Thioacetamide-derived nitrogen and sulfur co-doped carbon quantum dots for “green” quantum dot solar cells

Rapid, visual and autocatalytic quantifying Ag(I) and Fe(Ⅲ) by ratiometric fluorescence sensor of N, Si, S-GQDs/OPD

N, Si, S co-doped graphene quantum dots (N, Si, S-GQDs) were synthesized from waste toner and glutathione (GSH) via a one-pot hydrothermal method. Combined with o-phenylenediamine (OPD), a rapid, visual, and autocatalytic ratiometric fluorescence sensor of N, Si, S-GQDs/OPD was fabricated for detecting Ag(I) and Fe(III) ions by producing 2,3-diaminophenazine (oxOPD) under pH 8, which emits yellow fluorescence at 560 nm while quenching the blue fluorescence of N, Si, S-GQDs at 440 nm due to an inner filter effect. With the increase of Ag(I)/Fe(III), the blue fluorescence of N, Si, S-GQDs at 440 nm was gradually weakened, along with the enhancement of yellow fluorescence at 560 nm. Hence, this color change from blue to yellow under UV light enables semi-quantitative visual detection. The sensor demonstrates high sensitivity with detection limits of 0.016 µg mL-1 for Ag(I) and 0.010 µg mL-1 for Fe(III), and it successfully detects these ions in lake and tap water without pretreatment. The autocatalytic mechanism involves Ag(I) and Fe(III) reduction to Ag nanoparticles and Fe(II), respectively, which further catalyze the reaction, enhancing selectivity and efficiency. The method is cost-effective, simple, and suitable for on-site environmental monitoring.

Targeted bio-imaging in discriminating normal and cancerous cells using dual-doped carbon dots derived from Dahlia pinnata flower extract

This research delves into utilizing dual-doped (N & S) carbon dots (DDCDs) sourced from Dahlia pinnata flower extract for targeted bio-imaging, aiming to differentiate between normal and cancerous cells. The synthesized DDCDs, incorporating nitrogen and sulfur, exhibited unique optical, structural, and morphological properties with an average size of about 3.25 nm. These DDCDs demonstrate strong fluorescence and display excitation-dependent emission behavior, as confirmed by the results of photoluminescence spectroscopy. Folic acid conjugation with DDCDs enhances their specificity towards cancer cells expressing the folate receptor. Through comprehensive characterization, the study demonstrates the successful synthesis and functionalization of these DDCDs. Even at a concentration of 200 µg/ml, these DDCDs demonstrated low cytotoxicity. In vitro experiments on both normal and cancer cell lines reveal distinct fluorescence responses, showcasing the potential of these bio-compatible DDCDs for precise bio-imaging in cancer diagnostics. This work opens avenues for utilizing natural sources in nanomaterial synthesis for biomedical applications, contributing to the advancement of targeted cellular imaging technologies.

A cucurbit[6]uril-based carbon dot for recognizing metal ions and anions in solutions

In this paper, fluorescent nitrogen doped carbon quantum dots (CQDs) were synthesized by a hydrothermal method using cucurbit[6]uril (Q[6]) and mandelic acid (MA). Compared with other carbon quantum dots, cucurbit[6]uril has the advantage that its original rigid macrocyclic skeleton was completely retained during the synthesis process. In addition, the performance of the Q[6]-CQDs were characterized by fluorescence and NMR spectroscopies, then the crystal structure of Q[6]-MA-[CdCl4]2- was determined by the single crystal X-ray crystallography. The Q[6]-CQDs showed good water solubility and stable optical property. Subsequently, using the obtained Q[6]-CQDs, a universal fluorescent probe for detecting and recognizing Fe3+, Ba2+, Al3+, I- and ClO- has been developed based on macrocyclic chemistry. Under ideal conditions, the detection limits were calculated to be 3.89 × 10-6 M, 2.58 × 10-5 M, 1.42 × 10-5 M, 6.84 × 10-6 M and 1.50 × 10-5 M.

In situ microwave-assisted preparation of NS-codoped carbon dots stabilized silver nanoparticles as an off-on fluorescent probe for trace Hg2+ detection

An off-on fluorescent probe (NS-CDs-AgNPs) was synthesized based on a one-pot microwave process by utilizing N, S co-doping carbon dots (NS-CDs) and silver nitrate as precursors. The significant peak of NS-CDs-AgNPs at 393 nm in ultraviolet spectrum indicated silver nanoparticle (AgNPs) were successfully synthesized. A faint blue fluorescence emission (442 nm) was displayed when excited NS-CDs-AgNPs at 371 nm. A remarkable fluorescence recovery was observed upon adding of trance Hg2+, whereas the other heavy metal ions did not elicit this response. The reason for this phenomenon was revealed in this work that a spontaneous redox reaction occurred between NS-CDs-AgNPs and Hg2+, which leaded to the formation of NS-CDs-Agn-2NPsHg complexes. On the basis of this mechanism, a new off-on fluorescent analytical method was constructed for Hg2+ detection with linear range of 10-400 nM (R2 = 0.9941), and the detection limit (LOD) of 5.16 nM. Additionally, satisfactory recovery (90.28%-106.13%) and the relative standard deviation (RSD) (RSD＜5.21%) were obtained in water sample detection. More importantly, the NS-CDs-AgNPs exhibited lower cytotoxicity and better biocompatibility, indicating a huge potential in cell imaging and clinical medicine.

A Review on Interface Engineering of MXenes for Perovskite Solar Cells

With an excellent power conversion efficiency of 25.7%, closer to the Shockley-Queisser limit, perovskite solar cells (PSCs) have become a strong candidate for a next-generation energy harvester. However, the lack of stability and reliability in PSCs remained challenging for commercialization. Strategies, such as interfacial and structural engineering, have a more critical influence on enhanced performance. MXenes, two-dimensional materials, have emerged as promising materials in solar cell applications due to their metallic electrical conductivity, high carrier mobility, excellent optical transparency, wide tunable work function, and superior mechanical properties. Owing to different choices of transition elements and surface-terminating functional groups, MXenes possess the feature of tuning the work function, which is an essential metric for band energy alignment between the absorber layer and the charge transport layers for charge carrier extraction and collection in PSCs. Furthermore, adopting MXenes to their respective components helps reduce the interfacial recombination resistance and provides smooth charge transfer paths, leading to enhanced conductivity and operational stability of PSCs. This review paper aims to provide an overview of the applications of MXenes as components, classified according to their roles as additives (into the perovskite absorber layer, charge transport layers, and electrodes) and themselves alone or as interfacial layers, and their significant importance in PSCs in terms of device performance and stability. Lastly, we discuss the present research status and future directions toward its use in PSCs.

Numerical Simulation of Erosion Characteristics for Solid-Air Particles in Liquid Hydrogen Elbow Pipe

The crystalline solid-air in the liquid hydrogen will cause erosion or friction on the elbow, which is directly related to the safety of liquid hydrogen transportation. The CFD-DPM model was used to study the erosion characteristics of solid-air to liquid hydrogen pipelines. Results show that the outer wall of the cryogenic liquid hydrogen elbow has serious erosion in the range of 60–90°, which is different from the general elbow. The erosion rate is linearly positively correlated with the mass flow of solid-air particles, and the erosion rate has a power function relationship with the liquid hydrogen flow rate. The fitted relationship curve can be used to predict the characteristics and range of the elbow erosion. The structure of the liquid hydrogen elbow also has an important influence on the solid-cavity erosion characteristics. The increase of the radius of curvature is conducive to the reduction of the maximum erosion rate, while the average erosion rate undergoes a process of increasing and then decreasing. The radius of curvature is 60 mm, which is the inflection point of the average erosion rate of the 90° elbow. The research results are expected to provide a theoretical basis for the prevention of liquid hydrogen pipeline erosion.