Phosphorescence shows great potential for application in bioimaging and ion detection because of its long-lived luminescence and high signal-to-noise ratio, but establishing phosphorescence emission in aqueous environments remains a challenge. Herein, we present a general design strategy that effectively promotes phosphorescence by utilising water molecules to construct hydrogen-bonded networks between carbon dots (CDs) and cyanuric acid (CA). Interestingly, water molecules not only cause no phosphorescence quenching but also greatly enhance the phosphorescence emission. This enhancement behaviour can be explained by the fact that the highly ordered bound water on the CA particle surface can construct robust bridge-like hydrogen-bonded networks between the CDs and CA, which not only effectively rigidifies the C=O bonds of the CDs but also greatly enhances the rigidity of the entire system. In addition, the CD-CA suspension exhibits a high phosphorescence lifetime (687 ms) and is successfully applied in ion detection based on its visible phosphorescence.

No abstract

Borophene has been predicted to be a potential anode material of lithium-ion batteries because of its high specific capacity, high mechanical strength, and low diffusion barrier. However, borophene cannot be stable without metal substrates, impeding the industrial applications. Hence, using first-principles calculations, we proposed to form van der Waals heterostructures to improve the stability of monocomponent borophene and found graphene to be an alternative substrate for stabilizing borophene as a borophene/graphene (B/G) heterostructure. We find that B/G has a high adsorption energy of Li (−2.959 eV) and a high theoretical specific capacity (1469.35 mA h/g). Also, systematic climbing-image nudged elastic band calculations show that B/G has a low diffusion barrier (0.613 eV), and these properties change with the interlayer distance of B/G, theoretical specific capacity increasing to 1763.22 mA h/g, and diffusion barrier decreasing to 0.353 eV. Our results demonstrate that B/G is a promising anode material and that the electrochemical performance can be changed by adjusting the interlayer spacing.

The second near-infrared window emission (1.0-1.7 μm, NIR-II) has received extensive attention with the advantages of negligible tissue scattering, reduced autofluorescence, and less background noise. Here a novel analysis platform based on quantum dots (QDs) for highly selective detection of Zn and Cd with an enhanced NIR-II fluorescence is reported for the first time. We have developed a facile two-step route to synthesize the water-soluble AgS QDs, constituting of a green hydrothermal process and followed surface ligands exchange. Surface passivation was proposed to be the mechanism for the enhanced fluorescence. The added Zn or Cd could react with the surface thioglycollic acid to form Zn-thiol or Cd-thiol complex passivation shell, which restored surface defects and suppressed nonradiative recombination pathway. The detection platform exhibited a linear relationship between the ion concentrations and enhanced fluorescence and had a detection limit as low as 760 nM for Zn and 546 nM for Cd at pH = 7.4. Furthermore, the as-synthesized AgS QDs showed good robustness in real sample matrix and were demonstrated to be able to detect exogenous Zn(II) in cells. These properties suggest potential applications of detection of Zn in biology and Cd in environment via the NIR-II fluorescent AgS QDs.

Once two-dimensional boron-based materials were forecasted, their excellent physical and chemical properties have realized attractive application value in the field of materials science. However, borophene could not exist independently and stably in nature. Molecular beam epitaxy is the only way being used currently for the preparation of borophene, which has low yield and harsh experimental installation conditions. Here, we propose the theory that few-layer borophene supported by silver nanoparticles can exist stably and large-scale preparation of few-layer borophene can be performed by mechanical resonance first. We have revealed that the structure of the prepared borophene is α-sheet and its thickness is less than 4 nm. The oxidation rate of borophene from the experiment is about 0.19, which indicates that the few-layer borophene possesses good structure stability. We have also studied the structure stability of borophene on silver nanoparticles by first principles calculation. The calculation proves that few-layer borophene can exist stably supported with silver nanoparticles. Furthermore, the terahertz shielding and stealth performance of the few-layer borophene have been explored. The maximum terahertz shielding effectiveness value of the prepared material could reach up to 50 and 21.5 dB for the reflection loss value in the broadband range of 0.1–2.7 THz. The large-scale preparation of few-layer borophene through the mechanical method makes it possible to study the properties of borophene and achieve low-cost large-scale applications, such as the study of terahertz shielding and stealth performance in the article, which facilitates the lightweight material design for terahertz shielding and stealth.