S. Ohkubo et al., THE ROLE OF METAL-HYDRIDES IN ELECTRODE-REACTIONS ON METAL-OXIDE SEMICONDUCTORS, Journal of the Electrochemical Society, 143(10), 1996, pp. 3273-3278
Metal hydrides formed on metal oxide semiconductors during reduction i
n a hydrogen flow have been found to play an important role in electro
de reactions, especially in the oxidation of water. By using a rotatin
g-ring disk electrode, the difference in electrode kinetics between Ti
O2 reduced in a N-2 and a H-2 flow was clarified. The TiO2 used was ma
de by the sol-gel method, which allowed a large tunnel current. This a
lso allows us to compare the difference between oxidation by a hole tr
ansfer under light illumination, photooxidation, and by an electron tr
ansfer under a tunneling in the dark, tunnel oxidation. It has been fo
und that the collection efficiencies, N-8, in tunnel oxidation are ind
ependent of the rotational speed and much larger than those in photoox
idation. Some catalytic enhancement of the ring current due to oxidati
on products produced at the TiO2 disk and carried away to the Pt ring
is discussed.