A series of K1–2x–2y Ba y Al11O17(KBAO):xEu2+ phosphors are designed to develop a blue phosphor with excellent thermal properties. All of the samples present similar β-Al2O3 structures with P63/mmc space group; the K+ vacancy can exist stably until the Ba2+ concentration exceeds around y = 0.3. KBAO:Eu2+ exhibits strong absorption for near-ultraviolet light and relatively standard blue emission. The mechanisms for excitation and emission spectrum variations have also been studied in detail. Based on the adjustment of K+ vacancy numbers in the defect structure, K0.6Ba0.1Eu0.1Al11O17 exhibits a remarkable quantum yield of around 91.2% and a terrific high-temperature characteristic. The zero-thermal quenching performance mainly results from stabilization of the flowing electron number between Eu2+ 5d levels and K+ defect ε­(0/–1) and ε­(+1/0) levels in the processes of thermal ionization and recombination. A bright fabricated white-light-emitting diode (WLED) gives a color rendering index (CRI) of R a = 87 and a correlated color temperature (CCT) of 4510 K, demonstrating that KBAO:Eu2+ has application potential to provide a blue light component in WLED. In addition, our research is a significant attempt to achieving stable zero-thermal quenching by subjective structure design, which provides a reference value for investigating the excellent new phosphors.

The assembly between carbon materials and transition metals has been proved to be a feasible strategy to synthesize electrocatalysts with good activity and stability, especially those with carbon-encapsulated core–shell structures that were prepared through multiple processes. Via direct pyrolysis of kelp, we demonstrate in our work the successful synthesis a composite consisting of electrochemically active and graphene-encapsulated cobalt nanoparticles embedded in N, P, S codoped carbon three-dimensional matrix. This biomass-derived electrocatalyst is low-cost and more facile in preparation, and its typical structural features like hierarchical pore structure, high specific area and heteroatom doping enable it to serve as not only a promising cathode material for oxygen reduction reaction (ORR) in fuel cells but also a counter electrode material for triiodide reduction reaction (TIRR) in dye-sensitized solar cells. More importantly, the unique structure of multilayer-graphene-encapsulated cobalt nanoparticles is beneficial to increase contact area, inhibiting the aggregation and dissolution of metal nanoparticles, thus improving the electrocatalytic performance and stability for ORR and TIRR.

Nowadays liquid crystal displays (LCD) backlighting has become an independent subject of the display field, and gradually formed a research and development hotspot. The narrow-band emitting phosphors which play an...

The multiplexing capacity of conventional fluorescence materials are significantly limited by spectral overlap and background interference, mainly due to their short-lived fluorescence lifetimes. Here, we adopt a novel Gd3+ doping strategy in NaYF4 host materials, realized tuning of upconversion photoluminescence (UCPL) lifetimes at selective emissions. Time-correlated single-photon counting (TCSPC), was applied to measure the photoluminescence lifetimes accurately. We demonstrated the large dynamic range of lifetimes of upconversion nanoparticles with good upconversion quantum yields, mainly owing to the dominance of high efficient energy transfer upconversion mechanism. The exceptional tunable properties of upconversion materials allow great potential for them to be utilized in biotechnology and life sciences.