Nanohybrids that consisit of p-type, nitrogen-doped ZnO and graphene nanostructures: synthesis, photophysical properties, and biosensing application.

ZnO, a promising material for optoelectronic applications, has attracted considerable attention due to its wide and direct band gap and large exciton binding energy. To understand the applications of this material, fabrication of high quality p-type ZnO is a key step. However, a reliable p-type doping of this material remains a major challenge. In this study, we report p-type nitrogen-doped ZnO nanoparticle, grown in a nitrogen doped graphene layer matrix by a plasma heating process using a natural protein and zinc nitrate as the precursors. The structural characterizations are developed by several microscopic techniques including the field emission electron microscopy, high resolution transmission electron microscopy, x-ray photoelectron spectroscopy, and micro-Raman analysis. In addition, the ultraviolet (UV)-visible absorption characteristics and photoluminescence properties of the samples are studied. Its p-type conduction behaviour is confirmed by the Hall effect measurement, which was ascribed to the high nitrogen dopant concentration in the Zn-poor ZnO, and the related mechanism for the p-type behaviour is also discussed. Moreover, the results of the glucose detection based on the strong green luminescence of glucose indicate that the nitrogen-doped ZnO nanodots/nitrogen-doped graphene layer nanohybrid is also a competitive candidate in the biosensing field.

Ultra-highly fluorescent N doped carbon dots-CdTe QDs nanohybrids with excitation-independent emission in the blue-violet region.

Luminescent carbon dots (CDs) are of significant practical application interest such as in optoelectronic devices and sensitive probing in the life science and environment fields. In this study, N doped CDs-CdTe quantum dots (QDs) nanohybrids (CdTe/N-CDs) were synthesized by a plasma heating process using silk fibroin and CdTe QDs as precursors. The synthesis, doping, hybridizing and passivation of the CdTe/N-CDs were carried out in a single-step process. The as-synthesized CdTe/N-CDs dispersed in ethanol exhibited blue-violet photoluminescence with excitation-independent emission characteristics (strong emissions at 405 nm and 429 nm, and a weak emission at 456 nm). Additionally, the optimal excitation wavelength for the CdTe/N-CDs was found at 360-380 nm, which very closely matches the intrinsic wavelength of GaN-based LEDs. Furthermore, the obtained CdTe/N-CDs exhibited a very high quantum yield of ∼84%, showing great potential in developing chip-based high performance optoelectronics devices. The emission mechanism and emission enhancement by related factors including N-bonded configurations in the carbon base and the transfer of photo-excited electrons from the CdTe QDs to the N doped CDs were studied, as well.

N-doped graphene-based copper nanocomposite with ultralow electrical resistivity and high thermal conductivity.

Nanocomposite with a room-temperature ultra-low resistivity far below that of conventional metals like copper is considered as the next generation conductor. However, many technical and scientific problems are encountered in the fabrication of such nanocomposite materials at present. Here, we report the rapid and efficient fabrication and characterization of a novel nitrogen-doped graphene-copper nanocomposite. Silk fibroin was used as a precursor and placed on a copper substrate, followed by the microwave plasma treatment. This resulted nitrogen-doped graphene-copper composite possesses an electrical resistivity of 0.16 µΩ·cm at room temperature, far lower than that of copper. In addition, the composite has superior thermal conductivity (538 W/m·K at 25 °C) which is 138% of copper. The combination of excellent thermal conductivity and ultra-low electrical resistivity opens up potentials in next-generation conductors.