Four-electron pathway: Oxygen is directly reduced to water (O2 + 4H+ + 4e- → 2H2O). This pathway is preferred for high-efficiency energy conversion. Two-electron pathway: Oxygen is reduced to hydrogen peroxide (O2 + 2H+ + 2e- → H2O2). This pathway is less efficient and can be corrosive to the system.
The choice of catalyst can influence which pathway is favored, with platinum often promoting the four-electron pathway.
