between the adsorbed species and the first layer of the surface, ⃗ E = V /r. However, modulating the adsorbate-electrode distance will result in energetically unfavourable distortion of the bonding. Therefore the shift in electrostatic surface potential is a result of a change in coverage of polar adsorbates, such that χ = (⃗ µ ⊥ ρ 0 θ)/ε 0 where ⃗ µ ⊥ , ε 0 , ρ 0 and θ represents the dipole moment normal to the surface, vacuum permittivity, density of available adsorption sites and adsorbate coverage, respectively. A positively charged adsorbate (Fig. ) imposes a negative electric field vector which points into the electrode surface ( ⃗ E = -∇ϕ). A neutral adsorbate (Fig. ) has no electrostatic attraction to the electrode and is therefore weakly bound to the oxide surface by dipolar interactions. Finally, a negatively charged adsorbate (Fig. ) imposes a positive electric field which points away from the electrode surface.