Thermal desorption study of surface hydroxyls on ZnO

Abstract

The desorbability of surface hydroxyls on ZnO was investigated by three different techniques: thermal desorption, infrared absorption spectroscopy and adsorption of water on hydroxylated ZnO. It was found that the thermal desorption spectrum of the surface hydroxyls has two distinct peaks at 493 and 543 K. The surface hydroxyls on ZnO which were considered to behave as an inert surface for water physisorption and which as a result play an important role in the appearance of a discontinuity in the water adsorption isotherm were identified to be those giving a peak at 543 K in the thermal desorption spectra. Furthermore, they also give rise to a broad band with a peak at 3540 cm^–1 in the infrared absorption spectra.