Facile water-based preparation of Rh-doped SrTiO3 nanoparticles for efficient photocatalytic H2 evolution under visible light irradiation

Abstract

Fine particles of Rh doped SrTiO₃ (SrTiO₃:Rh) were prepared via a newly developed facile water-based process; stable aqueous precursor solutions were prepared by simple mixing of stable aqueous titania sol with Sr and Rh salts in the presence of an acrylic emulsion, then dried and finally calcined in air at 900–1050 °C. The SrTiO₃:Rh particles prepared at 1000 °C were smaller than 50 nm in diameter and exhibited much higher efficiency for H₂ evolution from methanol aqueous solution under visible light (e.g. 13.2% of quantum yield at 420 nm) than those prepared by conventional solid state reaction (∼5%). On the other hand, the SrTiO₃:Rh particles prepared from the aqueous titania sol without the acrylic emulsion or from other aqueous titania precursors with the acrylic emulsion were found to have an increased particle size up to 100 nm, and exhibited lower photocatalytic activity, indicating that the combination of the aqueous titania sol and the acrylic emulsion effectively suppresses the particle growth, and consequently yields SrTiO₃:Rh particles having a small particle size and high crystallinity, both of which are necessary to achieve highly efficient photocatalysis.