- Snam chief says company to inject more hydrogen into system
- Market could be worth $2.5 trillion if industry embraces gasThe
THE CEO Who Wants Italy to Love Hydrogen Power
THE CEO Who Wants Italy to Love Hydrogen Power
This is a schematic illustration of Hybrid Na-CO2 System and its reaction mechanism. UNIST
Scientists from the Ulsan National Institute of Science and Technology (UNIST) developed a system which can continuously produce electrical energy and hydrogen by dissolving carbon dioxide in an aqueous solution.
The inspiration came from the fact that much of the carbon dioxide produced by humans is absorbed by the oceans, where it raises the level of acidity in the water.
Researchers used this concept to “melt” carbon dioxide in water in order to induce an electrochemical reaction. When acidity rises, the number of protons increases, and these protons attract electrons at a high rate. This can be used to create a battery system where electricity is produced by removing carbon dioxide.
The elements of the battery system are similar to a fuel cell, and include a cathode (sodium metal), a separator (NASICON), and an anode (catalyst). In this case, the catalysts are contained in the water and are connected to the cathode through a lead wire. The reaction begins when carbon dioxide is injected into the water and begins to break down into electricity and hydrogen. Not only is the electricity generated obviously useful, but the produced hydrogen could be used to fuel vehicles as well. The current efficiency of the system is up to 50 percent of the carbon dioxide being converted, which is impressive, although the system only operates on a small scale.
“Carbon capture, utilization, and sequestration (CCUS) technologies have recently received a great deal of attention for providing a pathway in dealing with global climate change,” Professor Guntae Kim of the School of Energy and Chemical Engineering at UNIST said in a statement. “The key to that technology is the easy conversion of chemically stable CO2 molecules to other materials. Our new system has solved this problem with [the] CO2 dissolution mechanism.”
A nanostructured composite material developed at UC Santa Cruz has shown impressive performance as a catalyst for the electrochemical splitting of water to produce hydrogen. An efficient, low-cost catalyst is essential for realizing the promise of hydrogen as a clean, environmentally friendly fuel.
Researchers led by Shaowei Chen, professor of chemistry and biochemistry at UC Santa Cruz, have been investigating the use of carbon-based nanostructured materials as catalysts for the reaction that generates hydrogen from water. In one recent study, they obtained good results by incorporating ruthenium ions into a sheet-like nanostructure composed of carbon nitride. Performance was further improved by combining the ruthenium-doped carbon nitride with graphene, a sheet-like form of carbon, to form a layered composite.
“The bonding chemistry of ruthenium with nitrogen in these nanostructured materials plays a key role in the high catalytic performance,” Chen said. “We also showed that the stability of the catalyst is very good.”
The new findings were published in ChemSusChem, a top journal covering sustainable chemistry and energy materials, and the paper is featured on the cover of the January 10 issue. First author Yi Peng, a graduate student in Chen’s lab, led the study and designed the cover image.
Hydrogen has long been attractive as a clean and renewable fuel. A hydrogen fuel cell powering an electric vehicle, for example, emits only water vapor. Currently, however, hydrogen production still depends heavily on fossil fuels (mostly using steam to extract it from natural gas). Finding a low-cost, efficient way to extract hydrogen from water through electrolysis would be a major breakthrough. Electricity from renewable sources such as solar and wind power, which can be intermittent and unreliable, could then be easily stored and distributed as hydrogen fuel.
Currently, the most efficient catalysts for the electrochemical reaction that generates hydrogen from water are based on platinum, which is scarce and expensive. Carbon-based materials have shown promise, but their performance has not come close to that of platinum-based catalysts.
In the new composite material developed by Chen’s lab, the ruthenium ions embedded in the carbon nitride nanosheets change the distribution of electrons in the matrix, creating more active sites for the binding of protons to generate hydrogen. Adding graphene to the structure further enhances the redistribution of electrons.
“The graphene forms a sandwich structure with the carbon nitride nanosheets and results in further redistribution of electrons. This gives us greater proton reduction efficiencies,” Chen said.
The electrocatalytic performance of the composite was comparable to that of commercial platinum catalysts, the authors reported. Chen noted, however, that researchers still have a long way to go to achieve cheap and efficient hydrogen production.
In addition to Peng and Chen, coauthors of the study include Wanzhang Pan and Jia-En Liu at UC Santa Cruz and Nan Wang at South China University of Technology. This work was supported by the National Science Foundation and the NASA-funded Merced Nanomaterials Center for Energy and Sensing.
Hydrogen-powered vehicles are slowly hitting the streets, but although it’s a clean and plentiful fuel source, a lack of infrastructure for mass producing, distributing and storing hydrogen is still a major roadblock.
But new work out of the University of California, Los Angeles (UCLA) could help lower the barrier to entry for consumers, with a device that uses sunlight to produce both hydrogen and electricity.
The UCLA device is a hybrid unit that combines a supercapacitor with a hydrogen fuel cell, and runs the whole shebang on solar power.
Along with the usual positive and negative electrodes, the device has a third electrode that can either store energy electrically or use it to split water into its constituent hydrogen and oxygen atoms – a process called water electrolysis.
To make the electrodes as efficient as possible, the team maximized the amount of surface area that comes into contact with water, right down to the nanoscale. That increases the amount of hydrogen the system can produce, as well as how much energy the supercapacitor can store.
“People need fuel to run their vehicles and electricity to run their devices,” says Richard Kaner, senior author of the study. “Now you can make both fuel and electricity with a single device.”
Hydrogen itself may be clean, but producing it on a commercial scale might not be. It’s often created by converting natural gas, which not only results in a lot of carbon dioxide emissions but can be costly.
Using renewable sources like solar can help solve both of those problems at once. And it helps that the UCLA device uses materials like nickel, iron and cobalt, which are much more abundant than the precious metals like platinum that are currently used to produce hydrogen.
“Hydrogen is a great fuel for vehicles: It is the cleanest fuel known, it’s cheap and it puts no pollutants into the air – just water,” says Kaner. “And this could dramatically lower the cost of hydrogen cars.”
The new system could also help solve some of the infrastructure woes as well. Hydrogen vehicles can’t really take off until consumers can easily find places to fill up, and while strides are being made in that department, with the UCLA device users can hook into the sun almost anywhere to produce their own fuel, which could be particularly handy for those living in rural or remote areas.
As an added bonus, the supercapacitor part of the system can chemically store the harvested solar energy as hydrogen. Doing so could help bolster energy storage for the grid. Although the current device is palm-sized, the researchers say that it should be relatively easy to scale up for those applications.
The research was published in the journal Energy Storage Materials.
Credit: CC0 Public Domain
Researchers have developed a solar paint that can absorb water vapour and split it to generate hydrogen – the cleanest source of energy.
The paint contains a newly developed compound that acts like silica gel, which is used in sachets to absorb moisture and keep food, medicines and electronics fresh and dry.
But unlike silica gel, the new material, synthetic molybdenum-sulphide, also acts as a semi-conductor and catalyses the splitting of water atoms into hydrogen and oxygen.
Lead researcher Dr Torben Daeneke, from RMIT University in Melbourne, Australia, said: “We found that mixing the compound with titanium oxide particles leads to a sunlight-absorbing paint that produces hydrogen fuel from solar energy and moist air.
“Titanium oxide is the white pigment that is already commonly used in wall paint, meaning that the simple addition of the new material can convert a brick wall into energy harvesting and fuel production real estate.
“Our new development has a big range of advantages,” he said. “There’s no need for clean or filtered water to feed the system. Any place that has water vapour in the air, even remote areas far from water, can produce fuel.”
His colleague, Distinguished Professor Kourosh Kalantar-zadeh, said hydrogen was the cleanest source of energy and could be used in fuel cells as well as conventional combustion engines as an alternative to fossil fuels.
“This system can also be used in very dry but hot climates near oceans. The sea water is evaporated by the hot sunlight and the vapour can then be absorbed to produce fuel.
“This is an extraordinary concept – making fuel from the sun and water vapour in the air.”
More information: Torben Daeneke et al, Surface Water Dependent Properties of Sulfur-Rich Molybdenum Sulfides:
Electrolyteless Gas Phase Water Splitting, ACS Nano (2017). DOI: 10.1021/acsnano.7b01632
Provided by: RMIT University
“The solar energy business has been trying to overcome … challenge for years. The cost of installing solar panels has fallen dramatically but storing the energy produced for later use has been problematic.”
“In a single hour, the amount of power from the sun that strikes the Earth is more than the entire world consumes in an year.” To put that in numbers, from the US Department of Energy
Each hour 430 quintillion Joules of energy from the sun hits the Earth. That’s 430 with 18 zeroes after it! In comparison, the total amount of energy that all humans use in a year is 410 quintillion Joules. For context, the average American home used 39 billion Joules of electricity in 2013.
Clearly, we have in our sun “a source of unlimited renewable energy”. But how can we best harness this resource? How can we convert and “store” this energy resource on for sun-less days or at night time … when we also have energy needs?
Now therein lies the challenge!
Would you buy a smartphone that only worked when the sun was shining? Probably not. What it if was only half the cost of your current model: surely an upgrade would be tempting? No, thought not.
The solar energy business has been trying to overcome a similar challenge for years. The cost of installing solar panels has fallen dramatically but storing the energy produced for later use has been problematic.
Now scientists in Sweden have found a new way to store solar energy in chemical liquids. Although still in an early phase, with niche applications, the discovery has the potential to make solar power more practical and widespread.
Until now, solar energy storage has relied on batteries, which have improved in recent years. However, they are still bulky and expensive, and they degrade over time.
Trap and release solar power on demand
A research team from Chalmers University of Technology in Gothenburg made a prototype hybrid device with two parts. It’s made from silica and quartz with tiny fluid channels cut into both sections.
The top part is filled with a liquid that stores solar energy in the chemical bonds of a molecule. This method of storing solar energy remains stable for several months. The energy can be released as heat whenever it is required.
The lower section of the device uses sunlight to heat water which can be used immediately. This combination of storage and water heating means that over 80% of incoming sunlight is converted into usable energy.
Suddenly, solar power looks a lot more practical. Compared to traditional battery storage, the new system is more compact and should prove relatively inexpensive, according to the researchers. The technology is in the early stages of development and may not be ready for domestic and business use for some time.
From the lab to off-grid power stations or satellites?
The researchers wrote in the journal Energy & Environmental Science: “This energy can be transported, and delivered in very precise amounts with high reliability(…) As is the case with any new technology, initial applications will be in niches where [molecular storage] offers unique technical properties and where cost-per-joule is of lesser importance.”
The team now plans to test the real-world performance of the technology and estimate how much it will cost. Initially, the device could be used in off-grid power stations, extreme environments, and satellite thermal control systems.
Editor’s Note: As Solomon wrote in Ecclesiastes 1:9: “What has been will be again, what has been done will be done again; there is nothing new under the sun.”
Storing Solar Energy chemically and converting ‘waste heat’ has and is the subject of many research and implementation Projects around the globe. Will this method prove to be “the one?” This writer (IMHO) sees limited application, but not a broadly accepted and integrated solution.
Solar Energy to Hydrogen Fuel
So where does that leave us? We have been following the efforts of a number of Researchers/ Universities who are exploring and developing “Sunlight to Hydrogen Fuel” technologies to harness the enormous and almost inexhaustible energy source power-house … our sun! What do you think? Please leave us your Comments and we will share the results with our readers!
We have written and posted extensively about ‘Solar to Hydrogen Renewable Energy’ – here are some of our previous Posts:
Researchers at Rice University are on to a relatively simple, low-cost way to pry hydrogen loose from water, using the sun as an energy source. The new system involves channeling high-energy “hot” electrons into a useful purpose before they get a chance to cool down. If the research progresses, that’s great news for the hydrogen […]
HyperSolar has achieved a major milestone with its hybrid technology HyperSolar, a company that specializes in combining hydrogen fuel cells with solar energy, has reached a significant milestone in terms of hydrogen production. The company harnesses the power of the sun in order to generate the electrical power needed to produce hydrogen fuel. This is […]
Rice University researchers have demonstrated an efficient new way to capture the energy from sunlight and convert it into clean, renewable energy by splitting water molecules. The technology, which is described online in the American Chemical Society journal Nano Letters, relies on a configuration of light-activated gold nanoparticles that harvest sunlight and transfer solar energy […]
NREL researchers Myles Steiner (left), John Turner, Todd Deutsch and James Young stand in front of an atmospheric pressure MDCVD reactor used to grow crystalline semiconductor structures. They are co-authors of the paper “Direct Solar-to-Hydrogen Conversion via Inverted Metamorphic Multijunction Semiconductor Architectures” published in Nature Energy. Photo by Dennis Schroeder. Scientists at the U.S. […]
Photo shows a lead sulfide quantum dot solar cell. A lead sulfide quantum dot solar cell developed by researchers at NREL. Photo by Dennis Schroeder.
Scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) have developed a proof-of-principle photo-electro-chemical cell capable of capturing excess photon energy normally lost to generating heat. Using quantum […]
How can we store solar energy for period when the sun doesn’t shine?
One solution is to convert it into hydrogen through water electrolysis. The idea is to use the electrical current produced by a solar panel to ‘split’ water molecules into hydrogen and oxygen. Clean hydrogen can then be stored away for future use to produce electricity on demand, or even as a fuel.
But this is where things get complicated. Even though different hydrogen-production technologies have given us promising results in the lab, they are still too unstable or expensive and need to be further developed to use on a commercial and large scale.
The approach taken by EPFL and CSEM researchers is to combine components that have already proven effective in industry in order to develop a robust and effective system. Their prototype is made up of three interconnected, new-generation, crystalline silicon solar cells attached to an electrolysis system that does not rely on rare metals.
The device is able to convert solar energy into hydrogen at a rate of 14.2%, and has already been run for more than 100 hours straight under test conditions. In terms of performance, this is a world record for silicon solar cells and for hydrogen production without using rare metals. It also offers a high level of stability.
The device is able to convert solar energy into hydrogen at a rate of 14.2 percent, and has already been run for more than 100 hours straight. (Image: Infini Lab / EPFL)
Enough to power a fuel cell car over 10,000km every year
An Effective and Low-Cost Solution for Storing Solar Energy
The method, which surpasses previous efforts in terms of stability, performance, lifespan and cost efficiency, is published in the Journal of The Electrochemical Society (“Solar-to-Hydrogen Production at 14.2% Efficiency with Silicon Photovoltaics and Earth-Abundant Electrocatalysts”). “A 12-14 m2 system installed in Switzerland would allow the generation and storage of enough hydrogen to power a fuel cell car over 10,000 km every year”, says Christophe Ballif, who co-authored the paper.
High voltage cells have an edge
The key here is making the most of existing components, and using a ‘hybrid’ type of crystalline-silicon solar cell based on hetero-junction technology. The researchers’ sandwich structure – using layers of crystalline silicon and amorphous silicon – allows for higher voltages. And this means that just three of these cells, interconnected, can already generate an almost ideal voltage for electrolysis to occur. The electro-chemical part of the process requires a catalyst made from nickel, which is widely available.
“With conventional crystalline silicon cells, we would have to link up four cells to get the same voltage,” says co-author Miguel Modestino at EPFL.”So that’s the strength of this method.”
A stable and economically viable method
The new system is unique when it comes to cost, performance and lifespan. “We wanted to develop a high performance system that can work under current conditions,” says Jan-Willem Schüttauf, a researcher at CSEM and co-author of the paper. “The hetero-junction cells that we use belong to the family of crystalline silicon cells, which alone account for about 90% of the solar panel market. It is a well-known and robust technology whose lifespan exceeds 25 years.
And it also happens to cover the south side of the CSEM building in Neuchâtel.”
The researchers used standard hetero-junction cells to prove the concept; by using the best cells of that type, they would expect to achieve a performance above 16%.
Source: Ecole Polytechnique Fédérale de Lausanne
Researchers at Rice University are on to a relatively simple, low-cost way to pry hydrogen loose from water, using the sun as an energy source. The new system involves channeling high-energy “hot” electrons into a useful purpose before they get a chance to cool down. If the research progresses, that’s great news for the hydrogen fuel cell electric vehicle market, which has been growing in some niche sectors but stumbling over the cost barrier when it comes to passenger cars and buses.
If you are new to the topic, the high energy density of hydrogen makes it ideal for fuel cell electric vehicles, but manufacturing hydrogen is an energy-intensive process that currently depends on fossil natural gas as a source.
The emergence of solar water-splitters could solve both of those problems together, by using renewable energy to split water into hydrogen and oxygen. Wind, hydropower, and tidal energy are also possible “clean” power sources for manufacturing hydrogen from water. Potable water resources aren’t necessarily compromised, as emerging technology works onless-than-clean water, including municipal wastewater.
The new Rice University hydrogen system resolves some of the problems besetting conventional water-splitting attempts.
The research team developed a three-layer material, which starts with a thin sheet of aluminum coated with a nanoscale, transparent layer of nickel oxide. The topmost layer is a smattering of ultra-tiny gold disks ranging from 10 to 30 nanometers in diameter.
The material can collect sunlight both directly and as a reflection from the aluminum layer. In either case, the gold nanoparticles convert light into high energy “hot” electrons (more on that later). Low-energy electron “holes” are attracted to the aluminum layer and the nickel oxide layer lets them pass through, while making the hot electrons stay behind on the gold discs.
So far, the researcher team has determined that the photocurrent generated by the new material is potentially sufficient for water-splitting, and is “on par” with more complex, costly systems.
The next step is to take direct measurements of the hydrogen and oxygen gases produced by the reaction.
Because they are very energetic, “hot” electrons can be very useful in driving chemical reactions. The problem is that they decay rapidly. To get a handle on just how rapidly, the Rice research team suggests that you consider this:
…most of the energy losses in today’s best photovoltaic solar panels are the result of hot electrons that cool within a few trillionths of a second and release their energy as wasted heat.
If you can grab hot electrons and put them to use before they cool down, the payoff is a huge improvement in solar conversion efficiency.
For a solution, the Rice team looked to the university’s previous work in plasmons. Plasmons refer to electrons that travel across metal surfaces like waves. As with hot electrons, plasmons have an extremely short lifespan, but the magic happens when you put the two together.
Hot electrons and their corresponding holes are caused by a plasmonic “jolt” of energy. The challenge is to keep the two states separated, so the hot electron can’t revert to its low energy state.
The conventional way to do this is by pushing the hot electrons over an energy barrier. It’s an inefficient approach but it is widely used because it is based on familiar technology. The Rice team came at the problem from the opposite angle:
We took an unconventional approach: Rather than driving off the hot electrons, we designed a system to carry away the electron holes. In effect, our setup acts like a sieve or a membrane. The holes can pass through, but the hot electrons cannot, so they are left available on the surface of the plasmonic nanoparticles.
When Tesla Motors cofounder Elon Musk famously quipped that fuel cell vehicles (FCEVs) are BS, at least one FCEV maker took him at his word, pointing out that you could potentially run a FCEV on hydrogen sourced from cow manure.
We’re not quite there yet — fossil natural gas is still the primary source of hydrogen for fuel cells for monetary reasons — but in the meantime, FCEVs are making inroads in a number of important niche markets, particularly logistics.
In Germany fuel cells with Professor Dr. Gunther Kolb, head of the Department of Decentralized and Mobile Energy Technology at Fraunhofer ICT-IMM, showcased one recent marketing fail, Dr. Kolb affirmed that fuel cell technology is “absolutely competitive” with battery technology for stationary storage.
In Switzerland the country’s solar hydrogen and power-t0-gas research at École polytechnique fédérale de Lausanne, and the deployment of hydrogen in homes and vehicles at Empa, the Swiss federal Materials & Technology institute — researchers made it clear that Switzerland is all over hydrogen as a long-term energy storage solution for winter, with is the “dry” season for the country’s massive hydropower systems.
Groundbreaking research at Griffith University is leading the way in clean energy, with the use of carbon as a way to deliver energy using hydrogen.
Professor Xiangdong Yao and his team from Griffith’s Queensland Micro- and Nanotechnology Centre have successfully managed to use the element to produce hydrogen from water as a replacement for the much more costly platinum.
“Hydrogen production through an electrochemical process is at the heart of key renewable energy technologies including water splitting and hydrogen fuel cells,” says Professor Yao.
“Despite tremendous efforts, exploring cheap, efficient and durable electrocatalysts for hydrogen evolution still remains a great challenge.
“Platinum is the most active and stable electrocatalyst for this purpose, however its low abundance and consequent high cost severely limits its large-scale commercial applications.
“We have now developed this carbon-based catalyst, which only contains a very small amount of nickel and can completely replace the platinum for efficient and cost-effective hydrogen production from water.
“In our research, we synthesize a nickel-carbon-based catalyst, from carbonization of metal-organic frameworks, to replace currently best-known platinum-based materials for electrocatalytic hydrogen evolution.
“This nickel-carbon-based catalyst can be activated to obtain isolated nickel atoms on the graphitic carbon support when applying electrochemical potential, exhibiting highly efficient hydrogen evolution performance and impressive durability.”
Proponents of a hydrogen economy advocate hydrogen as a potential fuel for motive power including cars and boats and on-board auxiliary power, stationary power generation (e.g., for the energy needs of buildings), and as an energy storage medium (e.g., for interconversion from excess electric power generated off-peak).
Professor Yao says that this work may enable new opportunities for designing and tuning properties of electrocatalysts at atomic scale for large-scale water electrolysis.
Splitting water is a two-step process, and in a new study, researchers have performed one of these steps (reduction) with 100% efficiency. The results shatter the previous record of 60% for hydrogen production with visible light, and emphasize that future research should focus on the other step (oxidation) in order to realize practical overall water splitting. The main application of splitting water into its components of oxygen and hydrogen is that the hydrogen can then be used to deliver energy to fuel cells for powering vehicles and electronic devices.
The researchers, Philip Kalisman, Yifat Nakibli, and Lilac Amirav at the Technion-Israel Institute of Technology in Haifa, Israel, have published a paper on the perfect efficiency for the water reduction half-reaction in a recent issue of Nano Letters.
“I strongly believe that the search for clean and renewable energy sources is crucial,” Amirav toldPhys.org. “With the looming energy crisis on one hand, and environmental aspects, mainly global warming, on the other, I think this is our duty to try and amend the problem for the next generation.
“Our work shows that it is possible to obtain a perfect 100% photon-to-hydrogen production efficiency, under visible light illumination, for the photocatalytic water splitting reduction half-reaction. These results shatter the previous benchmarks for all systems, and leave little to no room for improvement for this particular half-reaction. With a stable system and a turnover frequency of 360,000 moles of hydrogen per hour per mole of catalyst, the potential here is real.”
When an H2O molecule splits apart, the three atoms don’t simply separate from each other. The full reaction requires two H2O molecules to begin with, and then proceeds by two separate half-reactions. In the oxidation half-reaction, four individual hydrogen atoms are produced along with an O2 molecule (which is discarded). In the reduction half-reaction, the four hydrogen atoms are paired up into two H2 molecules by adding electrons, which produces the useful form of hydrogen: H2 gas.
In the new study, the researchers showed that the reduction half-reaction can be achieved with perfect efficiency on specially designed 50-nm-long nanorods placed in a water-based solution under visible light illumination. The light supplies the energy required to drive the reaction forward, with the nanorods acting as photocatalysts by absorbing the photons and in turn releasing electrons needed for the reaction.
The 100% efficiency refers to the photon-to-hydrogen conversion efficiency, and it means that virtually all of the photons that reach the photocatalyst generate an electron, and every two electrons produce one H2 molecule. At 100% yield, the half-reaction produces about 100 H2 molecules per second (or one every 10 milliseconds) on each nanorod, and a typical sample contains about 600 trillion nanorods.
One of the keys to achieving the perfect efficiency was identifying the bottleneck of the process, which was the need to quickly separate the electrons and holes (the vacant places in the semiconductor left after the electrons leave), and remove the holes from the photocatalyst. To improve the charge separation, the researchers redesigned the nanorods to have just one platinum catalyst instead of two. The researchers found that the efficiency increased from 58.5% with two platinum catalysts to 100% with only one.
Going forward, the researchers plan to further improve the system. The current demonstration requires a very high pH, but such strong basic conditions are not always ideal in practice. Another concern is that the cadmium sulfide (CdS) used in the nanorod becomes corroded under prolonged light exposure in pure water. The researchers are already addressing these challenges with the goal to realize practical solar-to-fuel technology in the future.
“We hope to implement our design rules, experience and accumulated insights for the construction of a system capable of overall water splitting and genuine solar-to-fuel energy conversion,” Amirav said.
“The photocatalytic hydrogen generation presented here is not yet genuine solar-to-fuel energy conversion, as hole scavengers are still required. CdS is unfortunately not suitable for overall water splitting since prolonged irradiation of its suspensions leads to photocorrosion. We have recently demonstrated some breakthrough on this direction as well. The addition of a second co-catalyst, such as IrO2 or Ru, which can scavenge the holes from the semiconductor and mediate their transfer to water, affords CdS-based structures the desired photochemical stability. I believe this is an important milestone.”
More information: Philip Kalisman, et al. “Perfect Photon-to-Hydrogen Conversion Efficiency.” Nano Letters. DOI: 10.1021/acs.nanolett.5b04813
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