Effect of Na 2CO 3 addition on photocatalytic decomposition of liquid water over various semiconductor catalysis

Abstract

Photocatalytic decomposition of liquid water into H 2 and O 2 over various semiconductor catalysts, such as TiO 2, Ta 2O 5 and ZrO 2, suspended in pure water, was studied with a special interest on the effect of Na 2CO 3 addition. It was found, for the first time, that both RuO 2Ta 2O 5 and NiO x Ta 2O 5 photocatalysts were able to decompose liquid water into H 2 and O 2 in pure water as well as with the addition of Na 2CO 3. It was speculated that a negative flat-band potential and wide band gap of the photocatalysts are very important for the stoichiometric decomposition of liquid water. Furthermore, the addition of Na 2CO 3 is very effective for the photocatalytic decomposition of water for PtNa 2Ti 6O 13, PtK 2Ti 6O 13 and Pt−K 4Nb 6O 17 catalysts which did not show photocatalytic activity in pure water. The significant effect of Na 2CO 3 addition was observed commonly for both the TiO 2 catalyst system and the Pt-loaded catalyst system.