N-doped carbon dots as the multifunctional fluorescent probe for mercury ion, glutathione and pH detection.

Recently, carbon dots (CDs) have exhibited promising applications in the fluorescence detection of various ions and biomolecules. In this work, one kind of nitrogen-doped CDs (N-CDs) with high fluorescence intensity was synthesized, characterized by transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, Fourier-transform infrared, UV-vis absorption spectra, and fluorescence spectra. The results show that the spherical and uniform N-CDs (quantum yield: 60.2%) have remarkable fluorescence properties and photostability, which makes N-CDs can be utilized as an 'on-off-on' sensor for Hg2+and glutathione (GSH). In addition, the pH-sensitive behavior of N-CDs makes it also applicable to H+detection under acid conditions (pKa = 3.53). The linear range of the 'turn-off' sensor detecting Hg2+was 0.014-50µM, with a 0.014µM limit of detection (LOD). GSH was detected by the fluorescence 'turn-on' method with a linear range of 0.125-60µM and a LOD of 0.125µM. The outstanding performance of N-CDs makes it potential applications in ecological pollution and biomolecule visualization monitoring.

The on-off-on Fluorescence Sensor of Hollow Carbon Dots for Detecting Hg2+ and Ascorbic Acid.

Carbon dots (CDs) have excellent fluorescence properties and can be used in many research fields. In this paper, carbon dots were prepared by microwave-assisted pyrolysis of citric acid and urea, characterized by transmission electron microscope (TEM), X-ray diffractometer (XRD), 13C-NMR spectrum, zeta potential, Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible (UV-vis) absorption and fluorescence spectra, and detected the Hg2+ and ascorbic acid (AA) sequentially. It showed that carbon dots were hollow, spherical particles and less than 10 nm, photoluminescence quantum yield of carbon dots was about 15%. The CDs were selective and sensitive to Hg2+ and AA based on the "on-off-on" fluorescence behavior. The detection limits of CDs for Hg2+ and AA were 0.138 µM and 0.212 µM, respectively. Fluorescence response mechanism of CDs was also discussed.

Financial technology, industrial ecology and energy efficiency.

To achieve peak carbon neutrality, it is necessary to transform energy structures, promote industrial ecology, and enhance energy efficiency. Employing provincial panel data from 2011-2020, we empirically investigate the impact of financial technology on energy efficiency and the role of industrial ecology in the development of financial technology to enhance energy efficiency. The findings reveal that financial technology can significantly enhance energy efficiency and promote it by improving industrial ecology. Furthermore, industrial ecology can act as a crucial channel for financial technology to promote energy efficiency. Specifically, an increase of one standard deviation in financial technology is associated with a 33.1% surge in energy efficiency on average. Financial technology has made a significant contribution to the improvement of energy efficiency in all regions, albeit with regional heterogeneity. Under different threshold variables, financial technology exerts a facilitating effect on the enhancement of energy efficiency; the impact of financial technology on energy efficiency remains heterogeneous.