Effect of Alkali Metal Cations on the TiO2 P25 Catalyst for Hydrogen Generation by the Photoreforming of Glycerol

Abstract

AbstractThe effect of three aqueous chloride salts, NaCl, KCl and LiCl, on the photoreforming of glycerol over TiO2, and Pt promoted TiO2 catalysts, has been investigated. At concentrations between 0.01 to 0.05 M an enhancement in activity over the TiO2 catalyst by a factor of ~10 can be ascribed to the presence of the cation, with the effect occurring at increasingly high concentrations of salt in the order Li<Na<K. At salt concentrations above 0.05 the activity is strongly inhibited on the oxide surface for all the different salts but only slightly degraded on a Pt promoted catalyst, hinting that the effect of the chloride is to hinder the reduction step on the oxide surface.