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Boosting the photocatalytic ability of g-C3N4 for hydrogen production by Ti3C2 MXene quantum dots
摘要： The big challenging issues in photocatalytic H2 evolution are efficient separation of the photoinduced carriers, the stability of the catalyst, enhancing quantum efficiency and requiring photoinduced electrons enrich on photocatalysts’ surface. Herein, Ti3C2 MXene quantum dots (QDs) possess the activity of Pt as co-catalyst in promotion the photocatalytic H2 evolution to form heterostructure with g-C3N4 nanosheets (NSs) (denoted as g-C3N4@Ti3C2 QDs). The photocatalytic H2 evolution rate of g-C3N4@Ti3C2 QDs composite with an optimized Ti3C2 QDs loading amounts (100 mL) is nearly 26, 3 and 10 times higher than pristine g-C3N4 NSs, Pt/g-C3N4, Ti3C2 MXene sheet/g-C3N4, respectively. The Ti3C2 QDs increase the specific surface area of g-C3N4 and boost the density of active site. Besides, metallic Ti3C2 QDs possess excellent electronic conductivity, causing the improvement of carrier transfer efficiency.
关键词： Ti3C2 MXene quantum dots,Photocatalytic H2 production,g-C3N4 nanosheets,co-catalysts
更新于2025-09-19 17:13:59
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Biodegradable and Photostable Nb2C MXene Quantum Dots as Promising Nanofluorophores for Metal Ions Sensing and Fluorescence Imaging
摘要： Conventional fluorescent probes are either easily photobleached or non-biodegradable, which often leads to the unstable fluorescence signal output and long-term biological toxicity. Therefore, the development of novel fluorescent materials with both excellent photostability and biodegradability is of great significance for further broadening their application in numerous research fields. In this work, Nb2C quantum dots (Nb2C QDs) with pristine crystallographic structures of Nb2C MXene phases and surface oxygen-containing species are synthesized by an ultrasound assisted physicochemical exfoliation in tetrapropylammonium hydroxide. Detailed analyses indicate that the Nb2C QDs not only possess excellent chemical- and photo-stable fluorescence emission but also achieve successful application in fluorescence sensing of heavy metal ions and fluorescence imaging. More importantly, it is confirmed that the Nb2C QDs present high biocompatibility and unique biodegradation property responsive to human myeloperoxidase, implying the application safety of Nb2C QDs in vivo. Under the background of ever-growing and stringent requirements for biosafety and technical stability, the biocompatibility, biodegradability, and most importantly the promising fluorescence sensing/imaging characteristic of the obtained Nb2C QDs may argue well for their future applications in environmental monitoring, biomedical diagnosis, visual display, and anti-counterfeiting.
关键词： MXene quantum dots,biodegradation,fluorescent probes,fluorescence imaging,photobleaching resistance
更新于2025-09-16 10:30:52
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MXene Quantum Dot/Polymer Hybrid Structures with Tunable Electrical Conductance and Resistive Switching for Nonvolatile Memory Devices
摘要： Low-dimensional MXene materials including MXene quantum dots (MQDs) and nanosheets have attracted extensive attention owing to their unique structures and novel properties, but their most attractive features are still less explored than expected. A systematic study of the memory effects of MQD-based electronics is reported. Monodisperse MQDs are prepared by using a one-step facile hydrothermal synthetic method. By varying the MQD content in polyvinylpyrrolidone (PVP) hybrid composite films, the electrical conductance of an indium tin oxide (ITO)/MQD-PVP/gold (Au) sandwich structure can be tuned precisely from insulator behavior to irreversible resistive switching, reversible resistive switching, and conductor behavior. These irreversible and reversible resistive switches are capable of exhibiting write-once-read-many times (WORM) and flash memory effects, respectively. Both types of devices operate stably under retention testing, with a high on/off current ratio up to 100. The tunable memory and transient features of these hybrid films are likely due to MQD charge trapping due to their quantum confinement and dissolvability of memristive components. The results suggest that MXene nanomaterials are promising as resistive switching trigger for emerging nonvolatile memories for data storage, specially data storage security.
关键词： resistive switching,MXene quantum dots,charge trapping,flash memory,nonvolatile memory,write-once-read-many memory
更新于2025-09-12 10:27:22
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ε-Poly-L-lysine-protected Ti3C2 MXene quantum dots with high quantum yield for fluorometric determination of cytochrome c and trypsin
摘要： Titanium carbide quantum dots functionalized with ε-poly-L-lysine (PLL) were synthesized by sonication cutting and hydrothermal synthesis. The deprotonated Ti3C2 MXene quantum dots (Ti3C2 MQDs) exhibit excitation wavelength-dependent blue photoluminescence with typical excitation/emission peaks at 330/415 nm and a quantum yield of 22% due to strong quantum confinement. The fluorescence of ε-poly-L-lysine protected Ti3C2 MQDs (PLL-protected Ti3C2 MQDs) is reduced via an inner filter effect after the addition of cytochrome c (cyt-c). Response to cyt-c is linear in the 0.2 to 40 μM concentration range and the detection limit is 20.5 nM. In the presence of trypsin, cyt-c is hydrolyzed to small peptides, and the Fe3+ ion in cyt-c probably is reduced to Fe2+ with the aid of the digestive enzyme. This results in the restoration of the blue fluorescence of the modified MQDs. Fluorescence increases linearly in the 0.5 to 80 μg mL?1 trypsin concentration range with the detection limit of 0.1 μg mL?1. The method was successfully applied to the determination of cyt-c and trypsin in spiked serum samples.
关键词： Hydrothermal method,Inner filter effect,Fluorescence,Trypsin,Cytochrome c,Ti3C2 MXene quantum dots
更新于2025-09-12 10:27:22