The mechanism and material aspects of a novel Ag2O/TiO2 photocatalyst active in infrared radiation for water splitting

Abstract

The Ag₂O/TiO₂ catalyst produces hydrogen with water and water/methanol mixture upon irradiation with IR light. In this report, the material aspects and photocatalytic mechanism of an IR-active Ag₂O/TiO₂ photocatalyst for water splitting reaction were investigated. The Ag₂O/TiO₂ catalyst contained 28% silver and 72% titanium by w/w and the XPS and XRD results revealed the presence of Ag₂O (Ag⁺), Ag⁰, TiO₂ (Ti⁴⁺) and Ti³⁺ states in the Ag₂O/TiO₂ catalyst. A solid proof of the IR photon-initiated catalytic activity of the Ag₂O/TiO₂ catalyst was observed from the clear and enhanced IR response in the incident photon current conversion efficiency measurements of the Ag₂O/TiO₂ catalyst. Comparing the band gap energies to the energy of the IR source, plasmon-assisted photocatalytic activity and/or sub-band gap phonon-assisted multi-photon excitation mechanisms are proposed for the observed infrared photocatalytic activity of the Ag₂O/TiO₂ photocatalyst and the functions of Ag₂O and TiO₂ in “dark photocatalysis” are discussed.