrates the highest activity toward HER and holds high corrosion resistance properties in the acidic PEM environment. Degradation phenomena on anodic and cathodic catalysts differ significantly. Anode catalysts have to withstand very aggressive operation conditions: high potentials (>1.5 V vs RHE) and low pH, presence of oxygen gas at elevated pressures, mechanical stresses due to oxygen bubble formation and potential cavitation in the porous structure of the catalyst layer, local hot spots due to high current densities or recombination of the produced oxygen and hydrogen crossing over the membrane. Cathodic catalysts are subject to less aggressive conditions with lower potentials (<0 V vs RHE), but must face formation of OH° radicals and H2O2 due to electrochemical reduction of oxygen crossing over the membrane from the cathode and mechanical stresses due to hydrogen evolution in the catalyst layer."Electrochemical Power Sources: Fundamentals, Systems, and Applications.pdf"