Nanomaterials that ‘self-assemble’ offer pathway to a more efficient, affordable harnessing of Solar Power


more efficient solar selfassembli
In this illustration, DPP and rylene dye molecules come together to create a self-assembled superstructure. Electrons within the structure absorb and become excited by light photons, and then couple with neighboring electrons to share …more

Solar rays are a plentiful, clean source of energy that is becoming increasingly important as the world works to shift away from power sources that contribute to global warming.

But current methods of harvesting solar charges are in large expensive and inefficient—with a theoretical efficiency limit of 33 percent. New nanomaterials developed by researchers at the Advanced Science Research Center (ASRC) at The Graduate Center of The City University of New York (CUNY) could provide a pathway to more efficient and potentially affordable harvesting of solar energy.

The materials, created by scientists with the ASRC’s Nanoscience Initiative, use a process called singlet fission to produce and extend the life of harvestable light-generated electrons. The discovery is described in a newly published paper in the Journal of Physical Chemistry. Early research suggests these materials could create more usable charges and increase the theoretical efficiency of  up to 44 percent.

“We modified some of the molecules in commonly used industrial dyes to create self-assembling materials that facilitate a greater yield of harvestable electrons and extend the electrons’ xcited-state lifetimes, giving us more time to collect them in a solar cell,” said Andrew Levine, lead author of the paper and a Ph.D. student at The Graduate Center.

The self-assembly process, Levine explained, causes the  to stack in a particular way. This stacking allows dyes that have absorbed solar photons to couple and share energy with —or “excite”—neighboring dyes. The electrons in these dyes then decouple so that they can be collected as harvestable solar energy.

Methodology and Findings

To develop the materials, researchers combined various versions of two frequently used industrial dyes—diketopyrrolopyrrole (DPP) and rylene. This resulted in the formation of six self-assembling superstructures, which scientists investigated using electron microscopy and advanced spectroscopy. They found that each combination had subtle differences in geometry that affected the dyes’ excited states, the occurrence of singlet fission, and the yield and lifetime of harvestable electrons. Significance

“This work provides us with a library of nanomaterials that we can study for harvesting solar energy,” said Professor Adam Braunschweig, lead researcher on the study and an associate professor with the ASRC Nanoscience Initiative and the Chemistry Departments at Hunter College and The Graduate Center. “Our method for combining the dyes into functional materials using self-assembly means we can carefully tune their properties and increase the efficiency of the critical light-harvesting process.”

The materials’ ability to self-assemble could also shorten the time for creating commercially viable solar cells, said the researchers, and prove more affordable than current fabrication methods, which rely on the time-consuming process of molecular synthesis.

The research team’s next challenge is to develop a method of harvesting the solar charges created by their new nanomaterials. Currently, they are working to design a rylene molecule that can accept the electron from the DPP molecule after the singlet fission process. If successful, these  would both initiate the singlet fission process and facilitate charge-transfer into a solar cell.

 Explore further: Pathway opens to minimize waste in solar energy capture

More information: Andrew M. Levine et al, Singlet Fission in Combinatorial Diketopyrrolopyrrole–Rylene Supramolecular Films, The Journal of Physical Chemistry C (2019). DOI: 10.1021/acs.jpcc.8b09593

 

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Tesla is reportedly in talks with China’s Lishen over Shanghai battery contract


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  • Tesla has signed a preliminary agreement with China’s Tianjin Lishen to supply batteries for its new Shanghai car factory, as it aims to cut its reliance on Japan’s Panasonic, two sources with direct knowledge of the matter said.
  • The companies had yet to reach a decision on how large an order the U.S. electric car company would place, and Lishen was still working out what battery cell size Tesla would require, one of the sources said.

 

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Tesla CEO Elon Musk attends the Tesla Shanghai Gigafactory groundbreaking ceremony in Shanghai, China, January 7, 2019.

Tesla has signed a preliminary agreement with China’s Tianjin Lishen to supply batteries for its new Shanghai car factory, as it aims to cut its reliance on Japan’s Panasonic, two sources with direct knowledge of the matter said.

The companies had yet to reach a decision on how large an order the U.S. electric car company would place, and Lishen was still working out what battery cell size Tesla would require, one of the sources said.

While Panasonic is currently Tesla’s exclusive battery cell supplier, Tesla Chief Executive Elon Musk said in November the U.S. company would manufacture all its battery modules and packs at the Shanghai factory and planned to diversify its sources.

“Cell production will be sourced locally, most likely from several companies (incl Pana), in order to meet demand in a timely manner,” Musk said in a tweet in November.

Other battery makers in the running for contracts could include Contemporary Amperex Technology and LG Chem.

Tesla broke ground on the $2 billion so-called Gigafactory, its first in China, earlier this month and plans to begin making Model 3 electric vehicles (EV) there by the end of the year.

Story from Reuters News Service

Toyota and Panasonic are teaming up in massive EV battery cell venture, report says


Panasonic, Tesla’s battery cell partner, is reportedly teaming up with Toyota to create an important electric vehicle battery cell venture in China and Japan.

According to a report from Japan’s Nikkei, the two Japanese companies would create a new joint-venture that would result in Panasonic producing a large number of cells for the automaker”

“The venture, in which Toyota is to hold a 51% stake with Panasonic owning the rest, will be announced as soon as this week. Panasonic will shift five automotive battery production facilities in Japan and China to the new company, though the U.S. plant it operates under a partnership with American automaker Tesla will not be included.”

For Panasonic, it would represent shifting an important part of its battery cell production capacity to Toyota’s electric vehicle programs.

Read More: Toyota andPanasonic Explore ‘Prismatic’ Batteries Together

Toyota has fallen behind when it comes to all-electric vehicles as it preferred to focus on fuel cell cars for years.

Lately, it is tentatively making moves in the space since announcing an expansion of its electric car plans last year with 10 upcoming new BEVs.

The first one is supposed to launch next year and it also happens to be when this new venture with Panasonic is supposed to go into operation, according to Nikkei.

The joint-venture would not only supply batteries to Toyota vehicles but also other partners like Mazda and Subaru.

Again according to the report, it will also involve the production of next-generation battery cells, including solid-state batteries.

Just over a year ago, the two companies announced that they were exploring the possibility to cooperate on batteries.

Electrek’s Take

I’ve been saying it forever: if you want to see how serious an automaker is about electric vehicles, you need to look at what they are doing to secure battery cell supply.

Until now, I would have never said that Toyota was serious about EVs, but it could be the case if the report turns out to be true.

Interestingly, the deal appears to be reminiscent of Tesla’s battery partnership with Panasonic, but we would need more details to confirm that.

Either way, this could be very important news for the over industry. We will keep an eye out for more information.

Article by Fred Lambert

Fred is the Editor in Chief and Main Writer at Electrek.

Water-based fuel cell converts carbon emissions to electricity


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.”

Rutgers University – Alzheimer’s may be linked to defective brain cells spreading disease


Rutgers scientists say neurodegenerative diseases like Alzheimer’s and Parkinson’s may be linked to defective brain cells disposing toxic proteins that make neighboring cells sick

In a study published in Nature, Monica Driscoll, distinguished professor of molecular biology and biochemistry, School of Arts and Sciences, and her team, found that while healthy neurons should be able to sort out and and rid brain cells of toxic proteins and damaged cell structures without causing problems, laboratory findings indicate that it does not always occur.

These findings, Driscoll said, could have major implications for neurological disease in humans and possibly be the way that disease can spread in the brain.

“Normally the process of throwing out this trash would be a good thing,” said Driscoll. “But we think with neurodegenerative diseases like Alzheimer’s and Parkinson’s there might be a mismanagement of this very important process that is supposed to protect neurons but, instead, is doing harm to neighbor cells.”

Driscoll said scientists have understood how the process of eliminating toxic cellular substances works internally within the cell, comparing it to a garbage disposal getting rid of waste, but they did not know how cells released the garbage externally.

“What we found out could be compared to a person collecting trash and putting it outside for garbage day,” said Driscoll. “They actively select and sort the trash from the good stuff, but if it’s not picked up, the garbage can cause real problems.”

Working with the transparent roundworm, known as the C. elegans, which are similar in molecular form, function and genetics to those of humans, Driscoll and her team discovered that the worms — which have a lifespan of about three weeks — had an external garbage removal mechanism and were disposing these toxic proteins outside the cell as well.

Ilija Melentijevic, a graduate student in Driscoll’s laboratory and the lead author of the study, realized what was occurring when he observed a small cloud-like, bright blob forming outside of the cell in some of the worms. Over two years, he counted and monitored their production and degradation in single still images until finally he caught one in mid-formation.

“They were very dynamic,” said Melentijevic, an undergraduate student at the time who spent three nights in the lab taking photos of the process viewed through a microscope every 15 minutes. “You couldn’t see them often, and when they did occur, they were gone the next day.”

Research using roundworms has provided scientists with important information on aging, which would be difficult to conduct in people and other organisms that have long life spans.

In the newly published study, the Rutgers team found that roundworms engineered to produce human disease proteins associated with Huntington’s disease and Alzheimer’s, threw out more trash consisting of these neurodegenerative toxic materials.

While neighboring cells degraded some of the material, more distant cells scavenged other portions of the diseased proteins.

“These finding are significant,” said Driscoll. The work in the little worm may open the door to much needed approaches to addressing neurodegeneration and diseases like Alzheimer’s and Parkinson’s.”

Story Source:

Materials provided by Rutgers University. Original written by Robin Lally. Note: Content may be edited for style and length.


Journal Reference:

  1. Ilija Melentijevic, Marton L. Toth, Meghan L. Arnold, Ryan J. Guasp, Girish Harinath, Ken C. Nguyen, Daniel Taub, J. Alex Parker, Christian Neri, Christopher V. Gabel, David H. Hall, Monica Driscoll. C. elegans neurons jettison protein aggregates and mitochondria under neurotoxic stress. Nature, 2017; DOI: 10.1038/nature21362

Cite This Page:

Rutgers University. “Alzheimer’s may be linked to defective brain cells spreading disease: Study finds toxic proteins doing harm to neighboring neurons.” ScienceDaily. ScienceDaily, 10 February 2017. <www.sciencedaily.com/releases/2017/02/170210131016.htm>.

Cornell University: Pore size influences nature of complex nanostructures – Materials for energy storage, biochemical sensors and electronics


The mere presence of void or empty spaces in porous two-dimensional molecules and materials leads to markedly different van der Waals interactions across a range of distances. Credit: Yan Yang and Robert DiStasio

Building at the nanoscale is not like building a house. Scientists often start with two-dimensional molecular layers and combine them to form complex three-dimensional architectures.

And instead of nails and screws, these structures are joined together by the attractive van der Waals forces that exist between objects at the nanoscale.

Van der Waals forces are critical in constructing  for energy storage, biochemical sensors and electronics, although they are weak when compared to chemical bonds. They also play a crucial role in , determining which drugs bind to the active sites in proteins.

In new research that could help inform development of new materials, Cornell chemists have found that the empty space (“pores”) present in two-dimensional molecular building blocks fundamentally changes the strength of these van der Waals forces, and can potentially alter the assembly of sophisticated nanostructures.

The findings represent an unexplored avenue toward governing the self-assembly of complex nanostructures from porous two-dimensional building blocks.

“We hope that a more complete understanding of these forces will aid in the discovery and development of novel materials with diverse functionalities, targeted properties, and potentially novel applications,” said Robert A. DiStasio Jr., assistant professor of chemistry in the College of Arts and Sciences.

In a paper titled “Influence of Pore Size on the van der Waals Interaction in Two-Dimensional Molecules and Materials,” published Jan. 14 in Physical Review Letters, DiStasio, graduate student Yan Yang and postdoctoral associate Ka Un Lao describe a series of mathematical models that address the question of how void space fundamentally affects the attractive physical forces which occur over nanoscale distances.

In three prototypical model systems, the researchers found that particular pore sizes lead to unexpected behavior in the  that govern van der Waals forces.

Further, they write, this behavior “can be tuned by varying the relative size and shape of these void spaces … [providing] new insight into the self-assembly and design of complex nanostructures.”

While strong covalent bonds are responsible for the formation of two-dimensional molecular layers, van der Waals interactions provide the main attractive  between the layers. As such, van der Waals forces are largely responsible for the self-assembly of the complex three-dimensional nanostructures that make up many of the advanced materials in use today.

The researchers demonstrated their findings with numerous two-dimensional systems, including covalent organic frameworks, which are endowed with adjustable and potentially very large pores.

“I am surprised that the complicated relationship between void space and van der Waals forces could be rationalized through such simple models,” said Yang. “In the same breath, I am really excited about our findings, as even  in the van der Waals forces can markedly impact the properties of molecules and materials.”

Explore further: Researchers refute textbook knowledge in molecular interactions

More information: Yan Yang et al, Influence of Pore Size on the van der Waals Interaction in Two-Dimensional Molecules and Materials, Physical Review Letters (2019).  DOI: 10.1103/PhysRevLett.122.026001 

Boosting lithium ion batteries capacity 10X with Tiny Silicon Particles – University of Alberta


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U of Alberta chemists Jillian Buriak, Jonathan Veinot and their team found that nano-sized silicon particles overcome a limitation of using silicon in lithium ion batteries. The discovery could lead to a new generation of batteries …more

University of Alberta chemists have taken a critical step toward creating a new generation of silicon-based lithium ion batteries with 10 times the charge capacity of current cells.

“We wanted to test how different sizes of  nanoparticles could affect fracturing inside these batteries,” said Jillian Buriak, a U of A chemist and Canada Research Chair in Nanomaterials for Energy. ua buriak tinysiliconp

Silicon shows promise for building much higher-capacity batteries because it’s abundant and can absorb much more lithium than the graphite used in current lithium ion batteries. The problem is that silicon is prone to fracturing and breaking after numerous charge-and-discharge cycles, because it expands and contracts as it absorbs and releases lithium ions.

Existing research shows that shaping silicon into nano-scale particles, wires or tubes helps prevent it from breaking. What Buriak, fellow U of A chemist Jonathan Veinot and their team wanted to know was what size these structures needed to be to maximize the benefits of silicon while minimizing the drawbacks.

The researchers examined silicon nanoparticles of four different sizes, evenly dispersed within highly conductive graphene aerogels, made of carbon with nanoscopic pores, to compensate for silicon’s low conductivity. They found that the smallest particles—just three billionths of a metre in diameter—showed the best long-term stability after many charging and discharging cycles.

“As the particles get smaller, we found they are better able to manage the strain that occurs as the silicon ‘breathes’ upon alloying and dealloying with , upon cycling,” explained Buriak.

u of alberta imagesThe research has potential applications in “anything that relies upon  using a battery,” said Veinot, who is the director of the ATUMS graduate student training program that partially supported the research.

“Imagine a car having the same size battery as a Tesla that could travel 10 times farther or you charge 10 times less frequently, or the battery is 10 times lighter.”

Veinot said the next steps are to develop a faster, less expensive way to create  to make them more accessible for industry and technology developers.

The study, “Size and Surface Effects of Silicon Nanocrystals in Graphene Aerogel Composite Anodes for Lithium Ion Batteries,” was published in Chemistry of Materials.

 Explore further: Toward cost-effective solutions for next-generation consumer electronics, electric vehicles and power grids

More information: Maryam Aghajamali et al. Size and Surface Effects of Silicon Nanocrystals in Graphene Aerogel Composite Anodes for Lithium Ion Batteries, Chemistry of Materials (2018). DOI: 10.1021/acs.chemmater.8b03198

Watch a YouTube Video about an Energy Storage Company Tenka Energy, Inc., that has developed and prototyped the NextGen of silicon-lithium-ion batteries for EV’s, Drones, Medical Sensors ….

Tenka Energy, Inc. Building Ultra-Thin Energy Dense SuperCaps and NexGen Nano-Enabled Pouch & Cylindrical Batteries – Energy Storage Made Small and POWERFUL!

via @Genesisnanotech #greatthingsfromsmallthings #energystorage

Ultra ultrasound to revolutionize Technology – From Medical Devices to Unmanned Vehicles


ultraultraso    Credit: University of Queensland

A new and extremely sensitive method of measuring ultrasound could revolutionise everything from medical devices to unmanned vehicles.

Researchers at The University of Queensland have combined modern nanofabrication and nanophotonics techniques to build the ultraprecise  sensors on a silicon chip.

Professor Warwick Bowen, from UQ’s Precision Sensing Initiative and the Australian Centre for Engineered Quantum Systems, said the development could usher in a host of exciting new technologies.

“This is a major step forward, since accurate ultrasound measurement is critical for a range of applications,” he said.

“Ultrasound is used for medical ultrasound, often to examine , as well as for  biomedical imaging to detect tumours and other anomalies.

“It’s also commonly used for spatial applications, like in the sonar imaging of underwater objects or in the navigation of unmanned aerial vehicles.

“Improving these applications requires smaller, higher precision sensors and, with this new technique, that’s exactly what we’ve been able to develop.”

The technology is so sensitive that it can hear, for the first time, the miniscule random forces from surrounding air molecules.

“We’ve developed a near perfect ultrasound detector, hitting the limits of what the technology is capable of achieving,” Professor Bowen said.

“We’re now able to measure ultrasound waves that apply tiny forces – comparable to the gravitational force on a virus – and we can do this with sensors smaller than a millimetre across.”

Research leader Dr. Sahar Basiri-Esfahani, now at Swansea University, said the accuracy of the  could change how scientists understand biology.

“We’ll soon have the ability to listen to the sound emitted by living bacteria and cells,” she said.

“This could fundamentally improve our understanding of how these small biological systems function.

“A deeper understanding of these biological systems may lead to new treatments, so we’re looking forward to seeing what future applications emerge.”

The research is published in Nature Communications.

 Explore further: Miniaturised pipe organ could aid medical imaging

More information: Sahar Basiri-Esfahani et al. Precision ultrasound sensing on a chip, Nature Communications (2019). DOI: 10.1038/s41467-018-08038-4

 

New Cancer Research – Converting Cancer Cells to Fat Cells to Stop Cancer’s Spread


A method for fooling breast cancer cells into fat cells has been discovered by researchers from the University of Basel.

The team were able to transform EMT-derived breast cancer cells into fat cells in a mouse model of the disease – preventing the formation of metastases. The proof-of-concept study was published in the journal Cancer Cell. 

Malignant cells can rapidly respond and adapt to changing microenvironmental conditions, by reactivating a cellular process called epithelial-mesenchymal transition (EMT), enabling them to alter their molecular properties and transdifferentiate into a different type of cell (cellular plasticity).

Senior author of the study Gerhard Christofori, professor of biochemistry at the University of Basel, commented in a recent press release: “The breast cancer cells that underwent an EMT not only differentiated into fat cells, but also completely stopped proliferating.”

“As far as we can tell from long-term culture experiments, the cancer cells-turned-fat cells remain fat cells and do not revert back to breast cancer cells,” he explained.

Epithelial-mesenchymal transition and cancer 

Cancer cells can exploit EMT – a process that is usually associated with the development of organs during embryogenesis – in order to migrate away from the primary tumor and form secondary metastases. Cellular plasticity is linked to cancer survival, invasion, tumor heterogeneity and resistance to both chemo and targeted therapies. In addition, EMT and the inverse process termed mesenchymal-epithelial transition (MET) both play a role in a cancer cell’s ability to metastasize.

Using mouse models of both murine and human breast cancer the team investigated whether they could therapeutically target cancer cells during the process of EMT – whilst the cells are in a highly plastic state. When the mice were administered Rosiglitazone in combination with MEK inhibitors it provoked the transformation of the cancer cells into post-mitotic and functional adipocytes (fat cells). In addition, primary tumor growth was suppressed and metastasis was prevented. 

Cancer cells marked in green and a fat cell marked in red on the surface of a tumor (left). After treatment (right), three former cancer cells have been converted into fat cells. The combined marking in green and red causes them to appear dark yellow. Credit: University of Basel, Department of Biomedicine

Christofori highlights the two major findings in the study: 

“Firstly, we demonstrate that breast cancer cells that undergo an EMT and thus become malignant, metastatic and therapy-resistant, exhibit a high degree of stemness, also referred to as plasticity. It is thus possible to convert these malignant cells into other cell types, as shown here by a conversion to adipocytes.”

“Secondly, the conversion of malignant breast cancer cells into adipocytes not only changes their differentiation status but also represses their invasive properties and thus metastasis formation and their proliferation. Note that adipocytes do not proliferate anymore, they are called ‘post-mitotic’, hence the therapeutic effect.”

Since both drugs used in the preclinical study were FDA-approved the team are hopeful that it may be possible to translate this therapeutic approach to the clinic. 

“Since in patients this approach could only be tested in combination with conventional chemotherapy, the next steps will be to assess in mouse models of breast cancer whether and how this trans-differentiation therapy approach synergizes with conventional chemotherapy. In addition, we will test whether the approach is also applicable to other cancer types. These studies will be continued in our laboratories in the near future.”

Journal Reference: Ronen et al. Gain Fat–Lose Metastasis: Converting Invasive Breast Cancer Cells into Adipocytes Inhibits Cancer Metastasis. Cancer Cell. (2019). Available at: https://www.cell.com/cancer-cell/fulltext/S1535-6108(18)30573-7&nbsp;

Gerhard Christofori was speaking to Laura Elizabeth Lansdowne, Science Writer for Technology Networks

Brookhaven National Laboratory – Searching for More Cost Efficient Catalysts for Hydrogen Fuel Cells – Illuminating Nanoparticle Growth With X-Rays


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Brookhaven Lab scientists Mingyuan Ge, Iradwikanari Waluyo, and Adrian Hunt are pictured left to right at the IOS beamline, where they studied the growth pathway of an efficient catalyst for hydrogen fuel cells. Credit: Brookhaven National Laboratory

Hydrogen fuel cells are a promising technology for producing clean and renewable energy, but the cost and activity of their cathode materials is a major challenge for commercialization. Many fuel cells require expensive platinum-based catalysts–substances that initiate and speed up chemical reactions–to help convert renewable fuels into electrical energy. To make hydrogen fuel cells commercially viable, scientists are searching for more affordable catalysts that provide the same efficiency as pure platinum.

“Like a battery, hydrogen fuel cells convert stored chemical energy into electricity. The difference is that you’re using a replenishable fuel so, in principle, that ‘battery’ would last forever,” said Adrian Hunt, a scientist at the National Synchrotron Light Source II(NSLS-II), a U.S. Department of Energy (DOE) Office of Science User Facility at DOE’s Brookhaven National Laboratory. “Finding a cheap and effective catalyst for hydrogen fuel cells is basically the holy grail for making this technology more feasible.”

Taking part in this worldwide search for fuel cell cathode materials, researchers at the University of Akron developed a new method of synthesizing catalysts from a combination of metals–platinum and nickel–that form octahedral (eight-sided) shaped nanoparticles. While scientists have identified this catalyst as one of the most efficient replacements for pure platinum, they have not fully understood why it grows in an octahedral shape. To better understand the growth process, the researchers at the University of Akron collaborated with multiple institutions, including Brookhaven and its NSLS-II.

brookhaven fc 6-scientistsbo

Schematic diagram of the oxygen reduction reaction (reduction of O2 into H2O) on the Pt(110) surface of the PtPb/Pt nanoplates, with purple representing Pt atoms and orange representing Pb atoms. Credit: Brookhaven National Laboratory

“Understanding how the faceted catalyst is formed plays a key role in establishing its structure-property correlation and designing a better catalyst,” said Zhenmeng Peng, principal investigator of the catalysis lab at the University of Akron. “The growth process case for the platinum-nickel system is quite sophisticated, so we collaborated with several experienced groups to address the challenges. The cutting-edge techniques at Brookhaven National Lab were of great help to study this research topic.”

Using the ultrabright x-rays at NSLS-II and the advanced capabilities of NSLS-II’s In situ and Operando Soft X-ray Spectroscopy (IOS) beamline, the researchers revealed the chemical characterization of the catalyst’s growth pathway in real time. Their findings are published in Nature Communications.

“We used a research technique called ambient-pressure x-ray photoelectron spectroscopy (AP-XPS) to study the surface composition and chemical state of the metals in the nanoparticles during the growth reaction,” said Iradwikanari Waluyo, lead scientist at IOS and a co-corresponding author of the research paper. “In this technique, we direct x-rays at a sample, which causes electrons to be released. By analyzing the energy of these electrons, we are able to distinguish the chemical elements in the sample, as well as their chemical and oxidation states.”

Hunt, who is also an author on the paper, added, “It is similar to the way sunlight interacts with our clothing. Sunlight is roughly yellow, but once it hits a person’s shirt, you can tell whether the shirt is blue, red, or green.”

Rather than colors, the scientists were identifying chemical information on the surface of the catalyst and comparing it to its interior. They discovered that, during the growth reaction, metallic platinum forms first and becomes the core of the nanoparticles. Then, when the reaction reaches a slightly higher temperature, platinum helps form metallic nickel, which later segregates to the surface of the nanoparticle. In the final stages of growth, the surface becomes roughly an equal mixture of the two metals. This interesting synergistic effect between platinum and nickel plays a significant role in the development of the nanoparticle’s octahedral shape, as well as its reactivity.

“The nice thing about these findings is that nickel is a cheap material, whereas platinum is expensive,” Hunt said. “So, if the nickel on the surface of the nanoparticle is catalyzing the reaction, and these nanoparticles are still more active than platinum by itself, then hopefully, with more research, we can figure out the minimum amount of platinum to add and still get the high activity, creating a more cost-effective catalyst.”

The findings depended on the advanced capabilities of IOS, where the researchers were able to run the experiments at gas pressures higher than what is usually possible in conventional XPS experiments.

“At IOS, we were able to follow changes in the composition and chemical state of the nanoparticles in real time during the real growth conditions,” said Waluyo.

Additional x-ray and electron imaging studies completed at the Advanced Photon Source (APS) at DOE’s Argonne National Laboratory–another DOE Office of Science User Facility–and University of California-Irvine, respectively, complemented the work at NSLS-II.

“This fundamental work highlights the significant role of segregated nickel in forming the octahedral-shaped catalyst. We have achieved more insight into shape control of catalyst nanoparticles,” Peng said. “Our next step is to study catalytic properties of the faceted nanoparticles to understand the structure-property correlation.”