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Nanotechnology is considered as an emerging effective means to augment plant photosynthesis. However, there is still a lot of work to be done in this field. Here, we applied the upconversion nanoparticles (UCNPs) on lettuce leaves and found that the UCNPs were able to transport into the lettuce body and colocalize with the chloroplasts. It was proved that UCNPs could harvest the near-infrared light of sunlight and increase the electron transfer rate in the photosynthesis process, thus increasing the photosynthesis rate. The gene expression analysis showed that more than 90% of gene expression in photosynthesis was upregulated. After spraying the UCNP solution on the leaves of lettuce and placing the lettuce under sunlight for 1 week, the wet/dry weight of the leaves increased by 53.33% and 45.71%, respectively. This nanoengineering of light-harvesting UCNPs may have great potential for applications in agriculture.

High-quality CsPbBr3 QDs were regulated to be precipitated in borosilicate glass by introducing a network modifier, CaF2, and the roles of Ca ions and F ions on the nucleation/growth of CsPbBr3 QDs in glass were revealed.

A rapid construction strategy is reported to achieve the composite structure of NaYF4:Yb,Er and carbon dots (CDs) through electrostatic interactions.

As one of the most promising fluorescent nanomaterials, carbon dots (CDs) have been extensively studied for their fluorescent properties in solution. However, research on the synthesis of multicolor solid-state fluorescence (SSF) CDs (from blue to red) is rarely reported. Herein, we used o-phenylenediamine, m-phenylenediamine and p-phenylenediamine with dithiosalicylic acid (DTSA) in the solvothermal reaction using acetic acid as a solvent to obtain aggregation-induced emissive (AIE) CDs of red (620 nm), green (520 nm), and blue (478 nm), respectively. XPS spectra and TEM image show that with the red-shift of luminescence, the particle size and content of C = O of the CDs gradually increases. Finally, based on the non-matrix solid-state multicolor luminescence characteristics of CDs, the application of white light LED devices is realized. Besides, based on the fat-soluble properties of CDs, fingerprint detection applications are realized.

Room-temperature afterglow (RTA) materials with long lifetime have shown tremendous application prospects in many fields. However, there is no general design strategy to construct near-infrared (NIR)-excited multicolor RTA materials. Herein, we report a universal approach based on the efficient radiative energy transfer that supports the reabsorption from upconversion materials (UMs) to carbon dots-based RTA materials (CDAMs). Thus, the afterglow emission (blue, cyan, green, and orange) of various CDAMs can be activated by UMs under the NIR continuous-wave laser excitation. The efficient radiative energy transfer ensured the persistent multicolor afterglow up to 7 s, 6 s, 5 s, and 0.5 s by naked eyes, respectively. Given the unusual afterglow properties, we demonstrated preliminary applications in fingerprint recognition and information security. This work provides a new avenue for the activation of NIR-excited afterglow in CDAMs and will greatly expand the applications of RTA materials.

Room-temperature phosphorescence (RTP) with carbon dots (CDs) can be exploited further if the mechanism of trap-state-mediated triplet-state energy transfer is understood and controlled. Herein, we developed an in situ calcination method for the preparation of a CDs@ZnAl2O4 composite material that exhibits unique UV and visible light-excitable ultra-broad-band RTP. The ZnAl2O4 matrix can protect the triplet emissions of CDs by the confinement effect and spin-orbit coupling. In addition, benefitting from the efficient energy transfer between the inorganic trap state and the triplet state of CDs, the special yellow to red RTP of CDs@ZnAl2O4 composites can be realized. A slow-decaying phosphorescence at 570 nm with a lifetime of 1.05 s and a fast-decaying phosphorescence at 400 nm with a lifetime of 0.41 s were observed with UV irradiation of 290 nm, which originated from the surface and core triplet states of CDs, respectively. Based on the unique RTP performance, anti-counterfeiting and information encryption were successfully realized using the CDs@ZnAl2O4 composites with LED light or UV light.

Carbon dots (CDs) have aroused widespread interest in the construction of room-temperature phosphorescent (RTP) materials. However, it is a great challenge to obtain simultaneous multicolor long-wavelength RTP emission and excellent stability in CD-based RTP materials. Herein, a novel and universal "CDs-in-YOHF" strategy is proposed to generate multicolor and long-wavelength RTP by confining various CDs in the Y(OH)

Biomass is a major resource for the preparation of carbon dots (CDs) and improving the production yield of CDs is a challenge. Herein, we select corn cobs as cheap, abundant, and renewable biomass to prepare CDs with a production yield as high as 55%. Through studying the main components (cellulose, hemicellulose, and lignin) of a corn cob, we determine that such a high yield is derived from the high content of hemicellulose and extremely low lignin content of the corn cob. This indicates that hemicellulose is beneficial to the formation of CDs during the hydrothermal process, while cellulose and hemicellulose are not. This mechanism is further verified using four other biomass sources (linen stalks, coir fibres, peanut shells, and bamboos) with different cellulose, hemicellulose, and lignin contents. Based on fluorescence quenching, the prepared CDs display excellent feasibility for Fe3+ selective detection with a good linear correlation ranging from 0 to 120 μM. This work reveals the effects of cellulose, hemicellulose, and lignin biomass on CDs thus providing a novel strategy for the selection of a precursor and large-scale preparation of CDs, laying the groundwork for the industrial synthesis and application of CDs.

Recently, researchers are no longer satisfied with the investigation of the fluorescence properties of carbon dots (CDs), but instead focus on the more attractive afterglow luminescence, especially room temperature phosphorescence (RTP) and thermal activation delayed fluorescence (TADF). Numerous attempts have been made to construct CD-based afterglow materials, including embed CDs in various rigid matrices or construct self-protective structures. Because of the diversity of construction methodologies, different mechanisms and effects would be produced, thus resulting in distinguishing afterglow characteristics. Afterglow of CDs in organic matrices is mainly due to the formation of hydrogen bonds, which can suppress intramolecular vibration and stabilize triplet states, thus generating afterglow emission. Afterglow of CDs in diverse inorganic matrices are completely different because the multifarious interactions between CDs and different matrices are generated (e.g., rigid structure covalent bonds, structural confinement, energy transform, etc). The self-protective CDs always possess polymer-like structure or polymer-chains on their surface, which can act as rigid matrix to activating afterglow emission. This review aims to sum up the relationships between structure construction and afterglow characteristics, and the mechanism of afterglow generation, which are of great significance for stimulating more exciting progress in the purposeful design of afterglow materials.

Abiotic stress severely threatens agriculture. Herein, we studied the effect of heteroatom-free carbon dots (CDs) on the alleviation of abiotic stresses in rice for the first time. During in vitro coincubation, suspended rice cells were exposed to 2,4-dichlorophenoxyacetate sodium (2,4-D-Na, 30 μg mL-1), 2,4-dichlorophenoxyacetic acid (2,4-D, 5 μg mL-1), NaCl (0.15 mol·L-1), and high light (2000 Lux), both with and without CDs (100 μg mL-1). After a week, CDs significantly reduced the inhibition rate of 2,4-D-Na on the rice cell biomass from 48.16 to 27.44% and increased the biomass of rice cells exposed to 2,4-D, NaCl, and high light, by 4.12, 1.10, and 4.01 times that of the control (pure nutrient medium), respectively. Furthermore, the growth of CD-germinated rice seedlings was not obviously affected by 2,4-D-Na, 2,4-D, and NaCl. Further results showed that the CDs demonstrated an intrinsic free-radical scavenging property and could increase the peroxidase activity and the contents of phenolics and flavonoids in rice by 125.81, 39.60, and 47.63%, respectively. Furthermore, CDs improved the nutrient assimilation of rice cells under 2,4-D stress by 14.69%. With higher antioxidant capacity and sufficient nutrients, the CD-treated rice showed excellent resistance to abiotic stresses. This study suggested the great potential of CDs in protecting crops against abiotic stress.

In recent years, the application of nanomaterials in promoting plant growth and augmenting photosynthesis has aroused great interest. Herein, carbon dots (CDs) are combined with NaYF4:Yb,Er to achi...

Sunlight utilization by plants via the photosynthesis process is limited to the visible spectral range. How to expand the utilization spectral range via construction of a hybrid photosynthetic system is a hot topic in this field. In this work, far-red carbon dots (FR-CDs) with excellent water solubility, good biocompatibility, high quantum yield (QY), and superior stability were prepared by a one-step microwave synthesis in 3 min. The as-prepared FR-CDs is an efficient converter transferring ultraviolet A (UV-A) light to 625-800 nm far-red emission, which can be directly absorbed and utilized by chloroplasts. Due to the broader spectral utilization of solar energy and Emerson effect, increased photosynthetic activity can be achieved both in vivo and in vitro when applied for Roman lettuce. The in vitro hybrid photosynthetic system via coating chloroplasts with FR-CDs presents higher electron transfer efficiency between PS II (photosystem II) to PS I (photosystem I), which consequently increases the ATP production. The in vivo experiment further confirms that FR-CDs-treated lettuce can induce a 28.00% higher electron transfer rate compared with the control group, which results in 51.14 and 24.60% enhancement of fresh and dry weights, respectively. This work is expected to provide a way for improving the conversion efficiency from solar energy to chemical energy. (PS II) to photosystem I (PS I), which consequently increases the ATP production. The in vivo experiment further confirms that FR-CDs-treated lettuce can induce a 28.00% higher electron transfer rate compared with the control group, which results in 51.14 and 24.60% enhancement of fresh and dry weights, respectively. This work is expected to provide a way for improving the conversion efficiency from solar energy to chemical energy.

By adopting an adhesive polyvinyl alcohol (PVA) to encapsulate fluorescent carbon dots (CDs), a novel approach to prolong foliar fluorescent CD retention for enhancing lettuce photosynthesis was de...

As one of the most promising fluorescent nanomaterials, the fluorescence of carbon dots (CDs) in solution is extensively studied. Nevertheless, the synthesis of multicolor solid-state fluorescence (SSF) CDs is rarely reported. Herein, CDs with multicolor aggregation-induced emission are prepared using amine molecules, all of them exhibiting dual fluorescence emission at 480 nm (Em-1) and 580-620 nm (Em-2), which is related to the SS bonds of dithiosalicylic acid and the conjugated structure attached to CO/CN bonds, respectively. As a strong electron-withdrawing group, the increase of CN content makes dual-fluorescent groups on the surface of CDs produce push and pull electrons, which determines intramolecular charge transfer (ICT) between the double emission. With the increase in CN content from 35.6% to 58.4%, the ICT efficiency increases from 8.71% to 45.94%, changing the fluorescence of CDs from green to red. The increase of ICT efficiency causes fluorescence quantum yield enhancement by nearly five times and redshift of the fluorescence peak. Finally, based on the multicolor luminescence properties induced by the aggregation of CDs, pattern encryption and white-LED devices are realized. Based on the fat solubility and strong ultraviolet absorption characteristics of CDs, fingerprint detection and leaf anti-UV hazards are applied.

Stimuli-responsive shape-memory materials are a category of fascinating smart materials, which undergo reversible shape transformation with environmental changes. Among a large number of stimuli-responsive shape-memory materials, light-driven materials have sparked tremendous attention because of their stability, remote operability and environmentally friendly. Herein, we report a novel strategy for the synthesis of a light-responsive shape-memory polymer that is made from carbon dots and polyvinyl alcohol. The as-prepared carbon dots are endowed with good visible light absorption and excellent photothermal conversion, which enable the carbon dot/polyvinyl alcohol composite polymer to serve as a light-responsive shape-memory polymer. The carbon dots not only work as photothermal agents but also offer additional hydrogen bond interaction, which accelerates the shape-memory recovery rate. The results show that the composite polymer can realize shape recovery using relatively low laser power. Most importantly, the as-prepared carbon dot/polyvinyl alcohol composite polymer not only possesses great research potential in different types of fields, such as medical and sensing, but also provides a effective and economic strategy for taking the advantage of light.

Carbon dots (CDs), a novel member of the renowned carbon-based nanomaterials family, have gained tremendous attention in various fields. Their extraordinary properties, including facile synthesis procedure, photoluminescence, biocompatibility, tunable surface functionalities, water solubility and low toxicity, have introduced them extensively in biological applications, such as bioimaging, biosensing, photocatalysis and molecule delivery. Recently, CDs have attracted significant interest in agriculture to improve the growth and production of plants and great progress has been achieved in this area. Here, we will review the interactions of CDs with plant systems for the first time, including symptomatic plant growth, internal physiological processes and other external factors involved in plant growth. Furthermore, the current challenges and future perspective of CDs in the field of agriculture are discussed. Looking forward, it indicates that CDs might play an important role in the future of agriculture.

Embedding CsPbBr3 quantum dots (QDs) in inorganic glasses via in situ crystallization has been regarded as a feasible strategy to improve their stability due to the protecting role of the robust glass matrix. However, the influence of the rigidity of the glass network structure on CsPbBr3 crystallization is rarely reported. Herein, we report an approach to control the rigidity of the glass network structure through substituting the [GeO4] tetrahedron with the [SiO4] tetrahedron in mother glass, which allows fine-tuning of the morphology and luminescence properties of CsPbBr3 QDs. The water-resistance of CsPbBr3 QD glass (CsPbBr3 QD@glass) is clearly enhanced by increasing the content of the [SiO4] tetrahedron, while the size of CsPbBr3 nanocrystals decreases gradually and the corresponding quantum efficiency decreases. Moreover, the thermostability and photostability of CsPbBr3 QD@glasses were also studied systematically. The correlation between the rigidity of the glass network structure and the local microenvironment of the crystallization of CsPbBr3 QDs is revealed. Our results provide a reference for the design of mother glass to obtain perovskite QDs with high quantum efficiency and high stability based on the rigidity of the glass network.

As one of the key elements of indoor agriculture, horticultural light sources are developing rapidly towards requiring high energy density, high output power and high stability, which poses a challenge for traditional phosphor conversion devices. To address this, an all-inorganic blue-red dual-emitting light convertor consisting of Ba1.3Sr1.7MgSi2O8:Eu2+,Mn2+ (BSMS) phosphor-in-glass (PiG) plates was prepared to improve the duration lifetime of converted high-power light-emitting diodes (LEDs) and meet the light quality requirements of photosynthesis for indoor agriculture. The obtained samples show an external quantum efficiency of 45.3%, outstanding thermal stability and a specific emission spectrum that highly matches the absorption of chlorophyll and β-carotene. Moreover, a proof-of-concept BSMS-PiG horticultural lamp for application in an indoor plant factory was successfully fabricated based on a ∼370 nm emitting LED chip. The blue-red ratio of its spectrum could be regulated by controlling the thickness of BSMS-PiG and the concentrations of Mn2+ ions within BSMS-PiG. The BSMS-PiG horticultural LEDs were applied to the indoor cultivation of Romaine lettuce. The results indicated that the biomass of Romaine lettuce was 58.21% greater than that of control lettuce samples cultivated under commercial plant lamps. In particular, the content values of total chlorophyll, β-carotene and soluble protein were improved. The BSMS-PiG horticultural LED is a potential candidate to act as a high-power horticultural light source.

Biogenic amines (BAs) from rotten food cause serious harm to sensitive people. Therefore, the development of a smart label that can intuitively monitor the degree of food decay in real-time is of great significance in food safety. Herein, we report the synthesis of pH-responsive carbon dots with red emission (R-CDs) by the solvothermal treatment of citric acid and urea. The fluorescence intensity of R-CDs gradually increased as the pH of the solution increased from 1 to 12. We studied the mechanisms of pH response and found that H-aggregation occurred when R-CDs were in acidic solution and caused quenching; when they were distributed in alkaline solution, the Fermi level shift caused reduced self-absorption and enhanced red fluorescence emission. The intense red emission of R-CDs is beneficial for the visual detection of alkaline organic amines and BAs derived from rotten shrimp to achieve food safety detection. Moreover, the R-CDs can be used as a promising pH-sensitive fluorescent ink, which has broad prospects and significance in anticounterfeiting and information encryption.

As emerging carbon materials, carbon dots (CDs) have received extensive attention in recent years. Since CDs have excellent optical properties, most reports on carbon dots focus on research of their optical applications. However, their diverse surface functional groups also afford broad application prospects in chemical engineering. This review article focuses on the research progress in the chemical applications of CDs in the following three aspects: CDs used as structural regulators of the morphology and size of materials; CDs used as chemical additives, such as consolidant, antirust, antifreeze, lubricant, and scale inhibitors; CDs used as reinforcing reagents to improve water dispersibility and enhance mechanical properties of materials. Finally, we focus on existing problems in this field and look forward in the direction of future development.

C-Dots and composites based on them face the challenges of poor stability, especially under photo-radiation, and low solid-state photoluminescence quantum yields (PLQYs), which hinder their application in optical devices. Herein, a novel 2-dimensional hybrid material of polysiloxane embedded with Si-doped carbon dots (P-E-Si-CDs) was synthesized by a self-assembly approach, and the hybrid composite exhibited broadband blue-green fluorescence emission, outstanding photostability, high thermal stability, and a high PLQY of 82.8%. Moreover, the dual fluorescent emissions were demonstrated the creation of two closed-loop fluorophores. Using the as-prepared hybrid fluorescent material, fabricated light-emitting diodes (LEDs) based on UV and blue-emitting LED chips present safe warm white light emission and adjustable white emission with a high color rendering index of up to 91, respectively. This work provides a novel strategy for the design and realization of Si-CD-based hybrid composites, thus promising their prospective use commercially in LED lighting.

Afterglow including thermally activated delayed fluorescence (TADF) and room-temperature phosphorescence (RTP) has stimulated considerable attention owing to bright potential applications in optoelectronic devices, sensing, and security systems. However, previously reported afterglow materials are mostly single-mode (one of RTP or TADF only), a tunable multi-mode afterglow emission is still rarely achieved. Herein, we report the temperature-responsive conversion characteristics of TADF and RTP of carbon dots in silica (CDs@SiO2) for the first time. The unique temperature-responsive afterglow characteristics, that is, phosphorescence and TADF can be mutually transformed as the temperature changes, resulting in the free conversion of the RTP/TADF ratio as well as the afterglow color change through simple temperature control. The Si–O network plays multiple roles to strengthen and confine the embedded CDs, thus resulting in ultralong RTP emission and unique afterglow characteristics. Furthermore, CDs@SiO2 exhibited excellent stability against water, acid, alkali, salt and oxidants as well as polar solvents. CDs@SiO2 with unique afterglow characteristics and high stability can have multiple potential applications in rapid fingerprint detection and temperature sensing, especially in advanced temperature-responsive multicolor anti-counterfeiting and encryption.

Compared to fluorescence imaging with short-lived emissive probes, the use of phosphorescent probes conveys the advantage of long signal persistance in time and this permits one to discriminate aga...

Herein, we present a simple strategy to enhance the stability of water-sensitive SrLiAl3N4:Eu2+ phosphor through embedding the phosphor particles into low-melting Sn-P-F-O glass using phosphor-in-glass (PiG) approach. After being immersed in water for 96 h, the emission intensity of the SrLiAl3N4:Eu2+-PiG sample was maintained at 80% of its pristine intensity, indicating the moisture-resistance property of SrLiAl3N4:Eu2+ was significantly enhanced. Employing the narrow-band red-emitting SrLiAl3N4:Eu2+-PiG sample and a blue COB (chip-on-board), a plant growing LED device was fabricated. The emission spectrum of the device matches well with the absorption of Chlorophyl (a and b) in plants, indicating the as-prepared SrLiAl3N4:Eu2+-PiG are suitable to be applied in plant lighting field. We believe that this simple method reported in this communication can be easily expanded to other water-sensitive luminescence materials.

The combination of carbon dots (CDs) and rare-earth ions has attracted increasing attention due to their unique fluorescence properties. Herein, CDs are incorporated with NaYF4:Eu to form stable NaYF4:Eu@CDs nanocomposites by a simple sol-gel route. It has been demonstrated that CDs are successfully embedded in the silica layer outside NaYF4:Eu nanoparticles. These nanocomposites exhibit characteristic emissions of both CDs and NaYF4:Eu under a single excitation wavelength. By using their dual-emissive properties, the nanocomposites can act as ratiometric fluorescent sensor for selective detection of Fe3+ ions in the range of 0–350 μM. The temperature-dependent luminescent property of the nanocomposites makes them also suitable as thermometers in the range from 377 to 467 K. In addition, the luminescent color can be regularly adjusted by tuning the mass ratio of NaYF4:Eu to CDs. This combing strategy enables us to achieve dual emission of CDs and Eu3+ ions in nanocrystals, opening an avenue towards multifunctional applications in widespread fields.

Carbon dots (CDs) have attracted attention in metal-free afterglow materials, but most CDs were heteroatom-containing and the afterglow emissions are still limited to the short-wavelength region. A universal approach to activate the room-temperature phosphorescence (RTP) of both heteroatom-free and heteroatom-containing CDs was developed by one-step heat treatment of CDs and boric acid (BA). The introduction of an electron-withdrawing boron atom in composites can greatly reduce the energy gap between the singlet and triplet state; the formed glassy state can effectively protect the excited triplet states of CDs from nonradiative deactivation. A universal host for embedding CDs to achieve long-lifetime and multi-color (blue, green, green-yellow and orange) RTP via a low cost, quick and facile process was developed. Based on their distinctive RTP performances, the applications of these CD-based RTP materials in information encryption and decryption are also proposed and demonstrated.

A kind of optical oxygen sensing material was obtained in a simple and low-cost method via assembling water-soluble silicon nanoparticles (Si NPs) into the well-ordered channel of SBA-15. The system we had developed showed high selectivity and sensitivity to oxygen which was attributed to large pore sizes and high surface-to-volume ratios of SBA-15. The fluorescence intensities of the samples were recorded under different oxygen volume fractions. By analyzing experimental data, we found the samples had little response to carbon dioxide. The fluorescence intensity decreased prominently as oxygen volume fractions transformed from 0 to 100%. These results indicated that the SBA-15/Si NPs composites had superior properties for oxygen sensing and would provide broad application prospects in oxygen sensing or catalyst.

Room-temperature phosphorescence (RTP) with carbon dots (CDs) can be exploited further if the mechanism of trap-state-mediated triplet-state energy transfer is understood and controlled. Herein, we developed an in situ calcination method for the preparation of a CDs@ZnAl

The mechanism of the solvation-dependent multicolor luminescence of carbon dots (CDs) is not clear, despite the fact that multicolor luminescent CDs have important applications in many fields. In this article, we report solvated chromogenic CDs with productivity of up to 57%. The luminescence of the CD particles exhibits a regular redshift in N,N-dimethylformamide (DMF), ethanol, water, and acetic acid. The redshift of the CDs may be ascribed to the linking of the CD surfaces to the solvent through hydrogen bonds (HB). Different surface level states are formed by HB between the surfaces of the CDs and the solvent, and differences in dispersion states lead to different energy resonance transfer (ETR) efficiencies. The CDs/B2O3 composite exhibits excellent fluorescence thermal stability, and it has also been used to manufacture white-light-emitting devices with a high color rendering index of 87. Additionally, the excellent solvation effects of the CDs have application prospects in the detection of the water content in organic solvents. Finally, the CDs are used to realize cell imaging and positioning, which has significant application prospects in biological fields.

C-dot-based composites with phosphorescence have been widely reported due to their attractive potential in various applications. But easy quenching of phosphorescence induced by oxygen or instability of matrices remained a tricky problem. Herein, we reported a Si-doped-CD (Si-CD)-based RTP materials with long lifetime by embedding Si-CDs in sulfate crystalline matrices. The resultant Si-CD@sulfate composites exhibited a long lifetime up to 1.07 s, and outstanding stability under various ambient conditions. The intriguing RTP phenomenon was attributed to the C = O bond and the doping of Si element due to the fact that sulfates could effectively stabilize the triplet states of Si-CDs, thus enabling the intersystem crossing (ISC). Meanwhile, we confirmed that the ISC process and phosphorescence emission could be effectively regulated based on the heavy atom effect. This research introduced a new perspective to develop materials with regulated RTP performance and high stability.

Abiotic stress severely threatens agriculture. Herein, we studied the effect of heteroatom-free carbon dots (CDs) on the alleviation of abiotic stresses in rice for the first time. During in vitro coincubation, suspended rice cells were exposed to 2,4-dichlorophenoxyacetate sodium (2,4-D-Na, 30 μg mL