According to Equation ( ), four H + must be produced for every O2 in simulations of both models to match the stoichiometry of the water oxidation process. This is indeed found as shown in Table . The hole photocurrent under oxidizing conditions is assumed to be only due to consumption of holes in the catalytic reaction, and is calculated from 4×dO2/dt, where dO2/dt is the steady-state generation rate of oxygen for each set of simulation conditions. Species concentrations as a function of time are shown in Figures and.