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 (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.

Inter-diffusion of Cu2+ ions into CuS nanocrystals confines the microwave absorption properties

The inter-diffusion of Cu²⁺ cations into CuS nanocrystals generates CuS@Cu_2−xS core–shell and Cu₂S NCs in the presence of ascorbic acid (AA) at varying precursor Cu²⁺ : Cu⁺ molar ratios. The inter-diffusion process has a confining effect on the microwave absorption properties.

Tuning plasmonic properties of CuS thin films via valence band filling

Tuning plasmonic properties of CuS thin films via electrochemical reduction by decreasing hole concentration in the valence band.