Reduced graphene oxide: an introduction - Page 3

This is a sponsored article by Dr Richard Collins, IDTechEx

Graphene is on the cusp of significant market growth; the opportunities are exciting and diverse, each with significant potential. Graphene and 2D Materials Europe 2020 (13-14 May, Berlin) is the largest B2B event on the topic with a dedicated focus on the commercial frontiers. www.GrapheneEurope.tech

There is often confusion surrounding the types of graphene, commercial status, and their target markets. This article will briefly summarise each and showcase what to expect at this event.

The US Department of Energy’s (DOE) Office of Fossil Energy (FE) has selected three projects to receive approximately USD$3 million in federal funding for cost-shared research and development projects.

Among these projects is a laboratory-scale coal-derived graphene process the University of North Dakota will demonstrate a laboratory-scale coal-derived graphene process to produce graphene oxide, reduced graphene oxide, and graphene quantum dots starting from domestic US coal.

A new study by Brown University shows that graphene sheets can block the signals mosquitoes use to identify a potential blood 'donor', which may enable a new chemical-free approach to mosquito bite prevention.

The researchers showed that multilayer graphene can provide a two-fold defense against mosquito bites. The ultra-thin yet strong material acts as a barrier that mosquitoes are unable to bite through. At the same time, experiments showed that graphene also blocks chemical signals mosquitoes use to sense that a blood meal is near, blunting their urge to bite in the first place. The findings suggest that clothing with a graphene lining could be an effective mosquito barrier, the researchers say.

A team of researchers from China has reported a novel strategy to 'stitch' together reduced graphene oxide (rGO) nanosheets into ultra-strong, tough, and highly conductive graphene films using only small amounts of cross-linker. They show that the bridging of long-chain π-π bonding agent between neighboring rGO nanosheets can provide substantial improvement in multiple properties including tensile strength, toughness, electrical conductivity, EMI shielding capability, and resistance to mechanical damage.

"Our graphene films not only demonstrate a record tensile strength of almost 1.1 GPa, but exceptional abilities to absorb mechanical energy, transport charge, and shield electromagnetic interference that are comparable to or even superior to graphene films annealed at much higher temperatures," says Qunfeng Cheng, a professor at Beihang University in Beijing. "Our process uses abundant natural graphite as a raw material at room temperature. This novel strategy can provide an inspiration for converting low-priced graphite powders into much higher performance macroscopic graphene films for diverse commercial uses in the future."

Global Graphene Group, and its subsidiary Angstron Energy (AEC) has developed a new graphene/silicon composite anode material (GCA-II-N) which can increase the capacity of Li-Ion batteries while reducing the battery's size and weight. AEC current market focus is on electronic bikes and consumer electronics, but is also working with Tier-1 electric cars and trucks makers.

AEC tells us that by wrapping single-layer graphene (or r-GO) around silicon nanoparticles, the volume expansion/contraction of the Silicon during the battery's charge/discharge cycle can be cushioned by the flexibility and mechanical strength of the graphene. The graphene sheets also form a 3D conductive network which ensures good electrical contacts between the Silicon particles and the current collector.

Researchers at Chalmers University of Technology, Sweden, have recently developed a promising breakthrough for lithium sulphur batteries, using a catholyte with a graphene sponge. Such batteries may offer a theoretical energy density more than five times that of lithium ion batteries.

Structure of the lithium sulfur battery

The researchers' approach relies on a porous, sponge-like aerogel, made of reduced graphene oxide, that acts as a free-standing electrode in the battery cell and allows for better and higher utilization of sulphur.

Researchers from the Graphene Flagship have developed hybrids of graphene and molybdenum disulphide quantum dots to stabilize perovskite solar cells (PSCs). PSCs are a novel type of solar cells which are efficient, relatively easy to produce, made with cheaper materials and, due to their flexibility, can be used in locations where traditional silicon solar cells cannot be placed.

A collaboration between the Graphene Flagship Partners Istituto Italiano di Technologia, University of Rome Tor Vergata, and BeDimensional resulted in a novel approach based on graphene and related materials to stabilize PSCs, thus addressing the stability issue of PSCs, a major hurdle hindering their commercialization.

Researchers at Swinburne, the University of Sydney and Australian National University have collaborated to develop a solar absorbing, ultra-thin graphene-based film with unique properties that has great potential for use in solar thermal energy harvesting.

The 90 nanometre material is said to be a 1000 times finer than a human hair and is able to rapidly heat up to 160°C under natural sunlight in an open environment.

Researchers from Washington University have designed a novel membrane technology that purifies water while preventing biofouling, or buildup of bacteria and other harmful microorganisms that reduce the flow of water. And they used graphene and bacteria to build these filtering membranes.

The team developed an ultrafiltration membrane using graphene oxide and bacterial nanocellulose that they found to be highly efficient, long-lasting and environmentally friendly. If their technique were to be scaled up to a large size, it could benefit many developing countries where clean water is scarce.

Today we published a new article, an introduction to reduced graphene oxide. Our article discusses the material properties, rGO production and potential application.

You can read the full article here.