Carbon dots (CDs) can be widely used in the field of sensing because of its good water solubility, low toxicity, high fluorescence stability and excellent biocompatibility. It has become a popular trend to prepare high-value, inexpensive, renewable and environmentally friendly CDs sensors from biomass resources. This article reviewed the research progress of biomass-derived CDs as chemical, physical and biological sensors in recent years and studied their preparation processes and sensing abilities. Furthermore, the prospects and challenges of biomass-CDs sensors were discussed. This article is expected to provide inspirations for the design, preparation and application of biomass-CDs sensors in the future.

The addition of abundant fillers to obtain conductive and superhydrophobic waterborne polyurethane (WPU) composites generally results in increased interfaces in the composites, leading to reduced adhesion and poor corrosion resistance. Fillers such as Polytetrafluoroethylene (PTFE) and multi-walled carbon nanotubes (MWCNTs) were first treated by a coupling agent to reduce the contents of the fillers. Thus, in this work, WPU superhydrophobic conductive composites were prepared using electrostatic spraying (EsS). The polar groups (-OH and -COOH, etc.) on the WPU, PTFE, and MWCNTs were reacted with the coupling agent, making the WPU, PTFE, and MWCNTs become crosslinked together. Thus, the uniformity of the coating was improved and its curing interfaces were reduced, causing enhanced corrosion resistance. The dehydration reaction that occurred between the silane coupling agent and the polar surface of Fe formed -NH₂ groups, increasing the adhesion of the coating to the steel substrate and then solving the problems of low adhesion, easy delamination, and exfoliation. With the increased content of the modified fillers, the conductivity and hydrophobic property of the composite were amplified, and its corrosion resistance and adhesion were first strengthened and then declined. The composite with the WPU, PTFE, MWCNTs, and KH-550 at a mass ratio of 7:1.5:0.1:0.032 held excellent properties; its volume resistivity and WCA were 1.5 × 10⁴ Ω·cm and 155°, respectively. Compared with the pure WPU coating, its adhesive and anticorrosive properties were both better. This provides a foundation for the fabrication and application of anticorrosive and conductive waterborne composites.

In this article, nitrogen-doped carbon dots (N-CDs) were prepared by a hydrothermal method using microcrystalline cellulose as the carbon source and polyethylenimine as the nitrogen source. The ratio of microcrystalline cellulose to polyethylenimine added exerted a great influence on the fluorescence quantum yield of N-CDs. The fluorescence intensity of N-CDs 2 was significantly affected by the solvent type and pH value, but not influenced by the time of irradiation with the UV lamp. Intriguingly, N-CDs 2 could be applied to temperature sensing (30~70 °C). With the addition of Fe³⁺ (20 ppm), the fluorescence of N-CDs 2 was greatly quenched, and the quenching rate reached 82.84%. The fluorescence intensity of N-CDs 2 showed a good linear relationship (R² = 0.995) with Fe³⁺ concentrations (0~14 ppm), and they achieved a limit of detection of 0.21 ppm. In addition, N-CDs 2 could also effectively detect Fe³⁺ in real water samples, showing a good recovery rate (98.25%~102.75%) and low relative standard deviation (less than 3%). According to the fluorescence lifetime data, the fluorescence quenching of N-CDs by Fe³⁺ might be a static process.