Current-doubling Reaction of Oxalate at a Zinc Oxide Photoanode

Abstract

The cu rra t-d o ubling behavior of oxalate was studied at an n-type zinc oxide polycrystalline semiconductor photoanode. The increase in photocurrent due to oxalate was 92∼96% in a weak acidic electrolyte solution (pH 4.4∼5.6). However, it was found that in the weak acidic solution during the current-doubling reaction the zinc oxide photoanode dissolved.
On the other hand in the alkaline solution (pH 12.6), the photoanodic dis solution reaction of zinc oxide was completely suppressed and no current-doubling was observed. From the experimental results a reaction mechanism is proposed.