SnSe 2 is an anisotropic binary-layered material with rich physics, which could see it used for a variety of potential applications. Here, we investigate the gas-sensing properties of SnSe 2 using first-principles calculations and verify predictions using a gas sensor made of few-layer SnSe 2 grown by chemical vapor deposition. Theoretical simulations indicate that electrons transfer from SnSe 2 to NO 2 , whereas the direction of charge transfer is the opposite for NH 3 . Notably, a flat molecular band appears around the Fermi energy after NO 2 adsorption and the induced molecular band is close to the conduction band minimum. Moreover, compared with NH 3 , NO 2 molecules adsorbed on SnSe 2 have a lower adsorption energy and a higher charge transfer value. The dynamicsensing responses of SnSe 2 sensors confirm the theoretical predictions. The good match between the theoretical prediction and experimental demonstration suggests that the underlying sensing mechanism is related to the charge transfer and induced flat band. Our results provide a guideline for designing high-performance gas sensors based on SnSe 2 . KEYWORDS: SnSe 2 , gas sensing, charge transfer, first-principles calculations, selective gas sensing, NO 2 gas sensor, NH 3 gas sensor

Graphene is a single layer of carbon atoms with a large surface-to-volume ratio, providing a large capacity gas molecule adsorption and a strong surface sensitivity. Chemical vapor deposition-grown graphene-based NO 2 gas sensors typically have detection limits from 100 parts per billion (ppb) to a few parts per million (ppm), with response times over 1000 s. Numerous methods have been proposed to enhance the NO 2 sensing ability of graphenes. Among them, surface decoration with metal particles and metal-oxide particles has demonstrated the potential to enhance the gas-sensing properties. Here, we show that the NO 2 sensing of graphene can be also enhanced via decoration with monodisperse polymer beads. In dark conditions, the detection limit is improved from 1000 to 45 ppb after the application of polystyrene (PS) beads. With laser illumination, a detection limit of 0.5 ppb is determined. The enhanced gas sensing is due to surface plasmon polaritons excited by interference and charge transfer between the PS beads. This method opens an interesting route for the application of graphene in gas sensing.

Today cancer is one of the most life-threatening diseases in the world. The conventional cancer therapies, including surgery, chemo- and radiation therapies, have some disadvantages, such as limited efficiency and significant side effects. It is necessary to develop new therapeutic treatments. Herein, we integrated the targeted photocatalytic and chemotherapy in a multifunctional drug-delivery platform. The aptamer-functionalized ZnO nanoparticles (NPs) were successfully synthesized. The anti-cancer drug was loaded in the aptamer-ZnO NP system. In vitro cell cytotoxicity experiments showed that combined therapy had a higher rate of death of cancer cells compared to that of single photocatalytic or chemotherapy. Furthermore, aptamer-functionalization could greatly increase the accumulation of nanoparticles within cancer cells and lead to better therapeutic effects. The results suggest that aptamer-functionalized semiconductor nanoparticles may have potential in the development of targeted photocatalytic and chemotherapy against cancer.

We report on synthesis of nanoscale graphene oxide (NGO) by modified Hummers'method. Synthesized NGO particles were surface functionalized by attaching carboxylic acid and polyethylene glycol groups to render them soluble in cell culture medium. The structures and properties of functionalized NGO were characterized by transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and zeta potential analyzer. Cell viability studies show that PEG-modified NGO particles are highly soluble and incur almost no cytotoxicity to A549 cells, which suggest a great potential for the use of NGO in various biomedical applications.

The photoelectrical properties of graphene integrated with doped GeSn have been investigated and a high performance broadband photodetection can be achieved by integration of graphene with n-type GeSn.