where J ph is a photoelectrochemical assay of the flux of water oxidation with the unit of h + nm -2 s -1 , hs + is the surface holes concentration with the unit of h + nm -2 , α is the apparent order of the reaction with respect to the hole concentration and kWO is the corresponding effective water oxidation rate constant in the unit of nm 2α-2 s -1 . From this equation, log J ph = log kWO + α log hs +