Special substrates enable large single crystal bi-/tri-layer graphene growth

Researchers of the Center for Multidimensional Carbon Materials (CMCM) within the Institute for Basic Science (IBS, South Korea), in collaboration with UNIST and Sungkyunkwan University teams, have reported the fabrication and use of single crystal copper-nickel alloy foil substrates for the growth of large-area, single crystal bilayer and trilayer graphene films.

The growth of large area graphene films with a precisely controlled number of layers and stacking order can open new possibilities in electronics and photonics but remains a challenge. This study showed an example of the synthesis of bi- and trilayer graphene sheets larger than a centimeter, with layers piled up in a specific manner, namely AB- and ABA-stacking.

New method uses hydrogen plasma to smooth out wrinkles in graphene

Researchers from Nanjing University in China have developed a method to make large graphene films free of any wrinkles. The ultra-smooth films could enable large-scale production of electronic devices that harness the unique physical and chemical properties of graphene and other 2D materials.

Wrinkles  disappear when graphene is treated with a hydrogen plasma imageWrinkles in graphene films grown via chemical vapor deposition appear as jagged white lines at the top of this atomic force microscope image (left), but they disappear when the material is treated with a hydrogen plasma (right). Credit: Nature

Chemical vapor deposition (CVD) is the best-known method for making high-quality graphene sheets. It typically involves growing graphene by pumping methane gas onto copper substrates heated to temperatures around 1,000 °C, and then transferring the graphene to another surface such as silicon. But some of the graphene sticks to the copper surface, and as the graphene and copper expand and contract at different rates, wrinkles form in the graphene sheets. Such wrinkles often present hurdles for charge carriers and lower the film’s conductivity. Other researchers have tried to reduce wrinkles using low growth temperatures or special copper substrates, but the wrinkles have proven difficult to eliminate entirely, according to Libo Gao, a physicist at Nanjing University.

Log9 Materials bets on graphene-based aluminium fuel cells for future EVs

India-based Log9 Materials, believes that the key to better EVs is to focus on energy-generation, instead of energy storage. Log9 Materials says that a car powered by aluminium fuel cells can have a range of 1000 km post which the aluminium plates can be replaced within minutes.

According to Log9, aluminium fuel cells would primarily use three components – aluminium, water, and carbon in the form of graphene. In simple words, there’s water between layers of graphene, and when aluminium comes in contact with water, it corrodes – releasing energy. Log9 explains that procuring raw materials for aluminium fuel cells is much simpler than those for lithium-ion batteries which use lithium and cobalt, so manufacturing cost can be considerably lower for aluminium fuel cells than lithium-ion battery packs.

New graphene-based lithium-air battery may enable longer-running electric cars

Researchers at the Korean Daegu Gyeongbuk Institute of Science and Technology (DGIST) have fabricated an electrode using nickel cobalt sulphide nanoflakes on a sulfur-doped graphene, leading to a long-life battery with high discharge capacity. This improvement of lithium-air batteries' performance may bring us a step closer to electric cars that can use oxygen to run longer before they need to recharge.

"The driving distance of electric cars running on lithium-ion batteries is about 300 kilometers," says chemist Sangaraju Shanmugam of DGIST. "This means it's difficult to make a round trip between Seoul and Busan on these batteries. This has led to research on lithium-air batteries, due to their ability so store more energy and thus provide longer mileage."

Graphene exhibits strange ‘melting’ behavior

Physicists from the Moscow Institute of Physics and Technology and the Institute for High Pressure Physics of the Russian Academy of Sciences have set out to refine the melting curve of graphite using computer modeling, and made interesting observations on graphene's melting properties.

The team'a results show that the liquid carbon structure undergoes changes above the melting curve of graphene. The researchers explain that no graphene melting experiments have been conducted. Previously, computer models predicted the melting point of graphene at 4,500 or 4,900 K. Two-dimensional carbon was therefore considered to have the highest melting point in the world.