And it is widely accepted that its photoluminescence (PL) emission is originated from the radiative transition between conduction band (CB), contributed by the π antibonding orbitals (π*) or δ* related to the sp 2 CN bond and valence band (VB) predominated by the lone pair (LP) in the edge N 2p orbitals. [3] Based on that the PL emission of g-C 3 N 4 in the region of 430-450 nm and 450-500 nm are ascribed to δ*→LP and π*→LP transition, respectively, the PL emission band can be controlled by adjusting π-conjugated polymeric network structure, the size of sp 2 CN clusters, layer packing, and defect degree. [4] However, pristine g-C 3 N 4 had low quantum yield (QY) and narrow range of PL emission (430-550 nm) due to its stable electronic band structure, [5] showing only slight changes in bandgaps upon different condensation precursors and reaction parameters (2.58-2.87 eV). [6] Over a decade, various functionalization strategies (including structural manipulation, [7] atomic/molecular doping, [8] and heterojunction construction [9] ) devoted to the electronic band structure adjustment, mainly aiming for the improvement of g-C 3 N 4 -related catalysis by enhancing their solar light (450-650 nm) is synthesized through the one-step molecular doping during the thermal condensation process of g-C 3 N 4 conjugated framework, which opens up its application beyond the conventional catalysis scopes. By adjusting the doped content of heteromolecules, the modified g-C 3 N 4 with the optical properties controlled according to the demand of practical applications can be facilely and largely obtained. It overcomes the limitation of the narrow adjusting range of conventional g-C 3 N 4 on optical properties and makes it become more promising for applications in solid-state displays. The corresponding multiple-color g-C 3 N 4 -based LED devices and the white-light LEDs with high quality can be obtained as supported by experiments and theoretical calculations. Moreover, the effect of doped molecule on the π-conjugated system of g-C 3 N 4 is systematically studied here, and the tunable luminescence mechanism is proposed.
Polymeric g-C 3 N 4 with controllable photoluminescence emission wavelength in the whole visible light range
Full-Color PhotoluminescenceThe ORCID identification number(s) for the author(s) of this article can be found under https://doi.
A multi-mode optical thermometer was developed using novel nanocomposite glass ceramics, containing bi-functional NaYF4:Yb3+/Nd3+ and NaAlSiO4:Cr3+ nanocrystals.
Fluorescent detection is a new spectroscopic measurement for ions sensing due to the advantages of real-time determination with high selectivity, accuracy, and low cost. However, chemosensors based on fluorescent detection are usually determined by absolute intensity from a monochromatic emission signal, which is easy to be fluctuated by the external environment, especially for Fe 3+ detection in complex fluids. Herein, we rationally design a dual-emission Eu 3+ : CDs@ZIF-8 to construct a ratiometric fluorescent sensor with self-calibrating ability for Fe 3+ determination. High efficient carbon dots (CDs) are embedded in europium ions (Eu 3+)-doped MOF by simple stirring preparation at room temperature. The label-free ratiometric fluorescent probe (I CDs@ZIF-8 /I Eu) exhibits simultaneous blue and red emission under the same excitation at 365 nm. Remarkably, Eu 3+ : CDs@ZIF-8 displays the superiority of high selectivity to Fe 3+ , which shows ratiometric fluorescence characteristics (I 0 /I) in a range of 0-6 μmol\L with a low limit of detection (LOD) of 0.897 μmol\L. Besides, the CDs-MOF nanocomposite holds good aqueous dispersibility and low cytotoxicity, which shows great potential applications in medical aid including biological detection and clinical diagnosis. K E Y W O R D S carbon dots, Fe 3+ detection, metal-organic framework, ratiometric fluorescent probe | 887 GUO et al.
Transparent oxyfluoride glass ceramics (GCs) containing LaOF:Er 3+ nanocrystals were synthesized. X-ray diffraction (XRD), Raman spectra and transmission electron microscope (TEM) confirmed the formation of LaOF nanocrystals in glass matrix. Energy dispersive spectrometer (EDS) results and Judd-Ofelt (J-O) intensity parameters demonstrated the incorporation of Er 3+ into LaOF nanocrystals. Enhanced 2.7 μm emission was achieved upon excitation with a 980 nm laser diode (LD). Upconversion, near-infrared emissions, and energy transfer mechanisms were studied to elucidate 2.7 μm emission behaviors. The enhanced 2.7 μm emission is most likely ascribed to the incorporation of Er 3+ ions into the low phonon energy LaOF nanocrystals. The excellent optical properties of this GC material indicate that it is a promising candidate for mid-infrared fiber lasers. , "Origin of near to middle infrared luminescence and energy transfer process of Er 3+ /Yb 3+ co-doped fluorotellurite glasses under different excitations," Sci. Rep. 5, 8233 (2015). 5. T.
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