Abstract
Hydrogen isotope exchange between H/sub 2/, gaseous H/sub 2/O, and the surface hydroxyls of TiO/sub 2/, and oxygen isotope exchange between O/sub 2/, CO/sub 2/, CO, H/sub 2/O vapor, and the hydroxyls over TiO/sub 3/ were studied at room temperature in the dark and under illumination. Hydrogen isotope exchange between H/sub 2/O and the hydroxyls occurred rapidly in the dark, but the exchange involving H/sub 2/ did not occur at all even under illumination. Oxygen isotope exchange among H/sub 2/O vapor, CO/sub 2/, and the hydroxyls easily took place in the dark, but the exchange involving O/sub 2/ required band-gap illumination. Dioxygen isotope equilibration was much faster than the other photoexchange reactions. Although the oxygen exchange between O/sub 2/ and illuminated TiO/sub 2/ has been considered to involve lattice-oxygen exchange, the present experiments revealed that the hydroxyls of TiO/sub 2/ mainly participate in the exchange reaction. The oxygen exchange between O/sub 2/ and H/sub 2/O vapor was strongly inhibited by H/sub 2/O vapor itself probably because oxygen adsorption was retarded by adsorbed water. Oxygen in CO was not exchanged with the other substrates under any conditions tested.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
