In the present work, we reported the luminescence of a green-emitting carbon dots (CDs) synthesized via solid state reaction method using diammonium hydrogen citrate and urea as a starting materials. The obtained green-emitting CDs shows strong absorption in the 350–450 nm region and gives intense green emission (λmax = 537 nm) with quantum yield as high as 46.4% under 420 nm excitation. The obtained green-emitting CDs also demonstrates high photo-stability, which is evidenced by the fact that its emission intensity almost has no change under irradiation by a 365 nm UV lamp for 2 hours. Moreover, the obtained green-emitting CDs shows high sensitivity and selectivity for the detection of Fe3+, and their emission intensity response towards Fe3+ ions is highly linear (R2 = 0.995) over the concentration range from 25 to 300 µM, which could provide an effective platform for detection of Fe3+. Mostly important, we further demonstrate that such photoluminescent green-emitting CDs exhibits low toxicity and are biocompatible for use with in cellular imaging. Combining with low cytotoxicity, good water solubility and excellent luminescence properties, green-emitting CDs could be used as a biocompatible fluorescent ink in future applications.

All-inorganic CsPbBr 3 perovskite quantum dots (PQDs) exhibit excellent photoelectric properties and application prospects in the field of lightemitting diodes (LEDs) and display devices. However, these possess poor long-term stability to UV irradiation, water, heat, and oxygen. Using polymethyl methacrylate (PMMA) as the matrix along with CH 3 (CH 2 ) 16 COOCs, [CH 3 (CH 2 ) 16 COO] 2 Pb, and KBr as the perovskite sources, CsPbBr 3 PQDs/ PMMA composites are for the first time prepared via an in situ polymeric melt encapsulation method. Special attention is paid to the effects of synthesis conditions on the photoluminescent quantum yield (PLQY) of the composites. The optimized CsPbBr 3 PQDs/PMMA composite reveals excellent performance with ≈82.7% PLQY and ≈18.6 nm full width at a half-maximum (FWHM). In particular, after 90 h of UV irradiation or 35 days of heating at 60 °C, the luminous intensity remains almost unchanged. In addition, after soaking in water for 15 days, it retains up to ≈53% of the initial luminous intensity, meaning that the composite possesses long-term stability to UV irradiation, heat, and water. The as-prepared white LED (WLED) based on the composite evidences the wide color gamut (126.5% National Television System Committee (NTSC)) and a luminous efficiency of 32 lm W −1 . This work offers a novel, easily industrialized one-step, and solvent free route for lowtemperature synthesis of all-inorganic PQDs with broad application prospects.

A series of BaLi 2 Al 2 Si 2 N 6 (BLASN): xEu 2+ phosphors are successfully synthesized and their crystal structure and luminescence properties under varying hydrostatic pressures are reported herein. Structure variation is analyzed using in situ high-pressure X-ray diffraction and Rietveld refinements. Based on decay curves and Gaussian fitting of emission spectra, the presence of two photoluminescence centers is demonstrated. BaLi 2 Al 2 Si 2 N 6 : 0.01Eu 2+ exhibits an evident peak position shift from 532 to 567 nm with an increase in pressure to ≈20 GPa. The possible factors and mechanisms for the variations are studied in detail. At a pressure of 16 GPa, BLASN: Eu 2+ realizes a narrow yellow emission with a full width at half maximum of ≈70 nm. The addition of BLASN: Eu 2+ (16 GPa) to the commercial white light-emitting diodes combination consisting of an InGaN chip, β-SiAlON: Eu 2+ , and red K 2 SiF 6 :Mn 4+ , can increase the color gamut by ≈15%, demonstrating the promising potential of pressure-driven BLASN: Eu 2+ for wide-color gamut spectroscopy applications. Moreover, the emission shifts arising from pressure variation and the distinct color changes enable its potential utility as an optical pressure sensor; the material exhibits high pressure sensitivity (dλ/dP ≈ 1.58 nm GPa −1 ) with the advantage of visualization.

The Cu-based nanocatalysts have shown a high selectivity toward selective hydrogenation reaction, but the underlying catalytic mechanism is still murky. Herein, we report a new gram-scale strategy for realizing the single atom Cu site incorporated into the melem ring of graphitic carbon nitride (Cu 1 /CN) for understanding the catalytic mechanism of a hydrogenation reaction. The as-synthesized Cu 1 /CN exhibits unprecedented selectivity (100%), high activity (TOF = 2.9 × 10 3 h −1 ), and outstanding stability for selective hydrogenation of 4-nitrostyrene. We reveal that the presence of hydroxymethyl from trimethylolmelamine is beneficial to atomically disperse Cu atoms in the CN. X-ray absorption fine structure tests reveal that the Cu atom of Cu 1 /CN is dominated by the quaternary coordination way (Cu−N 4 ) in the melem ring of CN. Density functional theory calculations confirm that the high reactivity and selectivity originate from the anchored Cu sites creating the optimal chemical environment for the highly efficient hydrogenation reaction.

As the core component of this emerging field, the broadband NIR light source needs to be small and exquisite to meet the application requirements. Compared with traditional broadband NIR light sources such as the bulky tungsten-halogen lamps, broadband NIR phosphor-converted light-emitting diodes (NIR pc-LEDs) is proposed as an ideal compact light source due to their advantages of environmental protection, energy-saving, long lifetime, and small size. [2] The strategy of NIR pc-LEDs is mainly realized by coating broadband NIR phosphor on a blue LED chip. Among them, one of the important research topics is the exploration of broadband NIR phosphors that can be excited by blue light.Cr 3+ ion with d 3 electron configuration is the commonly used activator for NIR emitting phosphors. When it's located in a weak octahedral crystal field in a host, broadband NIR emission can be obtained due to the 4 T 2 → 4 A 2 transition. [3] The Cr 3+ -doped garnet phosphors are a typical broadband NIR luminescent material, showing high quantum efficiency and robust thermal stability. For example, Ca

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A novel K3ScSi2O7:Eu2+ based phosphor with broad-band NIR emission and robust thermal stability has been obtained.

A dipotassium hafnium trisilicate K2HfSi3O9 with wadeite structure was synthesized by solid-state reaction for the first time. Its detailed crystal structure and electronic structure were determined using XRD Rietveld refinement and density functional theory (DFT), respectively. An expected asymmetric emission band was observed in K2HfSi3O9:Eu2+ due to Eu2+ ions occupying the two symmetrically inequivalent K+ (K1 and K2) ion sites in the host lattice. The K2HfSi3O9:Eu2+ has obvious heat-sensitive luminescent features (25 °C, blue emission; 250 °C, green emission), which can be rationalized by the energy transfer from Eu1 to Eu2 under thermal stimulation. Moreover, we developed promising phosphor K2HfSi3O9:Eu2+,Sc3+ by employing the crystal-site engineering method, and tuned the emission color from blue to green with the variation of Sc3+ ions. The target phosphor K2HfSi3O9:2%Eu2+, 6%Sc3+ shows strong absorption in the spectral range of ∼250–490 nm and a narrow green-emitting band (fwhm ∼59 nm) peaking at ∼507 nm with zero emission loss at ambient temperature up to 200 °C. Such robust thermal performance was explained by possible transfer energy from the defect levels to the 5d band of Eu2+, and certified by the thermoluminescence spectrum and the decay curves in the temperature range of 25 to 250 °C. Combing this excellent green phosphor with n-UV (395 nm) or blue chips (450 nm), pc-WLEDs with high luminance, adequate color rendering index, and correlated color temperature were obtained.