Herein, we report an eco-friendly and simple fluorescent nitrogen-doped carbon quantum dot (N-CQD) biosensor which was synthesized via a hydrothermal method using erhanediamine (EDA) and citric acid (CA) as precursors. The surface functionalization of N-CQDs exhibited a bright blue emission under the excitation wavelength of 350 nm. The obtained N-CQDs were characterized by atomic force microscopy (AFM), Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, and transmission electron microscopy. It was found that the surface of the CQDs was successfully functionalized. After that, as-prepared N-CQDs were further applied in Fe(III) detection. Spectroscopic data indicated that fluorescent carbon-based nanomaterials displayed a sensitive response to Fe ³⁺ in the range of 0.5–1000 μ M as a fluorescence sensor in real environmental samples. Furthermore, the results also showed that a novel N-CQD nanomaterial could be employed as an ideal fluorescent Fe(III) probe.

Flexible solid-state zinc–air batteries as a wearable energy storage device with great potential, and their separators, which control ion permeability, inhibit zinc dendrite generation, and regulate catalytic active sites, have been developed as gel electrolyte separators with high retention of electrolyte uptake. However, the gel electrolyte separator still has problems such as poor affinity with the electrolyte and poor ionic conductivity, which limits its further application. In order to further improve the electrolyte absorption, ionic conductivity and mechanical strength of cellulose acetate(CA)/polyvinyl alcohol (PVA) nanofibers, TiO₂ was added to CA/PVA to increase the porosity, and glutaraldehyde (GA) was used to modify the CA/PVA/TiO₂ separator by acetal reaction with CA and PVA to make the molecules closely linked. The results shows that the optimal mass fractions of TiO₂ and GA were 2% and 5%, respectively. At this time, the porosity and absorption rate of the separator increased from 48% to 68.2% and 142.4% to 285.3%, respectively. The discharge capacity reached 179 mA cm⁻³, and the cycle stability rate was 89% after 7 stable constant current charge/discharge cycles.