Photocatalysis using particles in water is a promising technology for generating fuels from sunlight. One major obstacle to producing these solar fuels cheaply and abundantly, though, is that it requires semiconductors that are efficient but prone to corrosion.
In a breakthrough that overcomes this challenge, the lab of Shu Hu, assistant professor of Chemical & Environmental Engineering, has found a solution with a first-of-its-kind coating. The results are published in the Proceedings of the National Academy of Sciences.
Water-splitting systems—which break water down to hydrogen and oxygen—need semiconductor materials with narrow bandgaps (a property allowing for absorbing more sunlight), which efficiently converts solar energy to chemical energy. While these materials can easily capture sunlight, they all corrode under illumination via self-reduction or self-oxidation. It’s a challenge that researchers have spent more than a half-century trying to solve. Strategies to protect these materials tend to limit their abilities to separate the charges of negative electrons and positive holes, a process that is essential to photocatalysis but harder to achieve than it is for other systems, such as solar cells. Typically, layers designed to guard these systems protect only one of the system’s two electrodes, namely the cathode or anode, limiting it to allow for the transport of either electron or hole—but not both.
Hydrogen has attracted extensive attention from academia and industry as an energy source due to its intrinsic environmental compatibility, abundance, and high energy density (120 MJ kg−1). Electrocatalytic water splitting is an environmentally friendly route to produce hydrogen, especially when the electricity is from renewable sources that minimize carbon dioxide emissions throughout the process.
Theoxygen evolution reaction (OER) on the anode and hydrogen evolution reaction (HER) on the cathode are two half-reactions in electrocatalytic water splitting. Pt- and Ru/Ir-based compounds are the best-known high-performance noble metal electrocatalysts for HER and OER, respectively. However, the scarcity and high cost of such noble metals hamper their application in water electrolysis. Therefore, with global prospects, it is essential to develop earth-abundant non-noble metal electrocatalysts for next-generation water splitting technologies. Recently, Ni-based electrocatalysts have been confirmed to be effective for boosting electrocatalytic water splitting, but their performances are not high enough for large-scale hydrogen production.
A team in China has successfully fabricated Mn-doped Ni2O3/Ni2P and Mn-doped NixSy/Ni2P through facile hydrothermal reaction and subsequently phosphorization and sulfurization method.
Combining bacterial genes, virus shell creates a highly efficient, renewable material used in generating power from water
Scientists at Indiana University have created a highly efficient biomaterial that catalyzes the formation of hydrogen – one half of the “holy grail” of splitting H2O to make hydrogen and oxygen for fueling cheap and efficient cars that run on water.
A modified enzyme that gains strength from being protected within the protein shell – or “capsid” – of a bacterial virus, this new material is 150 times more efficient than the unaltered form of the enzyme.
The process of creating the material was recently reported in “Self-assembling biomolecular catalysts for hydrogen production” in the journalNature Chemistry.
“Essentially, we’ve taken a virus’s ability to self-assemble myriad genetic building blocks and incorporated a very fragile and sensitive enzyme with the remarkable property of taking in protons and spitting out hydrogen gas,” said Trevor Douglas, the Earl Blough Professor of Chemistry in the IU Bloomington College of Arts and Sciences’ Department of Chemistry, who led the study. “The end result is a virus-like particle that behaves the same as a highly sophisticated material that catalyzes the production of hydrogen.”
Hydrogen gas, an important synthetic feedstock, is poised to play a key role in renewable energy technology; however, its credentials are undermined because most is currently sourced from fossil fuels, such as natural gas. A KAUST team has now found a more sustainable route to hydrogen fuel production using chaotic, light-trapping materials that mimic natural photosynthetic water splitting.
The complex enzymes inside plants are impractical to manufacture, so researchers have developed photocatalysts that employ high-energy, hot electrons to cleave water molecules into hydrogen and oxygen gas. Recently, nanostructured metals that convert solar electrons into intense, wave-like plasmon resonances have attracted interest for hydrogen production. The high-speed metal plasmons help transfer carriers to catalytic sites before they relax and reduce catalytic efficiency.
Getting metal nanoparticles to respond to the entire broadband spectrum of visible light is challenging. “Plasmonic systems have specific geometries that trap light only at characteristic frequencies,” explains Andrea Fratalocchi, who led the research. “Some approaches try to combine multiple nanostructures to soak up more colors, but these absorptions take place at different spatial locations so the sun’s energy is not harvested very efficiently.”
NASA Astronauts have relied upon hydrogen gas for decades and the element is essential for space travel. How? As a fuel source.
Hundreds of thousands of gallons of liquid hydrogen are utilized as rocket fuel to propel space shuttles into Earth orbit.
But the innovations don’t stop there. The research NASA has done is making way for hydrogen fuel cells that could one day be used for a variety of applications, from running your car to your cell phone.
When combined with oxygen to produce electric power, the only byproduct is pure water. Apparently, the water produced is “so clean that astronauts actually drink the water produced by fuel cells on the space shuttle.”
Though there are still problems and obstacles to overcome, hydrogen as a fuel has a promising future.
Researchers from the Nanomaterials by Design Group at University of Oxford, led by professor Nicole Grobert have produced millimetre-sized crystals of high-quality graphene in minutes, using a chemical vapour deposition technique (CVD).
The new method produces 2–3mm graphene crystals in 15 minutes, compared to current process which can take up to 19 hours.
Researchers took a thin film of silica deposited on a platinum foil which when heated, reacts to create a layer of platinum silicide. This layer melts at a lower temperature than platinum and silica to create a thin liquid layer that smooth’s out nanoscale ‘valleys’ in the platinum, so that carbon atoms in methane gas brushing the surface form large flakes of graphene.
Grobery, said, ‘Not only can we make millimetre-sized graphene flakes in minutes but this graphene is of a comparable quality to any other methods.’
The team believe the CVD technique could also have additional benefits claiming with a thicker liquid layer to insulate it the graphene might not have to be removed from the substrate before it can be used – an expensive and time consuming process.
Grobert added, ‘Of course a great deal more work is required before we get graphene technology, but we’re now on the cusp of seeing this material make the leap from the laboratory to a manufacturing setting, and we’re keen to work with industrial partners to make this happen.
The researchers hope to develop this technique further and produce flakes of graphene in large wafer-sized sheets.
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If you’re following the global effort to reach net-zero greenhouse gas emissions by 2050, you may notice a lot of people are assuming they’ll have access to low- or zero-emission hydrogen. Thing is, most H2 today is made from fossil fuels, and H2 production dumps 830 megatons of CO2 into the atmosphere each year, according to the International Energy Agency. Eric Lopato of Carnegie Mellon University is one of the chemists looking to change that. With advisor Stefan Bernhard, Lopato is investigating iridium-based compounds that can split water into H2 and O2 using sunlight. Various organic groups, called ligands, attached to the iridium core produce the range of colors seen in these 1-ml vials, a result of the unique way each compound interacts with light. — Craig Bettenhausen
Caltech researchers have made a discovery that they say could lead to the economically viable production of solar fuels in the next few years.
For years, solar-fuel research has focused on developing catalysts that can split water into hydrogen and oxygen using only sunlight. The resulting hydrogen fuel could be used to power motor vehicles, electrical plants, and fuel cells. Since the only thing produced by burning hydrogen is water, no carbon pollution is added to the atmosphere.
In 2014, researchers in the lab of Harry Gray, Caltech’s Arnold O. Beckman Professor of Chemistry, developed a water-splitting catalyst made of layers of nickel and iron. However, no one was entirely sure how it worked. Many researchers hypothesized that the nickel layers, and not the iron atoms, were responsible for the water-splitting ability of the catalyst (and others like it).
To find out for sure, Bryan Hunter (PhD ‘17), a former fellow at the Resnick Institute, and his colleagues in Gray’s lab created an experimental setup that starved the catalyst of water. “When you take away some of the water, the reaction slows down, and you are able to take a picture of what’s happening during the reaction,” he says.
New experiments demonstrate the potential for diamond as a material for spintronics
Conventional electronics rely on controlling electric charge. Recently, researchers have been exploring the potential for a new technology, called spintronics, that relies on detecting and controlling a particle’s spin. This technology could lead to new types of more efficient and powerful devices.
In a paper published in Applied Physics Letters, from AIP Publishing, researchers measured how strongly a charge carrier’s spin interacts with a magnetic field in diamond. This crucial property shows diamond as a promising material for spintronic devices.
Diamond is attractive because it would be easier to process and fabricate into spintronic devices than typical semiconductor materials, said Golrokh Akhgar, a physicist at La Trobe University in Australia. Conventional quantum devices are based on multiple thin layers of semiconductors, which require an elaborate fabrication process in an ultrahigh vacuum.
“Diamond is normally an extremely good insulator,” Akhgar said. But, when exposed to hydrogen plasma, the diamond incorporates hydrogen atoms into its surface. When a hydrogenated diamond is introduced to moist air, it becomes electrically conductive because a thin layer of water forms on its surface, pulling electrons from the diamond. The missing electrons at the diamond surface behave like positively charged particles, called holes, making the surface conductive.
Scientists have developed a new low-temperature catalyst for producing high-purity hydrogen gas while simultaneously using up carbon monoxide (CO). The discovery-described in a paper set to publish online in the journal Science on Thursday, June 22, 2017-could improve the performance of fuel cells that run on hydrogen fuel but can be poisoned by CO.
“Thiscatalyst produces a purer form of hydrogen to feed into the fuel cell,” said José Rodriguez, a chemist at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory. Rodriguez and colleagues in Brookhaven’s Chemistry Division-Ping Liu and Wenqian Xu-were among the team of scientists who helped to characterize the structural and mechanistic details of the catalyst, which was synthesized and tested by collaborators at Peking University in an effort led by Chemistry Professor Ding Ma.
Because the catalyst operates at low temperature and low pressure to convert water (H2O) and carbon monoxide (CO) to hydrogen gas (H2) and carbon dioxide (CO2), it could also lower the cost of running this so-called “water gas shift” reaction.
“With low temperature and pressure, the energy consumption will be lower and the experimental setup will be less expensive and easier to use in small settings, like fuel cells for cars,” Rodriguez said.
It’s easy to get lost following the intricate, looping, twisting filaments in this detailed image of supernova remnant Simeis 147 or, as it’s better known as, the Spaghetti Nebula. Seen about 3,000 light years away, toward the boundary of the constellations Taurus and Auriga, it covers nearly 3 degrees or 6 full moons on the sky- about 150 light-years wide. This composite image includes data taken through narrow-band filters where the reddish emission is from ionized hydrogen atoms and doubly ionized oxygen atoms is in faint blue-green hues. The supernova remnant has an estimated age of about 40,000 years, meaning light from the massive stellar explosion first reached Earth 40,000 years ago. But the expanding remnant is not the only aftermath. The cosmic catastrophe also left behind a spinning neutron star, or pulsar. It’s all that remains of the original star’s core.
The Ring Nebula (M57), is more complicated than it appears through a small telescope. The easily visible central ring is about one light-year across, but this remarkably deep exposure shows in detail the looping filaments of glowing gas extending much farther from the nebula’s central star. This image, taken by combining data from three different large telescopes, includes red light emitted by hydrogen as well as visible and infrared light. The Ring Nebula is an elongated planetary nebula, a type of nebula created when a Sun-like star evolves to throw off its outer atmosphere to become a white dwarf star. The Ring Nebula is about 2,500 light-years away from us here on Earth.
Image Credit: Hubble, Large Binocular Telescope, Subaru Telescope; Composition & Copyright: Robert Gendler
A rainbow airglow! Air glows all of the time, but it is usually hard to see. A disturbance, like a storm, may cause noticeable rippling in the Earth’s atmosphere. These gravity waves are oscillations in air, just like the ripples created when a rock is thrown in calm water. Makes sense right? But where do the colors come from? The deep red glow likely originates from OH molecules excited by ultraviolet light from the Sun. The orange and green airglow is likely caused by sodium and oxygen atoms slightly higher up. A spectacular sky is visible through this airglow, with the central band of our Milky Way Galaxy running up the image center, and M31, the Andromeda Galaxy, visible near the top left.
University of Houston Texas Center for Superconductivity Director,Zhifeng Ren. Image credit: University of Houston.
By Anthony Caggiano
A new catalyst has enabled hydrogen to be made from seawater.
University of Houston, USA, researchers found combining an oxygen and a hydrogen evolution reaction catalyst together achieved current densities capable of supporting industrial demands while requiring relatively low voltage to start seawater electrolysis.
The researchers said the device, made with non-noble metal nitrides, avoids obstacles that have made it difficult to make hydrogen or safe drinking water from seawater.
University of Houston Texas Center for Superconductivity Director, Zhifeng Ren, said a major issue had been that there wasn’t a catalyst that could split seawater to produce hydrogen without also setting free ions of sodium, chlorine, calcium and other components of seawater, which once freed can settle on the catalyst and render it inactive. Chlorine ions are especially challenging, in part because chlorine requires only a slightly higher voltage to free than is needed to free hydrogen.
The researchers designed and synthesised a 3D core-shell oxygen evolution reaction catalyst using transition metal-nitride, with nanoparticles made of a nickle-iron-nitride compound and nickle-molybdenum-nitride nanorods on porous nickle foam.
University of Houston Postdoctoral Researcher and first paper author, Luo Yu, said the new oxygen evolution reaction catalyst was paired with a hydrogen one of nickle-molybdenum-nitride nanorods.
The catalysts were integrated into a two-electrode alkaline electrolyser, which can be powered by waste heat via a thermoelectric device or by an AA battery.
Cell voltages required to produce a current density of 100 milliamperes per square centimetre (a measure of current density, or mA cm-2) ranged from 1.564V to 1.581V.
The voltage is significant, Yu said, because while a voltage of at least 1.23V is required to produce hydrogen, chlorine is produced at a voltage of 1.73V, meaning the device had to be able to produce meaningful levels of current density with a voltage between the two levels.
The researchers tested the catalysts with seawater drawn from Galveston Bay, off the Texas coast. Ren said it also would work with wastewater.
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In November 2020, the UK is set to host the major UN Climate Change summit; COP26. This will be the most important climate summit since COP21 where the Paris Agreement was agreed. At this summit, countries, for the first time, can upgrade their emission targets through to 20301. In the UK, current legislation commits government to reduce greenhouse gas emissions by at least 100% of 1990 levels by 2050, under the Climate Change Act 2008 (2050 Target Amendment)2.
Hydrogen has been recognised as a low-carbon fuel which could be utilised in large-scale decarbonisation to reach ambitious emission targets. Upon combustion with air, hydrogen releases water and zero carbon dioxide unlike alternative heavy emitting fuels. The potential applications of hydrogen span across an array of heavy emitting sectors. The focus of this blog is to highlight some of these applications, and on-going initiatives, across the following three sectors: Industry, Transport and Domestic.
Please click (here3) to access our previous SCI Energy Group blog centred around UK CO2emissions.
Figure 1: climate change activists
Industry
Did you know that small-scale hydrogen boilers already exist?4
Through equipment modification, it is technically feasible to use clean hydrogen fuel across many industrial sectors such as: food and drink, chemical, paper and glass.
Whilst this conversion may incur significant costs and face technical challenges, it is thought that hydrogen-fuelled equipment such as furnaces, boilers, ovens and kilns may be commercially available from the mid-2020’s4.
Figure 2: gas hydrogen peroxide boiler line vector icon
Domestic
Did you know that using a gas hob can emit up to or greater than 71 kg of CO2per year?5
Hydrogen could be supplied fully or as a blend with natural gas to our homes in order to minimise greenhouse gas emissions associated with the combustion of natural gas.
As part of the HyDeploy initiative, Keele University, which has its own private gas network, have been receiving blended hydrogen as part of a trial study with no difference noticed compared to normal gas supply6.
Other initiatives such as Hydrogen 1007 and HyDeploy8are testing the feasibility of delivering 100% hydrogen to homes and commercial properties.
Figure 3: gas burners
Transport
Did you know that, based on an average driving distance of approximately 11,500 miles per annum, an average vehicle will emit approximately 4.6 tonnes of CO2per year?9
In the transport sector, hydrogen fuel can be utilised in fuel cells, which convert hydrogen and oxygen into water and electricity.
Hydrogen fuel cell vehicles are already commercially available in the UK. However, currently, form only a small percentage of Ultra Low Emission Vehicle (ULEV) uptake10.
Niche applications of hydrogen within the transport sector are expected to show greater potential for hydrogen such as buses and trains. Hydrogen powered buses are already operational in certain parts of the UK and hydrogen trains are predicted to run on British railways from as early as 202211.
Figure 4: h2 combustion engine for emission free ecofriendly transport
Summary
This blog gives only a brief introduction to the many applications of hydrogen and its decarbonisation potential. The purpose of which, is to highlight that hydrogen, amongst other low-carbon fuels and technologies, can play an important role in the UK’s transition to net-zero emissions.
Stay tuned for further SCI Energy Group blogs which will continue to highlight alternative low-carbon technologies and their potential to decarbonise.
Reace Edwards is a member of SCI’s Energy group and a PhD Chemical Engineering student at the University of Chester. Read more about her involvement with SCI here or watch her recent TEDx Talk here.
The Horsehead nebula. This light years tall Dark dust cloud is silhouetted by ionized hydrogen gas. The nebula is 1500 light years away near the easternmost star of Orion’s belt, and is an active star forming region.
