A three-dimensional honeycomb of hexagonally arranged carbon has been termed 3D graphene.
3D Graphene
3D graphene, also known as a graphene aerogel or a three-dimensional graphene nanostructure, is characterized by its porous and three-dimensional framework. Graphene, in its essence, consists of a single layer of carbon atoms arranged in a hexagonal pattern. In contrast, when multiple layers of graphene are stacked, it forms graphite, a common material used as the “lead” in pencils. However, graphite’s mechanical properties are relatively weak due to the close stacking of graphene sheets. To address this limitation, a porous variation of graphene, namely graphene aerogel, can be produced by introducing air-filled pores between the graphene sheets. This unique structure allows the three-dimensional graphene to maintain the exceptional properties of graphene while enhancing its mechanical robustness.
3D graphene, often referred to as 3D graphene foam or graphene aerogel, is a three-dimensional structure composed of graphene, a single layer of carbon atoms arranged in a hexagonal lattice. While traditional graphene is a two-dimensional material, 3D graphene extends into the third dimension, forming a porous and lightweight structure.
The creation of 3D graphene typically involves the following steps:
Graphene Oxide Production: Graphene oxide is derived from graphite, and it contains oxygen-functional groups, making it easier to disperse in solvents.
Reduction: The graphene oxide is reduced, removing some of the oxygen functional groups to restore the electrical conductivity of the material.
Self-Assembly: The reduced graphene oxide sheets self-assemble into a three-dimensional network through various methods, such as freeze-drying or chemical reduction.
The resulting 3D graphene structure has several notable properties and applications:
Lightweight and Porous: 3D graphene is extremely lightweight and porous, making it an ideal material for applications where weight reduction is crucial, such as aerospace and materials for batteries and supercapacitors.
High Surface Area: Its large surface area allows for enhanced adsorption and catalytic activity, making it valuable in applications like environmental remediation, water purification, and gas adsorption.
Mechanical Strength: 3D graphene exhibits good mechanical strength, which is useful for structural applications and can be incorporated into composites.
Thermal and Electrical Conductivity: It maintains excellent thermal and electrical conductivity, making it useful in applications like heat sinks and electronic devices.
Energy Storage: 3D graphene can be used to create high-performance energy storage devices like supercapacitors and batteries, due to its excellent electrical conductivity and large surface area.
Sensors: It can be used to create highly sensitive sensors for various gases and molecules.
Catalyst Support: 3D graphene can serve as a support for catalyst materials, improving their performance in chemical reactions.
3D graphene’s unique properties make it a promising material for a wide range of applications, and ongoing research continues to explore its potential in various fields, including materials science, electronics, energy storage, and environmental engineering.
Additive Manufacturing (AM) is an umbrella term for a collection of several technologies. Most AM is simply 2D printing processes repeated in an iterative fashion to build up a 3-dimensional part. AM begins with a computer dissecting a 3-D digital model (also called CAD data) of the desired end product into thin wafers and then building these wafers using plastics or other materials layer by layer into the final part. Graphene’s role in AM is increase the number benefits to the final product or improve on the performance of today’s products as well as mitigating or reducing the negatives
Additive Manufacturing (AM) is an umbrella term for a collection of several technologies. Most AM is simply 2D printing processes repeated in an iterative fashion to build up a 3-dimensional part. AM begins with a computer dissecting a 3-D digital model (also called CAD data) of the desired end product into thin wafers and then building these wafers using plastics or other materials layer by layer into the final part. Graphene’s role in AM is increase the number benefits to the final product or improve on the performance of today’s products as well as mitigating or reducing the negatives.
AMO is a dynamic and application-oriented research institute based in Aachen, Germany, with world-class expertise in graphene electronics, nanophotonics, nanostructuring, sensor technology and perovskite optoelectronics. We do research to translate the latest advancements of nanotechnology into new applications and to develop innovative solutions to meet the challenges of tomorrow.
AMO GmbH (Germany)
Since 1993, we have been pioneering innovations at the intersection between academic and industrial research, working jointly with national and international partners from industry, academia, SMEs and start-ups.
Research at the highest level
AMO is a non-profit research institute in the field of nanotechnology. We investigate cutting-edge technologies to meet the challenges of our society – be it in the fields of information technology, energy and the environment, or health and safety. Through our research, we develop the technologies of tomorrow.
We work mainly on publicly funded research projects and make an important contribution to German and European R&D programmes. We are also involved in bilateral projects with innovators looking for a strong partner in nanotechnology.
Our research team is diverse and dynamic, consisting of a strong core of experienced researchers and technicians, Masters and PhD students and post-docs.
The microelectronics industry uses anodic bonding to bond silicon wafers to glass to protect them from humidity or contaminations. When employing this technique to produce graphene, graphite is first pressed onto a glass substrate. Then a high voltage is applied between the graphite and a metal back contact, and the glass substrate is then heated.
Ball milling is a process for grinding a material. It involves A slightly inclined or horizontal rotating cylinder that is partially filled with balls,which grind material to the necessary fineness by friction and impact with the tumbling balls. A ball-milling treatment can help to fabricate graphene composites of variety of matrixes.
A bandgap is an energy range in which electrons cannot exist. A bandgap is required to enable electronic switching. Semiconductor materials like silicon are used in electronics because while it conducts it electrons, it can also act as an insulator–it has a bandgap. Graphene without any alteration does not have a bandgap, making it a pure conductor.
This is simply two layers of graphene. This type of graphene was synthesized by Geim and Novosolev in their first experiments and would fall into the category of Very Few Layers (VFL) graphene.
A biosensor is an analytical device that can detect a biomolecule-related element with an appropriate transducer to generate a measurable signal from the sample. In general, graphene possesses attractive qualities for sensors and biosensors, such as ultra-high charge mobility, transparency, large surface area, non-toxicity, high-tensile strength and high thermal conductivity to name a few. However, for graphene to maintain these properties, it has to be kept in a pretty pure form.
Black phosphorus is the thermodynamically stable form of phosphorus at room temperature and pressure. In 2014, researchers were able to exfoliate the material to thin films just 10 to 20 atoms thick. Not only does it have an inherent bandgap unlike graphene, but that bandgap is also highly tunable, depending on the number of layers used. However, the property that really sets black phosphorus apart from graphene and nearly all two-dimensional materials is its intrinsically strong, in-plane anisotropy. That means its properties are directionally dependent, like the grain of a piece of wood.
Bottom-up manufacturing involves building up your product up, atom by atom, often through guided self-assembly. CVD deposition techniques would be considered bottom-up manufacturing because the layers grow themselves.
Bulk supply is a term that is associated with applications that require material levels reaching many tons per year of graphene, such as nanocomposite inks. This means that the costs of these materials are much lower and therefore lower grades of graphene.
This is a method for producing graphene. The rGO technique and its variants are based on the Brodie method, which was later developed into the Hummers method and subsequent variants. rGO employs graphite as a feedstock in which it is mixed with sulfuric acid to serve as an intercalating agent and potassium permanganate as an oxidant. This mixture is heated at high temperatures to produce graphene oxide (GO). At this point, the GO is reduced to graphene either chemically or thermally and with further steps of sonication, rinsing and dispersion.
Coal is a sedimentary deposit composed predominantly of carbon that is readily combustible. Coal is black or brownish-black, and has a composition that (including inherent moisture) consists of more than 50 percent by weight and more than 70 percent by volume of carbonaceous material. It is formed from plant remains that have been compacted, hardened, chemically altered, and metamorphosed by heat and pressure over geologic time.
Coal is a combustible black or brownish-black sedimentary rock with a high amount of carbon and hydrocarbons. Coal is classified as a nonrenewable energy source because it takes millions of years to form. Coal contains the energy stored by plants that lived hundreds of millions of years ago in swampy forests.
Layers of dirt and rock covered the plants over millions of years. The resulting pressure and heat turned the plants into the substance we call coal.
Coal is found all over the world—including the United States—predominantly in places where prehistoric forests and marshes existed before being buried and compressed over millions of years. Some of the largest coal deposits are located in the Appalachian basin in the eastern U.S., the Illinois basin in the mid-continent region, and throughout numerous basins and coal fields in the western U.S. and Alaska.
What are the types of coal?
There are four major types (or “ranks”) of coal. Rank refers to steps in a slow, natural process called “coalification,” during which buried plant matter changes into an ever denser, drier, more carbon-rich, and harder material. The four ranks are:
Anthracite: The highest rank of coal. It is a hard, brittle, and black lustrous coal, often referred to as hard coal, containing a high percentage of fixed carbon and a low percentage of volatile matter.
Bituminous: Bituminous coal is a middle rank coal between subbituminous and anthracite. Bituminous coal usually has a high heating (Btu) value and is used in electricity generation and steel making in the United States. Bituminous coal is blocky and appears shiny and smooth when you first see it, but look closer and you might see it has thin, alternating, shiny and dull layers.
Subbituminous: Subbituminous coal is black in color and is mainly dull (not shiny). Subbituminous coal has low-to-moderate heating values and is mainly used in electricity generation.
Lignite: Lignite coal, aka brown coal, is the lowest grade coal with the least concentration of carbon. Lignite has a low heating value and a high moisture content and is mainly used in electricity generation.
The precursor to coal is peat. Peat is a soft, organic material consisting of partly decayed plant and mineral matter. When peat is placed under high pressure and heat, it undergoes physical and chemical changes (coalification) to become coal.
Coal is classified into four main types, or ranks: anthracite, bituminous, subbituminous, and lignite. The ranking depends on the types and amounts of carbon the coal contains and on the amount of heat energy the coal can produce. The rank of a coal deposit is determined by the amount of pressure and heat that acted on the plants over time.
Anthracite contains 86%–97% carbon and generally has the highest heating value of all ranks of coal. Anthracite accounted for less than 1% of the coal mined in the United States in 2022. All anthracite mines in the United States are in northeastern Pennsylvania. In the United States, anthracite is mainly used by the metals industry.
Bituminous coal contains 45%–86% carbon. Bituminous coal in the United States is between 100 million and 300 million years old. Bituminous coal is the most abundant rank of coal found in the United States, and it accounted for about 46% of total U.S. coal production in 2022. Bituminous coal is used to generate electricity and is an important fuel and raw material for making coking coal for the iron and steel industry. Bituminous coal was produced in at least 16 states in 2022, but five states accounted for about 78% of total bituminous production. The top five bituminous producing states and their percentage share of total U.S. bituminous production in 2022 were:
West Virginia—31%
Illinois—14%
Pennsylvania—14%
Kentucky—11%
Indiana—9%
Subbituminous coal typically contains 35%–45% carbon, and it has a lower heating value than bituminous coal. Most subbituminous coal in the United States is at least 100 million years old. In 2022, subbituminous coal accounted for about 46% of total U.S. coal production. The five subbituminous producing states and their percentage share of total U.S. subbituminous production in 2022 were:
Wyoming—89%
Montana—8%
New Mexico—2%
Colorado—2%
Alaska—<1%
Lignite contains 25%–35% carbon and has the lowest energy content of all coal ranks. Lignite coal deposits tend to be relatively young and were not subjected to extreme heat or pressure. Lignite is crumbly and has high moisture content, which contributes to its low heating value. In 2022, five states produced lignite, which accounted for 8% of total U.S. coal production. The five lignite-producing states and their percentage share of total U.S. lignite production in 2022 were:
North Dakota—56%
Texas—36%
Mississippi—7%
Louisiana—1%
Montana—<1%
The Great Plains Synfuels Plant in North Dakota converts lignite to synthetic natural gas that is sent in natural gas pipelines to consumers in the eastern United States.
What is coal used for?
Coal is primarily used as fuel to generate electric power in the United States. In coal-fired power plants, bituminous coal, subbituminous coal, or lignite is burned. The heat produced by the combustion of the coal is used to convert water into high-pressure steam, which drives a turbine, which produces electricity. In 2019, about 23 percent of all electricity in the United States was generated by coal-fired power plants, according to the U.S. Energy Information Administration.
Certain types of bituminous coal can also be used in making steel. Coal used for steel making needs to be high in carbon content and low in moisture, ash, sulfur, and phosphorous content. Coal that meets these specifications is known as metallurgical coal. Coal also has a myriad of other uses, including in cement production, carbon fibers and foams, medicines, tars, synthetic petroleum-based fuels, and home and commercial heating.
Which country has the most coal?
As of January 2020, the United States has the largest recoverable coal reserves with an estimated 252 billion short tons of coal remaining, according to the U.S. Energy Information Administration.
What is the biggest coal deposit in the United States?
The biggest coal deposit by volume is the Powder River Basin in Wyoming and Montana, which the USGS estimated to have 1.07 trillion short tons of in-place coal resources, 162 billion short tons of recoverable coal resources, and 25 billion short tons of economic coal resources (also called reserves) in 2013.
The coal in the Powder River Basin is subbituminous in rank. Large coal deposits can also be found in the Williston Basin in North Dakota and Montana (lignite in rank), the Appalachian Basin in Ohio, Pennsylvania, West Virginia, Virginia, and Alabama (bituminous in rank), and the Illinois Basin in Illinois and Indiana (bituminous in rank).
Global Coal Consumption
Global coal consumption has continued to rise, reaching new record levels in recent years.
Global Coal Consumption Trends
2023: Global coal demand reached an all-time high of approximately 8.70 billion tonnes, marking a 2.6% increase from the previous year.
2024: Estimates indicate that coal consumption further increased to around 8.77 billion tonnes, setting another record.
Regional Consumption Patterns
Asia: Over 80% of global coal consumption occurred in Asia in 2023.China and India were the primary contributors, with China’s consumption increasing by 4.9% and India’s by 8%.
Europe and the United States: Both regions experienced significant declines in coal consumption in 2023, with the European Union decreasing by 23% and the United States by 21%.
Future Outlook
The International Energy Agency (IEA) projects that global coal demand will plateau through 2027, remaining close to current record levels.Despite the expansion of renewable energy, coal continues to be a dominant energy source, particularly in developing economies.
Conductive ink is an ink that results in a printed object capable of conducting electricity. Graphene based conductive inks have been around commercially since at least as early as 2009. Graphene based inks are generally significantly cheaper than silver and copper based inks.
Chemical vapour deposition, or CVD, is a method which can produce relatively high quality graphene, potentially on a large scale. The CVD process is reasonably straightforward, although some specialist equipment is necessary, and in order to create good quality graphene it is important to strictly adhere to guidelines set concerning gas volumes, pressure, temperature, and time duration.
Materials based on graphene oxide are under development for use in dental composites. The expectation is that they will lead to fixed dental prostheses with increased longevity and improved clinical function.
Dielectric Barrier Discharge (DBD) plasma reactors are a type of reactor that has recently been used by industry to produce graphene commercially.
In contrast to other methods, DBD plasma reactors lead to a standalone graphene product.
The other methods employ plasma-assisted methods that are more applicable to academic interests or are restricted to deposition onto a specific surface.
