On the Mechanism Responsible for the Catalytic Activity of Platinum for Oxygen Reduction Reaction (ORR) and predicting a cost effective replacement for Pt toward ORR
Pt is required as a catalyst for both oxygen reduction reaction (ORR) and hydrogen evolution reaction(HOR) . This means that any type of fuel cell or a configuration to split water into hydrogen and oxygen require platinum as a catalyst. Currently, much of the cost of fuel cells arises from the need for precious metal catalysts – primarily Pt – to drive the necessary electrochemical reactions. For example, the cost of the Pt alone in a PEFC for a small 100 kW car is higher than the cost of an entire 100 kW gasoline engine. And there is another problem. During the course of the lifetime of a fuel cell, the Pt cathode suffers from oxidation, migration, loss of active surface area, and corrosion of the carbon support. Impurities, as well as methanol diffusing from the anode side of DMFCs, can also ‘poison’ the catalyst, reducing its activity and efficiency. So not only do fuel cells rely on a high-price commodity for their operation, they also require a high density of that expensive material. Understanding the mechanism responsible for such material is necessary to reduce the cost of fuel cells and water splitting configuration. It is well known that the crystal structure of platinum is an face centered cubic (FCC). In this case the lattice constants which influence the bandgap energy are equal a. In fact it may be that the bandgap energy is inversely proportional to the inverse of the a**(3) [1] Based on the idea that the lattice constant influence the bandgap and the fact that the bandgap energy is the energy required to move the bonded valence electrons to free conduction band which is the energy required to do the rate limiting step for the ORR or HER, a mechanism for the effect of platinum will be derived. Reference [1] R. Da1ven, Phys. Rev. B, 8,12 1973 [2]D. Bensaid , International Journal of Metals, 2014 (2014), Article ID 286393, 7 pages