Surface functionalization of ZnO photocatalysts with monolayer ZnS

Abstract

A fundamental investigation of the interface properties of coupled semiconductor photocatalysts in view of enhancing visible light activity is presented. We show by photoemission spectroscopy that modification of ZnO with submonolayer films of ZnS, two materials with band gaps larger than 3.4 eV, results in an effective surface band gap narrowing to 2.8 eV. This reduces the photoexcitation threshold energy and thus potentially enhances the solar energy conversion capabilities of such a heterostructure photocatalysts. Furthermore, the characterization of the space charge region and work function of ZnS modified ZnO indicate improved surface properties for enhancing photocatalytic activity. © 2008 American Chemical Society.