Synthesis and photocatalytic properties of β-NaY(Gd)F₄:Yb³⁺,Er³⁺@W₁₈O₄₉ nanocomposites

Photocatalytic hydrogen evolution on specific semiconductor material has been the most promising method to meet the future energy demands. To increase the efficiency of the photocatalysis, the β-NaY(Gd)F₄:Yb³⁺,Er³⁺@W₁₈O₄₉ nanocomposites were successfully synthesized by a two-step hydrothermal method. It can be observed that the as-prepared nanocomposites have a layered structure; the inner layer is hexagonal-phase β-NaY(Gd)F₄:Yb³⁺,Er³⁺ nanorods, and the outer layer is W₁₈O₄₉ nanowires (NWs). Compared to the W₁₈O₄₉ samples, the nanocomposites show 160% increase in hydrogen production efficiency in a BH₃NH₃ aqueous solution under 980 nm irradiation. The enhanced photocatalytic activity of the nanocomposites can be attributed to their particular hierarchical structure. The effect of localized surface plasmon resonance (LSPR) on the surface of the W₁₈O₄₉ NWs and the upconversion luminescence of nanorods in inner layer can be simultaneously triggered at 980 nm. Subsequently, the luminescence of the nanorods can be partially absorbed by the W₁₈O₄₉ NWs to re-excite the LSPR oscillation of the nanocomposite. The reexcited LSPR effect improves the photocatalytic efficiency of the nanocomposite.