Inspired by the anti‐freezing mechanisms found in nature, ionic compounds (ZnCl2/CaCl2) are integrated into cellulose hydrogel networks to enhance the freezing resistance. In this work, cotton cellulose is dissolved by a specially designed ZnCl2/CaCl2 system, which endows the cellulose hydrogels specific properties such as excellent freeze‐tolerance, good ion conductivity, and superior thermal reversibility. Interestingly, the rate of cellulose coagulation could be promoted by the addition of extra water or glycerol. This new type of cellulose‐based hydrogel may be suitable for the construction of flexible devices used at temperature as low as −70 °C.

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Ba 1.8−x Sr x SiO 4 :0.1Ce 3+ ,0.1Na + (x = 0−1.8) phosphors were prepared by a high-temperature solid-state reaction. The emission peaks of Ba 1.8−x Sr x SiO 4 :0.1Ce 3+ ,0.1Na + shift from 391 to 411 nm with increasing Sr 2+ content under excitation by a UV light at around 360 nm. Ba 0.4 Sr 1.4 SiO 4 :0.1Ce 3+ ,0.1Na + phosphor exhibits the best performance of luminescence, whose absolute quantum efficiency is 97.2%, and the emission intensity at 150 °C remains 90% of that at room temperature. The effect of replacing Ba 2+ by Sr 2+ on the red shift of the emission band and the increase of quantum efficiency (QE) and thermal stability (TS) was investigated in detail based on the Rietveld refinements, Raman spectra, thermoluminescence, and decay curves, etc. The performance of UV chip-based pc-LEDs indicates that Ba 0.4 Sr 1.4 SiO 4 :0.1Ce 3+ ,0.1Na + can be a promising blue phosphor for white-emitting pc-LEDs.

Photoluminescence quantum efficiency (QE) and thermal stability are important for phosphors used in phosphor-converted light-emitting diodes (pc-LEDs). LiSrCa(SiO):0.03Ce (-0.7 ≤ x ≤ 1.0) phosphors were designed from the initial model of LiSrCa(SiO):Ce, and their single-phased crystal structures were found to be located in the composition range of -0.4 ≤ x ≤ 0.7. Depending on the substitution of Sr for Ca ions, the absolute QE value of blue-emitting composition-optimized LiSrCa(SiO):0.03Ce reaches ∼94%, and the emission intensity at 200 °C remains 95% of that at room temperature. Rietveld refinements and Raman spectral analyses suggest the increase of crystal rigidity, increase of force constant in CeO, and decrease of vibrational frequency by increasing Sr content, which are responsible for the enhanced quantum efficiency and thermal stability. The present study points to a new strategy for future development of the pc-LEDs phosphors based on local structures correlation via composition screening.

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The concept of dual-excitation dual-emission (DE 2 ) phosphors for the enhancement of solar energy conversion is introduced in this work. Doping alkaline earth cations as an aggregated energy trap within the sulfur host in a controlled manner resulted in the DE 2 phosphors with tunable fluorescent emission properties. It had been found the Ca 0.6 Sr 0.4 S:0.005Cu + ,0.001Eu 2+ phosphor is the optimal DE 2 composition. We demonstrated by field testing results their potentials in enhancing sunlight harvesting to increase production of agricultural plants. Time-dependent density functional theory calculations provide insights about their excitation and emission mechanisms. These DE 2 phosphors can be applied to a variety of fields, as additives to increase production of agricultural crops, as nanosensor and biolabeling materials for ultrasensitive or green-sensitive detection of biological species such as antibodies, DNA and cells, and other places.

To effectively leverage and convert cheap, abundant, and environmentally friendly solar energy is still an unaccomplished endeavor. In this work, we prepare and characterize the long-lasting red-light-emitting, singlephase Ca 2 Zn 4 Ti 16 O 38 phosphor by the sol-gel method with nonstoichiometry or addition of H 3 BO 3 as flux. Excitation and emission mechanisms are proposed and supported by the computational results from density functional theory. Phase identification of powders was performed by X-ray powder diffraction analysis, confirming the existence of single-phase Ca 2 Zn 4 Ti 16 O 38 crystals in samples of every series. Unit cell parameters of the crystal were subsequently determined, together with its excitation spectra in the blue-green region with the maximum peak at 474 nm monitored by 644 nm light. The corresponding emission spectra showed a wide emission range with two narrow bands at 614 nm ( 1 D 2 f 3 H 4 ) and 644 nm ( 3 P 0 f 3 F 2 ) after the addition of H 3 BO 3 . If excited at 474 nm, the phosphor displays a superlong afterglow with the emission peak at 614 nm, enabling it to be a novel persistent red long phosphor for visible-light conversion. Luminescent properties of the phosphor were thoroughly examined. The mechanism of the dual persistence phosphorescence originated at 614 and 644 nm wavelengths induced by two separate kinds of doping defects was proposed. Density functional theory calculations under the periodic boundary condition provide insights about their excitation, emission, and long-lasting phosphorescence mechanisms.

Density functional theory has been widely used to investigate the structural and electronic properties of heme-containing proteins such as cytochrome P450. Nevertheless, recent studies have shown that approximate exchange-correlation energy density functionals can incorrectly predict the stability order of spin states in, for instance, iron-containing pyridine and imidazole systems. This raises questions about the validity of earlier theoretical studies. In this work, we systematically investigate a few typical inorganic and organic iron-containing complexes and try to understand the performance difference of various density functionals. Two oxidation states of iron, Fe(II) and Fe(III), with different spin states and both adiabatic and vertical structures are considered. A different description of the outmost molecular orbital is found to play the crucial role. Local density and generalized gradient based functionals bias the lower spin state and produce a more localized frontier orbital that is higher in energy than the hybrid functionals. Energy component analysis has been performed, together with comparison of numerous structural and electronic properties. Implications of the present work to the theoretical study of heme-containing biological molecules and other spin-related systems are discussed.