Controlling the Schottky Barrier at the Pt/TiO<sub>2</sub> Interface by Intercalation of a Self-Assembled Monolayer with Oriented Dipole Moments
Taishi Ano, Fuminao Kishimoto, Shuntaro Tsubaki, Yi‐Hsien Lu, J. Nathan Hohman, Masato M. Maitani, Miquel Salmerón, Yuji Wada
Abstract
Interfacial Schottky barriers can impact the catalytic function of Pt on TiO2. Since the electronic structure is characteristic of each material, it may be advantageous to tailor the interfacial Schottky barrier by the addition of adsorbed layers. Here, we show that the Schottky barrier in Pt/TiO2 can be mitigated by the insertion of self-assembled monolayers (SAM) of carboranethiols that possess an oriented dipole moment. A Pt substrate with the SAM on which TiO2 nanoparticles are deposited is used to that effect. Kelvin Probe Force Microscopy shows that m-9-carboranethiolate SAM with perpendicular dipole moments decreases the potential difference between TiO2 and Pt by ∼0.3 eV due to the interfacial electric field of the SAM. Our findings open new opportunities for tailoring interfacial electronic structures not only in the metal–semiconductor junction, but also the semiconductor heterojunctions.