Naturally, we are not happy with these results -but one must face reality: One or more of the following must be true: the H-upd mechanism as written in Eq. 23c is incorrect, or its kinetics are indeed described by Eq. 51a-b. Curiously, there is a possible physical explanation for such a peculiar pH effect: As is suggested by Marcus-type theories of electron transfer, the transition state through its solvation shell should carry a fractional charge, proportional to the symmetry coefficient. Since the charged proton acceptor or donor must carry the same sign as such fractional charge, they would unfavorably interact with such transition state (increase its energy), increasing the activation barrier. Alternatively, it has been recently proposed that the water structure at the interface increases activation barrier of the Volmer step with increasing pH in the case of KOH . When Eqs. 51a-b are factored right (Eqs.