Application of insitu measurement of photo-induced variations in electron work function for in-depth understanding of thephotocatalytic activity of TiO _2 nanotubes

摘要

The electron work function (EWF) is the minimum energy required to move an electron at the Fermi level from inside a conducting material to its surface with zero kinetic energy. This fundamental parameter is directly related to many chemical, physical, and mechanical properties of materials. In this work, variations in EWF of TiO _2 nanotube arrays under light illumination were monitored insitu using a Kelvin probe in order to study the photon-induced electron excitation in the TiO _2 nanotubular arrays upon illumination. It was shown that the EWF could be used to investigate the electronhole separation and recombination, helping us to better understand the photo-activity of the photocatalytic material. This study has demonstrated that EWF provides an effective parameter for understanding of semiconductors photo-activities with different views that may not be achieved using traditional techniques, such as diffuse reflection spectroscopy and photoelectrochemical measurement.