Preparation of Y2SiO5:Pr3+,Li and Na2NbxTa2−xO6/(Au/RGO) composites and investigation into visible-light driven photocatalytic hydrogen production

Abstract

A visible-light-driven photocatalytic hydrogen production system (Y₂SiO₅:Pr³⁺,Li/Na₂Nb_xTa_2−xO₆/(Au/RGO)), which is composed of an up-conversion luminescence agent (Y₂SiO₅:Pr³⁺,Li), Nb(V)-substituted Na₂Ta₂O₆ (Na₂Nb_xTa_2−xO₆) and a combined co-catalyst (Au/RGO), is designed and the photocatalytic hydrogen production activity is studied using methanol as the sacrificial agent in aqueous solution. In the employed composite nanoparticles, the Y₂SiO₅:Pr³⁺,Li/Na₂Nb_0.5Ta_1.5O₆/(Au/RGO) system with 0.4 : 1.0 mass ratio of Y₂SiO₅:Pr³⁺,Li and Na₂Nb_0.5Ta_1.5O₆ affords the highest amount of hydrogen production under visible-light irradiation, which is 2.3 times higher than that of Na₂Nb_0.5Ta_1.5O₆/(Au/RGO). The high photocatalytic hydrogen production activity is attributed to the spectrographic matching between Y₂SiO₅:Pr³⁺,Li and Na₂Nb_0.5Ta_1.5O₆/(Au/RGO). That is, the ultraviolet-light (230–320 nm) from the up-conversion emission of Y₂SiO₅:Pr³⁺,Li can effectively activate Na₂Nb_0.5Ta_1.5O₆/(Au/RGO). The presence of Nb can lead to the adjustment of the band-gap of Na₂Ta₂O₆ to broaden the light response range. In addition, Au/RGO can quickly separate the photo-generated electrons and holes and further enhance the photocatalytic hydrogen production activity.