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Direct Measurement Of Diffuse Double-Layer Forces At The Semiconductor/Electrolyte Interface Using An Atomic Force Microscope, Kai Hu, Fu-Ren F. Fan, Allen J. Bard, Andrew C. Hillier

Andrew C. Hillier

The forces between a silica probe and an n-type TiO2 single-crystal electrode were measured using an atomic force microscope in an aqueous electrolyte solution. These interactions were a strong function of the solution pH, the presence of specifically adsorbed anions, and the TiO2 electrode potential. For a series of pH values, a strong electrostatic repulsion was seen at high pH and decreased as the pH was reduced. At pH values below 5.5, the interaction became attractive. A series of force measurements between SiO2 and n-type TiO2 showed a repulsive interaction when TiO2 was held at negative electrode potentials, which transformed …