RSC Advances Blog

Graphene-wrapped nanosilicon for high performance Li-ion batteries

Chinese scientists have used graphene sheets to wrap silicon nanoparticles to make nanocomposites which resemble bath lilies.

Zi-Feng Ma and co-workers, from Shanghai Jiao Tong University, have assessed the performance of the novel bath lily-like graphene sheet-wrapped silicon (GS-Si) nanocomposites as anode materials for Li-ion batteries. They showed that the GS-Si nanocomposites exhibit a high reversible capacity of 1525mAh g^–1 and superior cycling stability.  Conventional graphite anodes display a theoretical specific capacity of only 372 mAh g^-1, making it a weak candidate for anodes of Li-ion batteries.

The GS-Si nanocomposites were synthesised using a spray-drying technique which requires “no surfactant, no filtration or washing processes and no high vacuum conditions.” The authors believe that the procedure is safe and environmentally friendly and can be scaled up for the mass production of graphene-based composite materials.

The obtained GS-Si composite possesses an open nano/micro-structure, in which nanosized Si particles are uniformly dispersed and wrapped in the graphene sheet (GS) matrix. “The GS not only constitutes a good conducting network, but also provides enough void spaces to accommodate the volume change of Si and prevent the aggregation of nano-Si particles during cycling, ” explains Ma et al.

Find out more about graphene sheet-wrapped nanocomposites by downloading the full article for free until December 2012.

A novel bath lily-like graphene sheet-wrapped nano-Si composite as a high performance anode material for Li-ion batteries
Yu-Shi He, Pengfei Gao, Jun Chen, Xiaowei Yang, Xiao-Zhen Liao, Jun Yang and Zi-Feng Ma
RSC Adv., 2011, 1, 958-960

A self-healing polymer coating that changes from clear to red when damaged has been developed by a research team in the US. The coating repairs itself in sunlight, under heating or with exposure to acidic vapours, and becomes clear again.

Marek Urban, leading researcher at the University of Southern Mississippi, explains that the polymer “films are capable of sensing color changes upon mechanical scratches, but upon exposure to the visible (VIS) portion of the electromagnetic radiation (y580 nm), temperature, and/or acidic atmospheres, not only mechanical damage is repaired, but also the mechanically induced red coloured scar vanishes.”

The red colour is because of a ring-opening reaction to form merocyanine, which is red. As the ring closes again under light, heat or an acidic vapour, it forms spironaphthoxazine, which is clear.

Want to find out more? Download the full paper for free until December 2012.

Self-repairable copolymers that change color
Dhanya Ramachandran, Fang Liu and Marek W. Urban
RSC Adv., 2012, Advance Article, DOI: 10.1039/C1RA00137J

Carbon nanotubes that look like cups stacked on top of each other have been functionalized with cellulase enzyme to enable them to penetrate inside cells through induced nanoholes without damaging the entire plant cell wall.

Plant cell wall is a unique barrier made up of cellulosic materials which prevent the passage of macromolecules inside the cells. Traditionally, when studying plant biology, scientists strip away the cell wall using cellulase (an enzyme that causes cellulose hydrolysis) or other chemical treatments. The latter procedures to disorganize the cell walls may affect the cell viability or the cell’s capability to divide.

Scientists at Nagoya University in Japan, have developed a clever way to functionalize cup-stacked carbon nanotubes functionalized on their tips and walls with cellulase. The immobilized cellulase is proposed to induce local lesions in the cell wall, through which carbon nanotubes can transport into the interior of the cell.

The authors believe that this new method could open a lot of opportunities for studying plant cell genetics or plant diseases.

Download the full article for free by simply registering here.

Introducing carbon nanotubes into living walled plant cells through cellulase-induced nanoholes
Maged F. Serag, Noritada Kaji, Manabu Tokeshi and Yoshinobu Baba
RSC Adv., 2012, Advance Article, DOI: 10.1039/C1RA00760B, Communication