This study details the synthesis and characterization of phosphorus-sulfur co-doped graphitic carbon nitride quantum dots (PSQ) and their integration into g-C3N4 (CN) to form PSQ/CN composites for the enhanced photocatalytic reduction of Cr(VI) and fluorescence detection. Incorporating PSQ into CN was found to significantly improve light absorption, narrow the band gap, and enhance charge separation efficiency. Notably, the composite material exhibits superior photocatalytic performance, especially in acidic environments. Photocatalytic assessments utilizing Cr(VI) demonstrated that the PSQ/ CN composite outperformed both undoped and singly doped materials, indicating its superior photocatalytic activity. Additionally, phosphorus-sulfur co-doping markedly increased the fluorescence quantum yield of PSQ. The fluorescence intensity exhibited a linear decrease with increasing Cr(VI) concentrations, enabling sensitive and selective detection of Cr(VI) with a detection limit as low as 1.69 μmol/L. Collectively, the PSQ/CN composite and PSQ highlight their potential for photocatalysis and fluorescence-based detection of Cr(VI), providing high sensitivity, selectivity, and synergistic interactions within the composite material.

Quantum dot nanocomposite-based luminescent materials have gained attention for solid-state lighting and optical displays. This study presents a one-step, eco-friendly hydrothermal process to synthesize nitrogen, potassium, and calcium-doped carbon quantum dots (N, K, Ca-doped CQDs) from the flower extract of Mesembryanthemum crystallinum L. (ice plant). The CQDs were characterized using HRTEM, EDX, SAED, XPS, XRD, NMR, FTIR, zeta potential, UV–Vis, and photoluminescence spectroscopy. HRTEM revealed an average particle size of 4.6 nm, with a range of 2 to 7 nm. The CQDs exhibited a quantum yield of 20%, excellent water solubility, photostability, and greenish fluorescence under UV (365 nm). The fluorescence spectra were analyzed using CIE (Commission Internationale de l’Eclairage) chromaticity coordinates to determine the emitted color. The fluorescence emission behavior was influenced by solvent polarity, locally excited (LE) states, intramolecular charge transfer (ICT) processes, and hydrogen bonding. The hydrogen bonds between N, K, Ca-doped CQDs and DI water likely enhanced the stability of the ICT state, resulting in a red shift in fluorescence. Additionally, we developed an eco-friendly wheat-starch-based bioplastic nanocomposite by embedding the CQDs. The effects of CQD concentration and pH sensitivity on luminescent properties were explored. Finally, we demonstrated a practical application by designing a conceptual nameplate-like calligraphy using the optimized CQDs@bioplastic nanocomposite film (CQD concentration: 240 mg/mL, pH: 2.7), highlighting its potential for luminescent film applications.

This study incorporates the formation of carbon quantum dots (CQDs) via a hydrothermal approach, recording the first-time use of castor leaves as a natural precursor. The used precursor offers various benefits including novelty, abundance, elemental composition, and biocompatibility. CQDs were further characterized with multiple techniques including high-resolution transmission electron microscope (HR-TEM), X-ray photoelectron microscopy (XPS), X-ray diffraction (XRD), Fouriertransform infrared spectroscopy (FTIR), Raman spectroscopy, UV–visible spectroscopy, Zeta analysis, and optical spectroscopy. They are fundamentally composed of carbon (71.37%), nitrogen (3.91%), and oxygen (24.73%) and are nearly spherical, and uniformly distributed with an average diameter of 2.7 nm. They possess numerous interesting characteristics like broad excitation/emission bands, excitation-sensitive emission, marvelous photostability, reactivity, thermo-sensitivity, etc. A temperature sensor (thermal sensitivity of 0.58% C− 1) with repeatability and reversibility of results is also demonstrated. Additionally, they were found selective and sensitive to ions in aqueous solutions. So, they are also utilized as a fluorescent probe for metal ion ( Fe3+) sensing. The lowest limit of detection (LOD) value for the current metal ion sensor is 19.1 μM/L.

Graphene quantum dots have recently gained significant attention for their potential application in the development of optoelectronic materials. The present study focused on the ultrasonic method to synthesize white-light-emitting graphene quantum dots from coal soot in just 2 min at room temperature. The white-light emission was achieved in solution and polymeric film with good Commission Internationale del’Eclairage index (0.28, 0.33) and (0.25, 0.30), respectively. The graphene quantum dots cover a significant fraction of the visible region in the emission spectrum with two prominent bands at 475 and 635 nm at 380 nm photoexcitation, corresponding to monomer and J-aggregate emission. The strong reducing and basic nature of the ethylene diamine facilitated the preparation of self-assembled J-aggregate graphene quantum dots through hydrogen bonding and electrostatic interaction. The mechanism of origin J-aggregate emission in the prepared graphene quantum dots was studied using UV–visible absorption, steady-state, lifetime fluorescence spectroscopy, and zeta potential. The as-synthesized graphene quantum dots are successfully coated on the UV-LEDs' surface and emit white light on the applied voltage. The colours of red, green, blue, and yellow balls appear significantly in the lighting of prepared white LEDs.

Due to the sturdy photoluminescence and absorption, CQDs emerged as a suitable candidate for optical sensing probe. The present study deals with the synthesis of blue-fluorescent Carbon Quantum Dot (TAA-CQD) using tannic acid and glycine as novel precursors. The TAA-CQD were synthesised hydrothermally with the high production yield and QY to be 86.12 and 21%, respectively, and an average particle size of 1.9 nm. The TAA-CQD aqueous solution displays excitation-dependent fluorescence emission in the excited range from 420 to 650 nm. The CIE co-ordinates in a highly blue region at (0.14, 0.19) confirmed the synthesised TAA-CQD were blue in fluorescent. Fluorescence of TAA-CQD was stable under all pH range, resisted the high ionic strengths condition and stable over 8 months. Furthermore, the fluorescent TAA-CQD was capable in detecting a tetracycline-classed antibiotic Doxycycline (DXY) along with remarkable selectivity and sensitivity. The measures limit of detection (LOD) was very low 2.42 mM in comparison to other methods. Moreover, the applicability of the proposed work has been fruitfully employed on the pharmaceutical waste. Thus, our designed TAA-CQD based fluorescence sensing system hold great promise for the advanced sensing materials in the detection of DXY and we believe that our approach will be promising and viable in a clinical applications.

Ibuprofen (IBU), a common pharmaceutical and personal care product (PPCP), is a pervasive water pollutant with adverse ecological and human health effects after transformation and accumulation. In this study, we synthesized Fe, N-doped carbon quantum dots (Fe, N-CQDs) using pig blood and FeCl3 as a precursor via a one-step hydrothermal method. TEM, XRD, XPS, and UV–Vis were used to characterize the physical and chemical properties of Fe, N-CQDs. We investigated the feasibility of Fe, N-CQDs in activating peroxymonosulfate (PMS) for IBU degradation under visible light. The experimental results revealed that Fe in Fe, N-CQDs predominantly formed a stable complex through Fe–N and Fe-OH, with a high degree of graphitization and a sp2- hybridized graphitic phase conjugate structure. The Fe, N-CQDs/Light/PMS system exhibited strong activity, degrading over 87% of IBU, maintaining a wide pH range (3–10) adaptability. Notably, Fe, N-CQDs acted as visible-light catalysts, promoting Fe3+/ Fe2+ cycling and PMS activation, generating both free radicals ( SO4 •–, ·OH) and non-radicals (1O2, h+) to effectively degrade IBU. This study presents an innovative approach for the sustainable utilization of pig blood as a biomass precursor to synthesize Fe- and N-doped carbon materials. This study provides a new approach for the sustainable and value-added utilization of natural wastes and biomass precursors of Fe- and N-doped carbon materials, which can be used to treat pollutants in water while treating discarded pig blood.

In this study, high-efficiency InZnP/ZnSe/ZnS quantum dots (QDs) were synthesized and applied to the development of self-luminous traffic signs. The synthesized QDs exhibited a photoluminescence (PL) peak wavelength of 613 nm and a uniform nanoparticle size of 6 nm in diameter. Quantum dot films were coated using a roll-to-roll process with varying thicknesses (110 μm, 85 μm, and 75 μm), and color coordinate analysis confirmed that all films fell within the red region. A 4CL resin and PCB with high thermal dissipation properties were employed to fabricate the self-luminous traffic signs. Performance evaluations showed a white luminance of 625.4 cd/㎡, a red luminance of 220.2 cd/㎡, an insulation resistance of 10,000 MΩ, and an insulation breakdown voltage of 500V, indicating excellent performance. This study confirms the potential of InZnP-based QDs as an environmentally friendly alternative to conventional Cd-based QDs. Furthermore, the integration of high-efficiency QD films with advanced heat-dissipating PCB technology is expected to improve traffic safety, particularly in low-visibility and nighttime environments

This study aims to develop an AI-based analysis system that aligns with the international trend of AI legislation, including the EU's AI Act, while also addressing the analytical needs of the public sector. The focus is on providing timely and objective information to policymakers and specialized researchers by exploring advanced analytical methodologies. As the complexity and volume of data rapidly increase in the modern policy environment, these methods have become essential for governments to obtain the objective information needed for critical decision-making. To achieve this, the study integrates machine learning, natural language processing (NLP), and Large Language Models (LLM) to create a system capable of meeting the analytical demands of government entities. The target dataset consists of “quantum” field data collected from South Korea's National R&D Information System (NTIS). Machine learning was applied to this data to assess the validity of the analysis, while BERTopic, a natural language analysis package, was used for text analysis. With the introduction of LLMs, the extracted information from machine learning and natural language analysis was not merely listed but also connected in meaningful ways to provide policy insights. This approach enhanced the transparency and reliability of AI analysis, minimizing potential errors or distortions in the data analysis process. In conclusion, this study emphasizes the development of a system that enables rapid and accurate information provision while maintaining compatibility with international AI regulations such as the AI Act. The use of LLMs, in particular, contributed to enhancing the system’s capabilities for deeper and more multifaceted analysis.

Truss structures, widely used in engineering, consist of straight members transferring axial forces. Traditional analysis methods like FEM and the Force Method become computationally expensive for large-scale and nonlinear problems. Surrogate models using Artificial Neural Networks (ANNs), particularly Physics-Informed Neural Networks (PINNs), offer alternatives but require extensive training data and computational resources. Variational Quantum Algorithms (VQAs) address these challenges by leveraging quantum circuits for optimization with fewer parameters. Variational Quantum Circuits (VQCs) based on Quantum Neural Networks (QNNs) utilize quantum entanglement and superposition to approximate high-dimensional data efficiently, making them suitable for computationally intensive tasks like surrogate modeling in structural analysis. This study applies QNNs to truss analysis using 6-bar and 10-bar planar trusses, assessing their feasibility. Results indicate that residual-based loss functions enable QNNs to make reliable predictions, with increased layers improving accuracy and a higher Q-bit count contributing to performance, albeit marginally.

Lithium-ion batteries (LIBs) are widely used as essential power sources for electric vehicles and energy storage systems. Among various cathode materials, Li[Ni0.9Mn0.1]O2 (NM90) has gained significant attention for enhancing the performance of LIBs due to its high energy density and nontoxicity. However, increasing the nickel content introduces challenges, including structural instability and cation mixing. To address these issues, we propose a surface coating strategy using nitrogendoped carbon quantum dots (NCQDs). NCQDs provide high electrical conductivity and electrochemically active sites, so the NCQDs coating effectively enhanced both structural stability and electrical/ionic conductivity. The NCQDs were synthesized via a hydrothermal method, and NM90 were synthesized by co-precipitation. The fabricated NCQD/NM_5 electrode exhibited superior electrochemical properties, including a high initial capacity of 189.6 mAh/g, excellent rate performance, and an outstanding capacity retention of 81.5 % after 200 cycles in 1C. These superior results demonstrate that surface modification using the NCQDs strategy for Li[Ni0.9Mn0.1]O2 cathode materials will contribute to the further development of cycle stability and ultrafast performance in energy storage systems.

A simple and effective method was developed to prepare fluorescent carbon quantum dots (CQDs) for the detection of Fe3+ and Cu2+ in aqueous solution. The water-soluble CQDs with the diameter around 2–5 nm were synthesized using anthracite coal as the precursor. In addition, the as-prepared CQDs exhibits sensitive detection properties for Fe3+ and Cu2+ metal cations with a detection limit of 18.4 nM and 15.6 nM, respectively, indicating that the coal-derived CQDs sensor is superior for heavy metal recognition and environmental monitoring.

Carbon quantum dots (CQDs) are novel nanocarbon materials and widely used nanoparticles. They have gradually gained popularity in various fields due to their abundance, inexpensive cost, small size, ease of engineering, and distinct properties. To determine the antibacterial activity of metal-doped CQDs (metal-CQDs) containing Fe, Zn, Mn, Ni, and Co, we chose Staphylococcus aureus as a representative Gram-positive strain and Escherichia coli as a representative Gram-negative bacterial strain. Paper disc diffusion tests were conducted for the qualitative results, and a cell growth curve was drawn for quantitative results. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and IC50 were measured from cell growth curves. As a result, all of the metal-CQDs showed toxicity against both Gram-positive and Gram-negative bacteria. Furthermore, Gram-negative bacteria was vulnerable to metal-CQDs than Gram-positive bacteria. The toxicity differed concerning the type of metal-CQDs; Mn-CQDs exhibited the highest efficacy. Hence, this study suggested that CQDs can be used as new nanoparticles for antibiotics.

Fluorescent Carbon Quantum Dots (FCQDs), a new generation of carbon nanomaterials, have attracted a lot of attention throughout the years. This paper applied a straightforward and environmentally beneficial way to create water-soluble FCQDs hydrothermally from coconut shells. The as-prepared FCQDs have desirable functional groups and exhibit strong blue-emitting fluorescence with a relative quantum yield of 0.6 and 0.7%. The optical bandgap of FCQDs is calculated using UV–Vis spectra to be between 3.9 and 4.4 eV. Optical studies show that FCQDs have good fluorescence properties when excited at 360 nm. Whereas the fluorescence decay lifetime using TCSPC are 1.6–0.99 ns. The synthesized FCQDs were found by HRTEM to have a spherical shape and a particle-size distribution of 2.8–5.4 nm. As-prepared FCQDs has a very low hemotoxicity of 0.5 to 1.3%, which indicates that they have acceptable biocompatibility and are not hazardous. According to the DPPH antioxidant data, FCQDs had a stronger antioxidant activity compared to earlier reports. These important characteristics enable its applications in biomedical, food packaging, fluorescence imaging, photocatalysis, and sensing. The enhanced antioxidant characteristics of the produced FCQDs make them appropriate for use in biomedical, bioimaging, chemical, and industrial applications. The as-synthesized FCQDs were used for the detection of ferric ions with good selectivity.

Graphene shows unique electron-transport properties owing to the density of its carriers near the Dirac point. The quantum capacitance (CQ) of graphene is an intrinsic property that has been investigated theoretically in many previous studies. However, the development of CQ theory is hindered by the limited availability of related experimental works. In this perspective, experimental works on the CQ of mechanically exfoliated graphene, graphene synthesized by chemical vapor deposition (CVD), and graphene mesosponge are briefly summarized. The impact of structural properties such as stacking layers, defects, and nitrogen doping on CQ was experimentally investigated. Furthermore, the applicability of CQ theory was extended to three-dimensional graphene frameworks. Future research on CVD-synthesized and three-dimensional graphene is expected to enhance our comprehension of the underlying nature of CQ.

This study evaluated the changes in the quality characteristics of extracts (Quantum Energy) from Rehmannia glutinosa, ginseng, balloonflower, Poria cocos, and Adenophora stricta. The extracts were prepared through a six-day aging process, during which the pH decreased with a longer aging period while the viscosity and oBrix values were increased. The color difference (E) of the extracts ranged from 0.27 to 0.49 for all samples, indicating minimal color change with aging. The free sugar content was highest for fructose and glucose, while lactose was not detected. Furthermore, the total free sugar content ranged from 24.518 to 27.646 g/100 g, generally decreasing with the aging time. Benzo[a]pyrene in the extracts ranged from 0.040 to 0.074 g/kg, which is below the limit of quantification. In addition, all extracts were free of total aerobic bacteria, Escherichia coli, and coliforms, confirming that the aging method used in this study was microbiologically safe.

InP quantum dots (QDs) have attracted researchers’ interest due to their applicability in quantum dot light-emitting displays (QLED) or biomarkers for detecting cancers or viruses. The surface or interface control of InP QD core/ shell has substantially increased quantum efficiency, with a quantum yield of 100% reached by introducing HF to inhibit oxide generation. In this study, we focused on the control of bandgap energy of quantum dots by changing the Zn/(In+Zn) ratio in the In(Zn)P core. Zinc incorporation can change the photoluminescent light colors of green, yellow, orange, and red. Diluting a solution of as-synthesized QDs by more than 100 times did not show any quenching effects by the Förster resonance energy transfer phenomenon between neighboring QDs.

This study is about the optical properties of InP-based quantum dot nanoparticles depending on their core/shell structure. The need to synthesize non-cadmium-based quantum dot nanoparticles with high quantum efficiency has become necessary due to the harmful effects of the element cadmium. We synthesized three types of quantum dot nanoparticles in 2000ml three-necked flasks by varying the synthesis temperature and time to have the same PL spectra according to the composition of the core and shell. The PL spectra, absolute quantum efficiency, and nanoparticle size were compared and analyzed according to the composition at red emission wavelengths of 614, 616, and 630 nm. InP/ZnSe/ZnS nanoparticles were synthesized with the highest PL-AQY of 94% at 614 μm, and Ga-doped InP/GaP/ZnSe/ZnS nanoparticles were synthesized with the highest PL-AQY of 97% at 616 μm. InZnP/ZnSe/ZnS nanoparticles with alloy cores were able to synthesize quantum dot nanoparticles with a peak PL-AQY of 98% at 630μm.