Lehigh University engineers have utilized a single enzyme biomineralization process to create a catalyst that uses the energy of captured sunlight to split water molecules to produce hydrogen. The synthesis process is performed at room temperature and under ambient pressure, overcoming the sustainability and scalability challenges of previously reported methods.

Solar-driven water splitting is a promising route towards a renewable energy-based economy. The generated hydrogen could serve as both a transportation fuel and a critical chemical feedstock for fertilizer and chemical production. Both of these sectors currently contribute a large fraction of total greenhouse gas emissions.

Catalyst splits water in sunlight with an enzyme made with a biomineralization process. Image Credit: Lehigh University. Click image for the largest view.

One of the challenges to realizing the promise of solar-driven energy production is that, while the required water is an abundant resource, previously-explored methods utilize complex routes that require environmentally-damaging solvents and massive amounts of energy to produce at large scale. The expense and harm to the environment have made these methods unworkable as a long-term solution.

Now a team of engineers at Lehigh University have harnessed a biomineralization approach to synthesizing both quantum confined nanoparticle metal sulfide particles and the supporting reduced graphene oxide material to create a photocatalyst that splits water to form hydrogen.

The team reported their results in an article entitled: “Enzymatic synthesis of supported CdS quantum dot/reduced graphene oxide photocatalysts” featured on the cover of the August 7th issue of Green Chemistry, a journal of the Royal Society of Chemistry.

The paper’s authors include: Steven McIntosh, Professor in Lehigh’s Department of Chemical and Biomolecular Engineering, along with Leah C. Spangler, former Ph.D. student and John D. Sakizadeh, current Ph.D. student; as well, as Christopher J. Kiely, Harold B. Chambers Senior Professor in Lehigh’s Department of Materials Science and Engineering and Joseph P. Cline, a Ph.D. student working with Kiely.

McIntosh, who is also Associate Director of Lehigh’s Institute for Functional Materials and Devices said. “Our water-based process represents a scalable green route for the production of this promising photocatalyst technology.”

Over the past several years, McIntosh’s group has developed a single enzyme approach for biomineralization – the process by which living organisms produce minerals of size-controlled, quantum confined metal sulfide nanocrystals. In a previous collaboration with Kiely, the lab successfully demonstrated the first precisely controlled, biological way to manufacture quantum dots. Their one-step method began with engineered bacterial cells in a simple, aqueous solution and ended with functional semiconducting nanoparticles, all without resorting to high temperatures and toxic chemicals. The method was featured in a New York Times article: “How a Mysterious Bacteria Almost Gave You a Better TV.”

Spangler, lead author and currently a Postdoctoral Research Fellow at Princeton University said, “Other groups have experimented with biomineralization for chemical synthesis of nanomaterials. The challenge has been achieving control over the properties of the materials such as particle size and crystallinity so that the resulting material can be used in energy applications.”

McIntosh described how Spangler was able to tune the group’s established biomineralization process to not only synthesize the cadmium sulfide nanoparticles but also to reduce graphene oxide to the more conductive reduced graphene oxide form.

“She was then able to bind the two components together to create a more efficient photocatalyst consisting of the nanoparticles supported on the reduced graphene oxide. Thus her hard work and resulting discovery enabled both critical components for the photocatalyst to be synthesized in a green manner,” explained McIntosh.

The team’s work demonstrates the utility of biomineralization to realize benign synthesis of functional materials for use in the energy sector.

Kiely added, “Industry may consider implementation of such novel synthesis routes at scale. Other scientists may also be able to utilize the concepts in this work to create other materials of critical technological importance.”

McIntosh emphasized the potential of this promising new method as “a green route, to a green energy source, using abundant resources. It is critical to recognize that any practical solution to the greening of our energy sector will have to be implemented at enormous scale to have any substantial impact.”

While the motivator in this research is the green energy field, this work likely has important potential in other fields as well. Each new catalyst, catalyst formation process and catalyst function development has large effects and we’re only just seeing the rush of improvements come out of labs. As these ideas blossom others will follow and one has to watch in wonder where all of this can lead.

Stanford University has built a new battery made from affordable and durable materials that generates energy from places where salt and fresh waters merge together. The technology could make coastal wastewater treatment plants energy-independent and carbon neutral.

Salt has power potential. It might sound like alchemy, but the energy in places where salty ocean water and freshwater mingle could provide a massive source of renewable power. Stanford researchers have developed an affordable, durable technology that could harness this so-called ‘blue energy’.

The team’s paper published in American Chemical Society’s ACS Omega, describes the battery and suggests using it to make coastal wastewater treatment plants energy-independent.

Study coauthor Kristian Dubrawski, a postdoctoral scholar in civil and environmental engineering at Stanford said, “Blue energy is an immense and untapped source of renewable energy. Our battery is a major step toward practically capturing that energy without membranes, moving parts or energy input.”

For a full description click the study link above. Image Credit: Stanford University. Click image for the largest view.

Dubrawski works in the lab of study co-author Craig Criddle, a professor of civil and environmental engineering known for interdisciplinary field projects of energy-efficient technologies. The idea of developing a battery that taps into salt gradients originated with study coauthors Yi Cui, a professor of materials science and engineering, and Mauro Pasta, a postdoctoral scholar in materials science and engineering at the time of the research. Applying that concept to coastal wastewater treatment plants was Criddle’s twist, born of his long experience developing technologies for wastewater treatment.

The researchers tested a prototype of the battery, monitoring its energy production while flushing it with alternating hourly exchanges of wastewater effluent from the Palo Alto Regional Water Quality Control Plant and seawater collected nearby from Half Moon Bay. Over 180 cycles, battery materials maintained 97 percent effectiveness in capturing the salinity gradient energy.

The technology could work any place where fresh and saltwater intermix, but wastewater treatment plants offer a particularly valuable case study. Wastewater treatment is energy-intensive, accounting for about three percent of the total U.S. electrical load. The process – essential to community health – is also vulnerable to power grid shutdowns. Making wastewater treatment plants energy independent would not only cut electricity use and emissions but also make them immune to blackouts – a major advantage in places such as California, where recent wildfires have led to large-scale outages.

Every cubic meter of freshwater that mixes with seawater produces about .65 kilowatt-hours of energy – enough to power the average American house for about 30 minutes. Globally, the theoretically recoverable energy from coastal wastewater treatment plants is about 18 gigawatts – enough to power more than 1,700 homes for a year.

The Stanford group’s battery isn’t the first technology to succeed in capturing blue energy, but it’s the first to use battery electrochemistry instead of pressure or membranes. If it works at scale, the technology would offer a more simple, robust and cost-effective solution.

The process first releases sodium and chloride ions from the battery electrodes into the solution, making the current flow from one electrode to the other. Then, a rapid exchange of wastewater effluent with seawater leads the electrode to reincorporate sodium and chloride ions and reverse the current flow. Energy is recovered during both the freshwater and seawater flushes, with no upfront energy investment and no need for charging. This means that the battery is constantly discharging and recharging without needing any input of supporting energy.

While lab tests showed power output is still low per electrode area, the battery’s scale-up potential is considered more feasible than previous technologies due to its small footprint, simplicity, constant energy creation and lack of membranes or instruments to control charge and voltage. The electrodes are made with Prussian Blue, a material widely used as a pigment and medicine, that costs less than $1 a kilogram, and polypyrrole, a material used experimentally in batteries and other devices, which sells for less than $3 a kilogram in bulk.

There’s also little need for backup batteries, as the materials are relatively robust, a polyvinyl alcohol and sulfosuccinic acid coating protects the electrodes from corrosion and there are no moving parts involved. If scaled up, the technology could provide adequate voltage and current for any coastal treatment plant. Surplus power production could even be diverted to a nearby industrial operation, such as a desalination plant.

Dubrawski said, “It is a scientifically elegant solution to a complex problem, It needs to be tested at scale, and it doesn’t address the challenge of tapping blue energy at the global scale – rivers running into the ocean – but it is a good starting point that could spur these advances.”

Dubrawski summed it up well enough. It must be better technology than one might initially think. Waste treatment involves lots of motor driven pumps so the idea that the merging of sea water and the fresh effluent water could power the plant seems quite impressive.

ETH Zurich scientists have developed a new catalyst that converts CO2 and hydrogen into methanol. The new catalyst offers realistic market potential that make for the sustainable production of fuels and chemicals from recycled CO2

The global economy still relies on the fossil carbon sources of petroleum, natural gas and coal, not just to produce fuel, but also as a raw material used by the chemical industry to manufacture plastics and countless other chemical compounds. Although efforts have been made for some time to find ways of manufacturing liquid fuels and chemical products from alternative, sustainable resources, these have not yet progressed beyond niche applications.

The scientists at ETH Zurich, now teamed up with the French oil and gas company Total to develop a new technology, efficiently converts CO2 and hydrogen directly into methanol. Methanol is regarded as a commodity or bulk chemical. It is possible to convert it into fuels and a wide variety of chemical products, including those that today are mainly based on fossil resources. Moreover, methanol itself has the potential to be utilized as a fuel source, in methanol fuel cells, for example.

The team’s study paper has been published in Nature Communications.

The core of the new approach is a chemical catalyst based on indium oxide, which was developed by Javier Pérez-Ramírez, Professor of Catalysis Engineering at ETH Zurich, and his team. Just a few years ago, the team successfully demonstrated in experiments that indium oxide was capable of catalyzing the necessary chemical reaction. Even at the time, it was encouraging that doing so generated virtually only methanol and almost no by-products other than water. The catalyst also proved to be highly stable. However, indium oxide was not sufficiently active as a catalyst; the large quantities needed prevent it from being a commercially viable option.

Now the team of scientists have succeeded in boosting the activity of the catalyst significantly, without affecting its selectivity or stability. They achieved this by treating the indium oxide with a small quantity of palladium.

“More specifically, we insert some single palladium atoms into the crystal lattice structure of the indium oxide, which anchor further palladium atoms to its surface, generating tiny clusters that are essential for the remarkable performance,” explained Cecilia Mondelli, a lecturer in Pérez-Ramírez’s group. Pérez-Ramírez pointed out that, with the aid of advanced analytical and theoretical methods, catalysis may now be considered nanotechnology, and in fact, the project clearly shows this to be the case.

“Nowadays, deriving methanol on an industrial scale is done exclusively from fossil fuels, with a correspondingly high carbon footprint,” Pérez-Ramírez said. “Our technology uses CO2 to produce methanol.” The CO2 may be extracted from the atmosphere or – more simply and efficiently – from the exhaust discharged by combustion power plants. Even if fuels are synthesized from the methanol and subsequently combusted, the CO2 is recycled and thus the carbon cycle is closed.

Producing the second raw material, hydrogen, requires electricity. However, the scientists point out that if this electricity comes from renewable sources such as wind, solar or hydropower energy, it can be used to make sustainable methanol and thus sustainable chemicals and fuels.

Compared to other methods that are currently being applied to produce green fuels, Pérez-Ramírez continued, this technology has the great advantage that it is almost ready for the market. ETH Zurich and Total have jointly filed a patent for the technology. Total now plans to scale up the approach and potentially implement the technology in a demonstration unit over the next few years.

Methanol is a pretty good fuel, it burns clean and has a native high octane. The downside is the energy content is lower than gasoline or diesel. That means larger tanks.

On the other hand, in a fuel cell methanol is a very good fuel indeed. A stabile liquid it stores without pressurization. This idea is a very good one, recycle CO2 and add hydrogen to the fuel supply. Lets hope this technology takes off.

Uppsala University researchers have successfully produced microorganisms that can efficiently produce the alcohol butanol using carbon dioxide and solar energy. The researchers press release is optimistic that we will be able to replace fossil fuels with a carbon-neutral product created from solar energy, carbon dioxide and water.

The researchers have published their study in the scientific journal Energy & Environmental Science.

Pia Lindberg, Senior Lecturer at the Department of Chemistry Ångström Laboratory, Uppsala University explained they have systematically designed and created a series of modified cyanobacteria that gradually produced increasing quantities of butanol in direct processes. When the best cells are used in long-term laboratory experiments, they see levels of production that exceed levels that have been reported in existing articles. Most impressive, it is comparable with indirect processes where bacteria are fed with sugar.

See the study linked above for more information. Image Credit: Department of Chemistry Ångström Laboratory, Uppsala University. Click image for the largest view.

The knowledge and ability to modify cyanobacteria so they can produce a variety of chemicals from carbon dioxide and solar energy is emerging in parallel with advances in technology, synthetic biology, genetically changing them. Through a combination of technical development, systematic methods and the discovery that as more product removed from the cyanobacteria, the more butanol is formed, the study shows the way forward for realizing the concept.

The Uppsala team already knew it is possible to produce butanol using this process (proof-of-concept). What researchers have now been able to show is that it is possible to achieve significantly higher production, so high that it becomes possible to use in production. In practical terms, butanol can be used in the automotive industry as both an environmentally friendly vehicle fuel – fourth generation biofuel – and as an environmentally friendly component of rubber for tires. In both cases, fossil fuels are replaced by a carbon-neutral product created from solar energy, carbon dioxide and water.

Even larger industries, in all trades, that currently produce high greenhouse gas emissions from carbon dioxide will be able to use the process with cyanobacteria to bind carbon dioxide recycling it and consequently significantly reduce their emissions.

Peter Lindblad, Professor at the Department of Chemistry Ångström Laboratory at Uppsala University who is leading the project explained microscopic cyanobacteria are the most efficient photosynthetic organisms on earth. In this study, they utilized their ability to efficiently capture the sun’s energy and bind to carbon dioxide in the air, alongside with all the tools science has to modify cyanobacteria to produce desirable products. The results show that a direct production of carbon-neutral chemicals and fuels from solar energy will be a possibility in the future,

The research at Uppsala University is part of the larger EU Photofuel project being coordinated by vehicle manufacturer VW whose aim is to develop the next generation of techniques for sustainable manufacture of alternative fuels in the transport sector.

Butanol has been missing in action for years. As a near drop in replacement for gasoline with comparable energy content the butanol market would be an shoe in. The one problem has been separating out the butanol before it poisons the feedstock.

But now, with only carbon dioxide as a feedstock, that problem may be bypassed. We will see, and will be keeping a eye out for what progress this team makes.

Researchers at Kyushu University in Japan can now provide new insights into the reactions occurring in solid-oxide fuel cells. By using realistic simulations with atomic-scale models of the electrode active site based on microscope observations, instead of the simplified and idealized atomic structures employed in previous studies, a better understanding of how the structures in the cells affect the reactions could give clues on ways to improve performance and durability in future devices.

The initial positions of the atoms in this computer model of a solid-oxide fuel cell were based on observations of the actual atomic configuration using electron microscopy. Simulations using this model revealed a previously unreported reaction (red path) in which an oxygen molecule from the yttria-stabilized zirconia layer (layer of red and light blue balls) moves through the bulk nickel layer (dark blue balls) before forming OH on the nickel surface. Image Credit: Kyushu University. Click image for the largest view.

Extremely promising for the clean and efficient electricity generation, solid-oxide fuel cells produce electricity through the electrochemical reaction of a fuel with air, and they have already begun to find their way into homes and office buildings throughout Japan.

In a typical fuel cell, oxygen molecules on one side of the fuel cell first receive electrons and break up into oxide ions. The oxide ions then travel through an electrolyte to the other side of the device, where they react with the fuel and release their extra electrons. These electrons flow through outside wires back to the starting side, thereby completing the circuit and powering whatever is connected to the wires.

Although this overall reaction is well known and relatively simple, the reaction step limiting the overall rate of the process remains controversial because the complicated structures of the electrodes – which are generally porous materials as opposed to simple, flat surfaces – hinder investigation of the phenomena at the atomic level.

Since detailed knowledge about the reactions occurring in the devices is vital for further improving the performance and durability of fuel cells, the challenge has been to understand how the microscopic structures – down to the alignment of the atoms at the different interfaces – affect the reactions.

Michihisa Koyama, the head of the group that led the research at Kyushu University’s INAMORI Frontier Research Center explained, “Computer simulations have played a powerful role in predicting and understanding reactions that we cannot easily observe on the atomic or molecular scale. However, most studies have assumed simplified structures to reduce the computational cost, and these systems cannot reproduce the complex structures and behavior occurring in the real world.”

Koyama’s group aimed to overcome these shortcomings by applying simulations with refined parameters to realistic models of the key interfaces based on microscopic observations of the actual positions of the atoms at the active site of the electrode.

The group’s research paper has been published in journal Communications Chemistry.

Leveraging the strength of Kyushu University’s Ultramicroscopy Research Center, the researchers carefully observed the atomic structure of thin slices of the fuel cells using atomic-resolution electron microscopy. Based on these observations, the researchers then reconstructed computer models with the same atomic structures for two representative arrangements that they observed.

Reactions between hydrogen and oxygen in these virtual fuel cells were then simulated with a method called Reactive Force Field Molecular Dynamics, which uses a set of parameters to approximate how atoms will interact – and even chemically react – with each other, without going into the full complexity of rigorous quantum chemical calculations. In this case, the researchers employed an improved set of parameters developed in collaboration with Yoshitaka Umeno’s group at the University of Tokyo.

Looking at the outcome of multiple runs of the simulations on the different model systems, the researchers found that the desired reactions were more likely to occur in the layers with a smaller pore size.

Koyama’s group also identified a new reaction pathway in which oxygen migrates through the bulk layers in a way that could potentially degrade performance and durability. Thus, strategies to avoid this potential reaction route should be considered as researchers work to design improved fuel cells.

Koyama quoted in the press release said, “These are the kinds of insights that we could only get by looking at real-world systems. In the future, I expect to see more people using real-world atomic structures recreated from microscope observations for the basis of simulations to understand phenomena that we cannot easily measure and observe in the laboratory.”

While fuel cells are already a leading means to efficiently produce power they remain somewhat costly and experience short life spans compared to simply using grid power. But the potential is great and this research is going to help fuel cells gain much more longevity at lower cost as it saturates into the market. This is good useful work that deserves notice and acknowledgment for a worthwhile contribution. Your humble writer is sure there is more to come about this.


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