Chang Liu

The Preparation of Graphene Reinforced Poly(vinyl alcohol) Antibacterial Nanocomposite Thin Film

Methylated melamine grafted polyvinyl benzylchloride (mm-g-PvBCl) was prepared which was used as additive in poly(vinyl alcohol) (PVA) and graphene nanosheets (GNs) were used to reinforce the mechanical strength. Using casting method, antimicrobial nanocomposite films were prepared with the polymeric biocide loading lever of 1 wt%, 5 wt%, and 10 wt%. Thermogravimetric analysis (TGA) characterization revealed the 2.0 wt% of graphene content in resultant nanocomposites films. XRD showed that the resultant GNs 2 theta was changed from 16.6 degree to 23.3 degree. Using Japanese Industry Standard test methods, the antimicrobial efficiency for the loading lever of 1 wt%, 5 wt%, and 10 wt% was 92.0%, 95.8%, and 97.1%, respectively, against gram negative bacteria E. coli and 92.3%, 99.6%, and 99.7%, respectively, against the gram positive S. aureus. These results indicate the prepared nanocomposite films are the promising materials for the food and drink package applications.

In-Situ Template Formation Strategy for the Preparation of Nitrogen Doped Carbon Nanocage with Graphitic Shell as Electrode Material for Supercapacitor

Nitrogen doped carbon nanocage with graphitic shell (NGCS) was fabricated through in-situ solid reaction between calcium acetate and dicyandiamide in an inert atmosphere followed by acid etching. The role played by the calcium acetate (Ca(Ac)2) and dicyandiamide (DCD) during the synthesis process is one-stone-two-birds. Calcium acetate plays multiple functions: template agent, graphitization catalyst, and carbon source. Dicyandiamide can be considered as the nitrogen sources and the chemical reaction agent that can be reacted with calcium acetate to form it into CaCN2. The NGCS obtained at 800 °C has a specific surface area of 420 m2/g and nitrogen content of 8.87 at%. The excellent electrochemical performance can be attributed to the combination effects of porous structure, nitrogen doping and graphitized nanocage shell of NGCS electrode. The hollow structure serves as the reservoir for fast electrolyte ion supplement. Nitrogen groups not only improve the wettability of interfaces between carbon surface and electrolyte, but also generate extra pseudocapacitance through redox reaction. The graphitic carbon nanocage shell can enhance the conductivity and facilitates the fast charge transfer. At a current density of 0.5 A/g, the specific capacitance of the NGCS-800 electrode is 215 F/g. Furthermore, the NGCS-800 electrode exhibits excellent rate capability (80% capacitance retention at 10 A/g) and outstanding cycling stability (96.89% capacitance retention after 5000 cycles). These intriguing results demonstrate that nitrogen doped carbon with graphitic shell will be highly promising as electrode materials for supercapacitors and other energy storage and conversation applications.