Synthesis of Pt-Loaded Y₂WO₆:Eu³⁺ Microspheres and Their Hydrogen-Sensitive Turn-Off Luminescence

Pt nanoparticles were loaded on Y₂WO₆:Eu³⁺ phosphor microspheres to enhance hydrogen sensitivity at low temperatures through turn-off luminescence. Mesoporous Y₂WO₆:Eu³⁺ microspheres were synthesized first by a hydrothermal method. Pt loading on the surface of the Y₂WO₆:Eu³⁺ microspheres was then carried out by a method of the self-regulated reduction of surfactants using aqueous K₂PtCl₄ solutions. Structural and morphological properties of unloaded and Pt-loaded Y₂WO₆:Eu³⁺ microspheres were investigated by various techniques such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The relative photoluminescence intensity of the Pt-loaded Y₂WO₆:Eu³⁺ microspheres, due to ⁵D₀ → ⁷F (J = 0, 1, 2, 3, 4) electronic transitions of doped Eu³⁺ ions, was found to decrease as low as 22% after the microspheres were kept in the hydrogen gas atmosphere at a low temperature of 150 °C for 15 min. Meanwhile, mechanisms underlying this turn-off luminescence of the Pt/Y₂WO₆:Eu³⁺ microspheres in response to hydrogen gas are illustrated in detail.