Metal–Organic Framework‐Assisted Rational Design of Multicolor Solid‐State Fluorescent Carbon Nanodots and Its Application for LEDs

Abstract

Carbon nanodots (CDs) are a new type of carbon‐based fluorescent nanomaterials, but they are limited in many applications due to the inherent fluorescence weakening and quenching problems suffered in solid state. Herein, ZIF‐8, a class of metal–organic framework (MOF) is employed as a matrix to immobilize fluorescent CDs, resulting in the strong luminescence of CDs achieved in solid state. The as‐synthesized CDs@ZIF‐8 fluorescent powders possess blue, green, and red emissions with the main emission at ≈495, 528, and 600 nm, and the corresponding photoluminescence quantum yields (PLQYs) are as high as 25.89%, 52.24%, and 15.42%, respectively. It is found that the encapsulation of ZIF‐8 with CDs will increase the excitation dependence of the product fluorescence, which may be attributed to the carrier effect of ZIF‐8 as a carrier of CDs and some surface defects or surface functional groups change of the CDs introduced by ZIF‐8. In addition, the encapsulation of CDs with ZIF‐8 may result in the charge transfer. Importantly, the prepared CDs@ZIF‐8 phosphors present a promising application in the fabrication of monochromatic light‐emitting diodes (LEDs). The synthesis design is expected to provide technical support for future solid‐state fluorescent CDs preparation and applications.

Fluorescence ‘Turn-on’ Probe for Chromium Reduction, Adsorption and Detection Based on Cellulosic Nitrogen-Doped Carbon Quantum Dots Hydrogels

“…A OH A CH (10) where A 1425 and A 900 , A OH and A CH refer to the FTIR absorbance at 1425 cm −1 , 900 cm −1 , OH, and CH bands [8,18].…”

“…N-CQDs are spherical nanodots that combine diamond-like sp3 carbon and flat sheets of sp2 carbon. They can be prepared using an eco-friendly microwave method on agricultural waste [2,[8][9][10][11][12]. N-CQDs have attracted significant attention in chemosensing and adsorption applications due to their unique properties, including their minute size, optical properties, excellent hydrophilicity, tailorable surface chemistry, costeffective production, and straightforward fabrication.…”

Developing Luminescent Ratiometric Thermometers Based on Dual-Emission of NaMgF3:Eu3+/Carbon Dot Nanocomposites

“…Enlightened by the proposed strategy, an innovative dual-activated luminescent thermometer was created by exploiting the emissions of Ln ions and carbon dots (CDs) in nanocomposites. CDs are a class of green and environmentally friendly fluorescent materials with superior properties, including low toxicity, excellent biocompatibility, facial synthesis and unique physical characteristics. , Typical CDs, consisting of a graphite-like or amorphous core with various kinds of surface functional groups, are quasi-spherical carbon nanomaterials with a size of less than 10 nm. , CDs yield such a broadband emission in the blue, green, and yellow spectral regions with a high quantum efficiency, but the emissions are highly susceptible to temperature changes. − This suggests that CDs are particularly well suited as optical probes for improving temperature sensitivity. On the other hand, integrating CDs into nanocomposites facilitates the development of solid-state fluorescence of CDs, which holds significance in the fields of optoelectronics, biology, and sensor technology. − Especially, nanothermometry using luminescent nanoparticles has become an active field of research due to their small size, which allows mapping temperature profiles with excellent spatial and temporal resolution for remote temperature sensing .…”

Waste Polyethylene-Derived Carbon Dots: Administration of Metal-Free Oxidizing Agents for Tunable Properties and Photocatalytic Hyperactivity

“…In the top-down approach, larger graphitic structures are broken down into ultrasmaller dot structures. Such CDs are emerging as comparable to conventional semiconductor dots. ,− Since these are soluble in various solvents and contain many surface functional moieties, they can be easily functionalized to meet specific needs. ,, However, though their synthesis appears trivial, separating the CDs from their synthesis solutions is a significant challenge due to their high solubility, making it inconvenient for their storage, transport, and use in other reaction media. Usually, their separation involves dialysis or column chromatography, which is time- and solvent-consuming and not easily scalable to restrain their commercialization prospects. − Besides, it is a common experience that a small fraction of the reactants convert to “well-behaved” CDs, the remaining becoming discarded.…”