PHOTOCHEMISTRY AT HIGH-TEMPERATURES - POTENTIAL OF ZNO AS A HIGH-TEMPERATURE PHOTOCATALYST

Direct conversion of solar radiation into useful, storable and transpo rtable chemical products is the primary goal of solar chemistry. In th is paper we discuss some fundamental aspects of photochemistry at elev ated temperatures. We show that luminescence can serve as an indicator of the potential use of a system as a photoconverter. As an example w e present experimental data on the chemical potential and on the lifet ime of the excited states of ZnO. The low luminescence quantum yield t ogether with a lifetime of about 200 ps indicate that an efficient pho tochemical conversion on ZnO is highly improbable. We believe this to be a general feature of chemical systems based on a semiconductor phot ocatalyst, in particular of photoreactions at a solid/gas interface.