Photoinduced Reactions of Surface-Bound Species on Titania Nanotubes and Platinized Titania Nanotubes: An in Situ FTIR Study

Abstract

Photoinduced conversion of surface-bound species on titania nanotubes that were first oxidized and then reduced (Ti–NT–O2–H2) and on platinized titania nanotubes subjected to oxidation and reduction (Pt–Ti–NT–O2–H2) has been investigated by means of in situ FTIR spectroscopy. Bidentate and monodentate carbonates as well as bicarbonates and carboxylates are formed subsequent to exposure of both Ti–NT–O2–H2 and Pt–Ti–NT–O2–H2 to CO2. Formic acid was only observed on Pt–Ti–NT–O2–H2. UV illumination of the nanotubes led to an increase in the number of surface-bound species as a result of the further reaction with gas-phase CO2 with a greater increase in surface species on Ti–NT–O2–H2 than on Pt–Ti–NT–O2–H2. The underlying basis of the photoinduced increase in adsorbed species is discussed for both types of nanotubes. Photoinduced reactions of surface species also take place and are remarkably different on the two types of nanotubes. UV illumination of Ti–NT–O2–H2 converts bidentate carbonates and bicarbonates...