Zheng Liu

NASICON-type Na3V2(PO4)3 (NVP) is considered a promising cathode material for aqueous zinc-ion batteries due to its high operating voltage and substantial specific capacity. However, its practical application is significantly limited by poor electronic conductivity. To solve this problem, this paper introduces a carbon sphere framework supporting carbon-coated NVP (denoted as NVP-C@CSs). This composite was synthesized via a combination of hydrothermal and high-temperature calcination methods, which simultaneously improve conductivity and zinc storage capacity. The results indicate that the crystal structure of NVP remains intact after the introduction of CSs. Benefiting from the conductive CS framework, the NVP-C@CSs composite exhibits enhanced electronic conductivity (1.60 × 10⁻⁴ vs. 1.20 × 10⁻⁴ S cm⁻¹) and consequently superior electrochemical performance. At a low current density of 100 mA g⁻¹, the NVP-C@CSs composite delivers a discharge specific capacity of 126 mAh g⁻¹, higher than that of the NVP-C material (113 mAh g⁻¹). The composite also exhibits excellent rate capability, with a capacity of 90 mAh g⁻¹ at 2000 mA g⁻¹, significantly exceeding that of NVP-C (59 mAh g⁻¹). This work provides an efficient approach to developing high-performance NVP composites for zinc-ion batteries.

Dual-response-reverse ratiometric fluorescence paper sensor based on G-BCQDs/Zr-MOFs for biogenic amine (spermine) detection via smartphone RGB analysis.

The pervasive concern regarding veterinary drug residues in food necessitates advanced detection solutions, particularly addressing limitations of conventional methods reliant on large-scale instrumentation that incur prolonged analysis duration, complex sample preparation, and lack of real-time on-site capability. A portable “single response-on” molecularly imprinted ratiometric fluorescent paper-based sensor was developed for quantifying fleroxacin (FLX) residues in animal-derived foods, wherein B, N-co-doped MXene quantum dot (B, N-MQD) was synthesized and combined with BCP-Eu as dual-emission fluorophores, while FLX- molecularly imprinted polymer (FLX-MIP) was engineered using functionalized Nano-SiO₂ as the carrier. Concentration-dependent fluorescence enhancement at 574 nm was exhibited with invariant reference signal at 411 nm, achieving a 36-fold lower detection limit (0.49 µM) versus the non-imprinted probe (17.78 µM) and linear response across 25.0 ~ 200.0 µM. When integrated with smartphone visualization, 25.0 ~ 350.0 µM linearity, 4.78 µM detection limit, and 89.80 ~ 96.44% recoveries were demonstrated in real samples, validating reliability for on-site screening. * Corresponding authors. E-mail: lisa4.6@163.com(Z. Liu), peter.zou@rid-lab.cn(P.T. Zou), hangc81@guet.edu.cn(G.-C. Han).

A visual detection method for malachite green (MG) in food was established based on ‘double-response-OFF’ ratiometric fluorescent paper-based sensor. Biomass carbon quantum dots (BCQDs) using broad bean shell, and Ti₃C₂MXene quantum (MQDs) dots modified by ethylenediamine were synthesized by solvothermal method. The MG and two kinds of quantum dots could undergo static quenching, and the fluorescence color of two kinds of quantum dots gradually changed from red to blue, eventually the fluorescence was quenched, and the pattern had a two-stage linear relationship using fluorescent spectrofluorometer in the range of 0.1–140.0 μM and the detection limit of 0.07 μM. On this basis, a BCQDs/MQDs ratiometric fluorescence paper-based sensor was constructed and applied to fish sample. Through mobile phone software-Color recognizer, RGB values of fluorescent paper-based sensor at various concentrations of MG were extracted. The results showed that MG concentration was linearly correlated with R’ value of RGB in the range of 20.0–140.0 μM with 16.5 μM detection limit. The method had been applied to the determination of canned fish and fresh basa fish samples, and the recovery rates were 97.33%–108.93% and 96.04%–117.97%, respectively. It proved that the ratiometric fluorescent paper-based sensor could be used for the rapid visual quantitative detecting MG in real samples.

Pesticide residues are a serious problem towards agriculture, environment and food safety, so it is highly desirable to develop a swift, efficient and portable pesticide detection method. A fluorescence visual sensing method for glyphosine based on a nitrogen-doped biomass carbon quantum dot (N-CQD) paper-based sensor was developed. The fluorescence signal was quenched by Fe³⁺ in a static quenching process, and then the fluorescence of N-CQDs was recovered after adding glyphosine. Under the optimal experimental conditions and when tested with a fluorescence spectrofluorometer, the detection of glyphosine showed a two-stage linear pattern in the range of 0.1–0.6 μM and 0.6–1.6 μM with a detection limit of 0.075 μM. Then, the RGB values of different concentrations of glyphosine on the filter paper chip were detected by the software of the smartphone-color identifier. The logarithm of the glyphosine concentration was linearly related to the G value of RGB in the range of 0.25–10.00 mM and with a detection limit of 0.15 mM. The method was applied to measuring glyphosine-spiked juice and flour samples, and the recovery rates were 87.60–112.69% and 93.27–105.83%, respectively. The proposed N-CQDs/Fe³⁺ system had wide applications, and it was expected to be fast and effective at detecting pesticide residues.

The 3,4-ethylenedioxyethiophene-2,5-dicarboxylic acid (H₂L₁) and 4-chloropyridine-2, 6-dicarboxylic acid (H₂L₂) were used as the main ligands and 4,4' -bipyridine (L₃) as the auxiliary ligand and the complexes {[Ni(L₁)₂(L₃)(H₂O)]·[(DMF)₂(H₂O)]}n(I), {[Cu(L₂)(L₃)H₂O]·H₂O}(II) were synthesized by solvent thermal reaction. The structure and properties of the complexes were characterized by X-ray single crystal diffraction, infrared spectroscopy (IR), fluorescence spectrum and thermogravimetric analysis. The results showed that complex I is a three-dimensional network structure. Complex II is formed with Cu(II) ions as the metal nodes and ligands as connecters, and a one-dimensional chain structure is further formed by intermolecular hydrogen bonding interaction.