Drexel University's MXene material could help produce clean-burning hydrogen fuel
Hydrogen is one of the most abundant elements on Earth and an exceptionally clean fuel source. While it is making its way into the fuel cells of electric cars, busses and heavy equipment, its widespread use is hampered by the expensive gas-separation process required to produce pure hydrogen.
But that process could soon become more efficient and cost-effective thanks to a discovery by an international team of researchers, led in the U.S. by Drexel University. The group has uncovered exceptionally efficient gas separation properties in a nanomaterial called MXene that could be incorporated into the membranes used to purify hydrogen.
While hydrogen is present in a wide variety of molecules and materials in nature - water, a combination of hydrogen and water, foremost among them - it does not naturally exist in its pure elemental form - that is, hydrogen on its own, on Earth. To separate hydrogen from the other elements to which it commonly bonds, it requires introducing an electric current to excite and split apart the atoms in water molecules, or filtering a gaseous mixture containing hydrogen, through a membrane to separate the hydrogen from carbon dioxide or hydrocarbons.
The process of gas separation via membrane is the more effective and affordable option, so in recent years researchers have been ramping up efforts to develop membranes that can thoroughly and quickly filter out hydrogen.
A study recently published in the journal Nature Communications, indicates that using MXene material in gas-separation membranes could be the most efficient way to purify hydrogen gas. The research, led by Haihui Wang, PhD, a professor from South China University of Technology and Yury Gogotsi, PhD, Distinguished University and Bach professor in Drexel's College of Engineering, in the Department of Materials Science and Engineering, shows that the nanomaterial's two-dimensional structure enables it to selectively reject large gas molecules, while letting hydrogen slip between the layers.
"In this report we show how exfoliated two-dimensional MXene nanosheets can be used as building blocks to construct laminated membranes for gas separation for the first time," Gogotsi said. "We demonstrated this using model systems of hydrogen and carbon dioxide."
Working in collaboration with researchers from South China University of Technology and Jilin University, in China, and Leibniz University of Hannover, in Germany, the Drexel team reported that membranes created using MXene nanosheets outperform the top-of-the-line membrane materials currently in use - both in permeability and selectivity.
Many different kinds of membranes are currently in use throughout the energy industry, for example for purifying coolant water before it is released, and for refining natural gas before it is distributed for use. Gas separation facilities also use them to retrieve nitrogen and oxygen from the atmosphere. This study opens the door for an expanded use of membrane technology, with the possibility of tailoring the filtration devices to sift out a large number of gaseous molecules.
MXene's advantage over materials currently being used and developed for gas separation is that both its permeability and filtration selectivity are tied to its structure and chemical composition. By contrast, other membrane materials, such as graphene and zeolite, do their filtering only by physically trapping - or sieving - molecules in tiny grids and channels, like a net.
MXenes special filtration properties exist because they are created by chemically etching out layers from a solid piece of material, called a MAX phase. This process forms a structure that is more like a sponge, with slit pores of various sizes. Gogotsi's Nanomaterials Research Group, which has been working with MXenes since 2011, can predetermine the size of the channels by using different types of MAX phases and etching them with different chemicals.
The channels themselves can be created in a way that makes them chemically active, so they are able to attract - or adsorb - certain molecules as they pass through. Thus, a MXene membrane functions more like a magnetic net and it can be designed to trap a wide variety of chemical species as they pass through.
"This is one of the key advantages of MXenes," Gogotsi said. "We have dozens of MXenes available which can be tuned to provide selectivity to different gasses. We used titanium carbide MXene in this study, but there are at least two dozen other MXenes already available, and more are expected to be studied in the next couple of years - which means it could be developed for a number of different gas separation applications."
The versatile two-dimensional material, which was discovered at Drexel in 2011, has already shown its ability to improve efficiency of electric storage devices, stave off electromagnetic interference and even purify water. Studying its gas separation properties was the next logical step, according to Gogotsi.
"Our work on water filtration, the sieving of ions and molecules, and supercapacitors, which also involves ion sieving, suggested that gas molecules may also be sieved using MXene membranes with atomically thin channels between the MXene sheets," he said. "However, we were lacking experience in the gas separation field. This research would not have been possible without our Chinese collaborators, who provided the experience needed to achieve the goal and demonstrated that MXene membranes can efficiently separate gas mixtures."
In order for MXene to make its way into industrial membranes, Gogotsi's group will continue to improve its durability, chemical and temperature stability and reduce the cost of production.
Read the full paper here: https:/
Britt Faulstick | EurekAlert!
Graphene origami as a mechanically tunable plasmonic structure for infrared detection
25.04.2018 | University of Illinois College of Engineering
Scientists create innovative new 'green' concrete using graphene
24.04.2018 | University of Exeter
Magnetic resonance imaging, or MRI, is a widely used medical tool for taking pictures of the insides of our body. One way to make MRI scans easier to read is...
At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.
Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...
Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.
Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
26.04.2018 | Power and Electrical Engineering
26.04.2018 | Life Sciences
26.04.2018 | Power and Electrical Engineering