Contrary to previous suggestions regarding the magnitude of the electrostatic surface potential, fast kinetics are not entirely based upon the strength of the intrinsic dipole moment of the adsorbate. As we observed for CO 2 reduction on CeO 2 , the intrinsic dipole moment of the carbonate is relatively large (⃗ µ ⊥ = 1.09e), yet the shift in electrostatic surface potential is zero. This results from the neutrality of the adsorbate (CO x 3 O ) and the absence of charge separation, meaning that the carbonate will only experience a change in the chemical potential under an applied overpotential (Table ). 9