Pressure dependence of electron- and hole-consuming reactions in photocatalytic water splitting on Pt/TiO2studied by time-resolved IR absorption spectroscopy

摘要

The decay kinetics of photogenerated electrons in the water splitting reaction on a Pt/TiO2photocatalyst was studied by time-resolved IR absorption spectroscopy. The decay of the photogeneratedelectrons within 2μs was decelerated when the catalyst was exposed to water vapor. The holes were consumedby the reaction with water instead of by the recombination with the electrons. On the other hand,the decay at 10–900μs was accelerated by the exposure. The electrons were consumed by the reaction withwater. The rate of the hole-consuming reaction was independent of the pressure of water vapor, whereasthat of the electron-consuming reaction increased with the pressure from 1 to 10 Torr. The different pressuredependences indicate different reactants involved in the oxidative and reductive reactants.