Scientists have shown they can teleport matter across a city, a development that has been hailed as “a technological breakthrough”.
However, do not expect to see something akin to the Star Trek crew beaming from the planet’s surface to the Starship Enterprise.
Instead, in the two studies, published today in Nature Photonics, separate research groups have used quantum teleportation to send photons to new locations using fibre-optic communications networks in the cities of Hefei in China and Calgary in Canada.
Quantum teleportation is the ability to transfer information such as the properties or the quantum state of an atom — its energy, spin, motion, magnetic field and other physical properties — to another location without travelling in the space between.
Two experiments demonstrate teleportation of particles across real optical fibre networks for first time
Chinese experiment transports two photons per hour across seven kilometres
Canadian experiment transports 17 photons per minute across 6.2 kilometres
While it was first demonstrated in 1997, today’s studies are the first to show the process is technologically possible via a mainstream communications network.
The development could lead to future city-scale quantum technologies and communications networks, such as a quantum internet and improved security of internet-based information.
Dr. Ben Buchler, Associate Professor with the Centre for Quantum Computation and Communication Technology at the Australian National University, said the technical achievement of completing the experiments in a “non-ideal environment” was “pretty profound”.
“People have known how to do this experiment since the early 2000s, but until these papers it hasn’t been performed in fibre communication networks, in situ, in cities,” said Dr. Buchler, who was not involved in the research.
“It’s seriously difficult to do what they have done.”
Watch the YouTube Video: “The Metaphysics of Teleportation” – Dr. Michio Kaku
A cornerstone of quantum teleportation is quantum entanglement, where two particles are intimately linked to each other in such a way that a change in one will affect the other.
Dr. Buchler said quantum teleportation involved mixing a photon with one branch of the entanglement and this joint element was then measured. The other branch of the entanglement was sent to the receiving party or new location.
This original ‘joint’ measurement is sent to the receiver, who can then use that information to manipulate the other branch of the entanglement.
“The thing that pops out is the original photon, in a sense it has indistinguishable characteristics from the one you put in,” Dr Buchler said.
Overcoming technical barriers
He said both teams had successfully overcome technical barriers to ensure the precise timing of photon arrival and accurate polarisation within the fibres.
The Chinese team teleported single protons using the standard telecommunications wavelength across a distance of seven kilometres, whiled the Canadian team teleported single photons up to 6.2 kilometres.
But work remained to increase the speed of the system with the Chinese group teleporting just two photons per hour and the Canadians a faster rate of 17 photons per minute.
Dr. Buchler said the speeds meant the development had little immediate practical value, but “this kind of teleportation is part of the protocol people imagine will be able to extend the range of quantum key distribution” — a technique used to send secure encrypted messages.
In the future scientists envision the evolution of a quantum internet that would allow the communication of quantum information between quantum computers.
Quantum computers on their own would allow fast computation, but networked quantum computers would be more powerful still.
Dr. Buchler said today’s studies were a foundation stone toward that vision as it showed it was possible to move quantum information from one location to another within mainstream networks without destroying it.
Yes … a LOT more work has to be done however before we “Warp” and “Beam” … but to put it into the words of ‘The Good Doctor’ …
“Damit Jim, I’m ONLY a doctor!” (Highly Logical) “Live long and Prosper!”
WHICH is the world’s most innovative country? Answering this question is the aim of the annual Global Innovation Index and a related report, which were published this morning by Cornell University, INSEAD, a business school, and the World Intellectual Property Organisation.
The ranking of 140 countries and economies around the world, which are scored using 79 indicators, is not surprising: Switzerland, Britain, Sweden, the Netherlands and America lead the pack.
But the authors also look at their data from other angles, for instance how countries do relative to their economic development and the quality of innovation (measured by indicators such as university rankings). In both cases the results are more remarkable. The chart above shows that in innovation many countries in Africa punch above their economic weight. And the chart below indicates that, even though China is now churning out a lot of patents, it is still way behind America and other rich countries when it comes to innovation quality.
Before the dawn of the new millennium, the then President of the USA Bill Clinton was invited by Science magazine to write an editorial. In the one-page piece, Science in the 21st century, he wrote: “Imagine a new century, full of promise, molded by science, shaped by technology, powered by knowledge. We are now embarking on our most daring explorations, unraveling the mysteries of our inner world and charting new routes to the conquest of disease” . In 2000, the US government firmly kicked off its significant and influential National Nanotechnology Initiative (NNI) program after integrating all resources from Federal agencies, including National Science Foundation, Department of Defense, Department of Energy, Department of Health and Human Services (NIH), National Institute of Standard Technology (NIST), National Aeronautics and Space Administration (NASA), Environmental Protection Agency (EPA), Homeland Security, United States Department of Agriculture (USDA), and Department of Justice.
The NNI established four goals:
(1) to advance a world-class nanotechnology research and development program;
(2) to foster the transfer of new technologies into products for commercial and public benefit;
(3) to develop and sustain educational resources, a skilled workforce, and supporting infrastructure and tools to advance nanotechnology; and
(4) to support responsible development of nanotechnology. The NNI significantly pushes nanotechnology research forward. In 2006, the prominence of nanotechnology research began to exceed medical research in terms of publication rate. That trend appears to be continuing as a result of the growth of products in commerce using nanotechnology and, for example, five-fold growth in number of countries with nanomaterials research centers.
The nanoscience and nanotechnology subject category of the Journal Citation Report (JCR) published by Thomson Reuters has increased rapidly. Correspondingly, both impact factors (published by Thomson Reuters) and SCImago Journal Rank values (SJR is published by Elsevier’s Scopus and powered by Google’s PageRank algorithms) of journals in the nanotechnology subject category have increased rapidly . The aggregate impact factor of nanoscience and nanotechnology has been rising at a breathtaking rate, compared with other subject categories, reaching the top 10 after 2011. The hype and hope of nanotechnology challenging many previously unimaginable goals are especially high now, and many believe in forthcoming breakthroughs in the areas of nanomaterial-based diagnostic imaging, complementation of diagnostic tools combined with therapeutic modalities (i.e., theranostics), or nanoencapsulation and nano-carriers of biotechnology products.
Today, it is estimated that total NNI funding, including the fiscal year 2014, is about $170 billion. Currently, there are more than 60 countries that have launched national nanotechnology programs . Governments and industry have invested millions of dollars in research funding in this rapidly growing field. By 2015, approximately one quarter trillion dollars will have been invested in nanotechnology by the American government and private sectors collectively. The continuous strategic investment in nanotechnology has made the United States a global leader in the field.
Ten years ago, when AAAS celebrated the 125th anniversary of the journal Science, it invited the President of Chinese Academy of Science (CAS) Chunli Bai to write an essay for the special section Global Voice of Science. The CAS President Chunli Bai’s essay, Ascent of Nanoscience in China described the then development of nanotechnology and nanoscience in the country and openly announced the government’s ambition to compete with other countries in the field. In 2006, the Chinese government announced its Medium and Long-term Plan for the Development of Science and Technology (2006–2020), which identified nanotechnology as “a very promising area that could give China a chance of great-leap-forward development”. The plan introduced the new Chinese Science & Technology policy guidelines, which were later implemented by the Ministry of Science and Technology (MOST) that operates Nanoscience Research as a part of the State Key Science Research Plans. So far the Nanoscience Research program has invested about 1.0 billion RMB to support 28 nanotechnology projects. All of these endeavors led to the recent significantly rapid rise of nanotechnology in China as evidenced by its publications, industrial R&D and applications in the field.
The rapid development of nanotechnology-based science and technology in China attracted worldwide attention including from Demos, one of the UK’s most influential think tanks. Led by Wilsdon and Keeley, Demos completed an 18-month study, interviewing many leading scientists and policy makers of 71 Asian organizations, including two well-known Chinese nanotechnology academics Dr. Chen Wang (the then Director of National Center for Nanoscience and Technology) and Academician Zihe Rao (Director of CAS Institute of Biophysics).
After completion of the project, Wilsdon and Keeley published their findings in the book, China: The next science superpower?” . The authors wrote, “China in 2007 is the world’s largest technocracy: a country ruled by scientists and engineers who believe in the power of technology to deliver social and economic progress. Right now, the country is at an early stage in the most ambitious program of research investment since John F Kennedy embarked on the race to the moon. But statistics fail to capture the raw power of the changes that are under way, and the potential for Chinese science and innovation to head in new and surprising directions. Is China on track to become the world’s next science superpower?” Indeed, in recent years, China has emerged not only as a mass manufacturer, but also as one of the world’s leading nanotechnology nations. Many nanomaterial-based semiconductor products come from China and the country dominates in the nanotechnology area of most-cited academic articles: the top eighteen out of the twenty scholars are of Chinese origin .
Changes in nanotechnology-related geopolitical landscape
With strong governmental and private sector supports, nanotechnology and nanoscience R&D has developed rapidly in both the USA and China. As shown in Fig. 1A, from 2003 to 2013, the USA led in the area of global nanotechnology publications in terms of the numbers of papers and their quality determined by the number of citations and H-index. China followed USA in the field. For instance, the total nanotechnology publications from USA were 160,870 with total citations of 4056,278, whereas, China published 154,946 papers with total citations of 2049,072. The quality of an article is usually judged by the number of citations it receives, although other measures such as the number of downloads are becoming more accepted and used .
Based on the total number of publications and related citations, we have used weighted statistics to calculate the top countries actively involved in nanotechnology research (see original publication for full details). The statistics show that USA ranks number one, followed by China, Germany, Japan, Korea, France, UK, India, Italy, Spain, Taiwan (China), and others (Fig. 1A). EU countries are not too far behind in the field. Further analysis indicates that the number of nanotechnology-related publications increased from 23,957 in 2003 to 107,371 in 2013 world-wide (an increase of 4.48-folds). Among them, 3592 and 30.479 papers were contributed by China in 2003 and in 2013, respectively, that is an increase of 8.49 folds, which is about 2-fold higher than the global publication increase rate.
Bibliometric data of twenty leading nanotechnology journals shows that the USA is leading in nanotechnology research by far (see original publication for full details). The USA contributed 22,067 papers to the twenty journals from 2003 to 2013, whereas, China only published 3421 papers in these journals. If the analysis is limited to papers published in journals with an impact factor >20, the USA originated 1068 papers, followed by EU countries Germany (221), UK (193), France (149), and finally Japan (121). China only produced 76 papers with an impact factor >20, demonstrating that China has some significant hurdles to overcome to join the world’s top countries in nanotechnology development.
Interestingly, China is not lagging behind world leaders in all areas, for example, the gap between the USA and China is narrower in the field of nanomaterial research. Publications from China in Advanced Materials, Advanced Functional Materials, and Angew. Chem. Int. Edit. are not much less than those from the USA. In fact, China is leading in nanocomposites, chemical synthesis, and photocatalysis research (Fig. 1B and C). Chinese scientists published 1712 and 1580 papers in chemical synthesis and photocatalysis (from 2003 to 2013), respectively. The numbers exceed those from India, South Korea, Japan, USA, France, Germany, UK and Italy combined, suggesting that Chinese researchers have evolved their own research focuses and strengths over the years. On the other hand, this fact may also indicate an over-investment of resources in this area.
A list of the top ten universities and institutes world-wide (see original paper for full details), Top 10 Universities for Nanotechnology and Materials Science (U.S. has 5 in the Top 10) as well as those located within USA or China who contribute the most nanotechnology publications, reveals that the authorship of China’s nanotechnology publications is mostly concentrated in a small group of prestigious institutes and universities, reflecting the more centralized governance of China science, while authorship in the USA is more widely distributed. Indeed, the CAS possesses more resources than other competitors in China.
The geopolitical differences between the USA and China are also reflected in nanotechnology-related patent applications and industrialization. The numbers of nanotechnology-related patent applications to the US Patent and Trademark Office (USPTO), or the State Intellectual Property Office of China (SIPO) have increased from 405 in 2000 to 3729 in 2008 in USA, or from 105 in 2000 to 5030 in 2008 in China .
According to the China Patent Abstract Database managed by the SIPO, there were 30,863 nanotechnology patent applications from 1985 to 2009, and most of them were published after 2003. The central government has already built several state-level nanotechnology R&D incubators or bases, including the National Center for Nanoscience and Technology of China in Beijing, The State Engineering Research Center for Nanotechnology and Applications in Shanghai, National Institute of Nanotechnology and Engineering in Tianjin, Zhejiang–California International NanoSystems Institute, International Innovation Incubator of Nanotechnology, in Suzhou. In general, Beijing and Shanghai remain the two dominant nanotechnology centers, followed by Jiangsu and Zhejiang, reflecting the regional divergence of Chinese nanotechnology development .
The China–USA relationship is as compelling as it is complex. Approximately, one out of ten professionals in Silicon Valley’s high-tech workforce is from mainland China . In today’s global economy, the two great countries compete with each other in nanotechnology in a parallel and compatible manner. Historically, the United States has led the global high-tech and nanotechnology fields. However, the gap between USA and China in nanotechnology has narrowed significantly in recent years and American nanotechnology leadership faces challenges from all over the world.
With improved investment in research infrastructure and funding, China is sustaining the fastest economic growth in the world. Citizens’ participation in nanoscience and nanotechnology-related consensus conferences or stakeholder dialogues has become normal. This has not only had a significant impact on nanotechnology development in China, but also is democratically legitimate. Interest-based civil society interventions play an important role in the polycentric governance of nanoscience and nanotechnology to ensure that the related policies and regulations are made prudently after open argument and discussions . It would be interesting to watch, debate and decide which type of governmental system, the centralized one-party or the almost equally-divided two-party system, can more efficiently and effectively utilize public resources to produce nanotechnology products that better serve their own taxpayers, and the worldwide community as well.
Recently, researchers at Tsinghua University, China have proposed a graphene-based nanostructured lithium metal anode for lithium metal batteries to inhibit dendrite growth and improve electrochemistry performance. They report their findings in Advanced Materials, published on March 16, 2016.
“Widely used lithium-ion batteries cannot satisfy the increasing requirement of energy storage systems in portable electronics and electric vehicles. New lithium metal anode batteries, like Li-S and Li-air batteries, are highly sought. Lithium metal provides an extremely high theoretical specific capacity, which is almost 10 times more energy than graphite,” said Prof. Qiang Zhang, at the Department of Chemical Engineering, Tsinghua University. “However, the practical applications of lithium metals are strongly hindered by lithium dendrite growth in continuous cycles. This induces safety concerns. The lithium dendrites may cause internal short circuits resulting in fire. Furthermore, the formation of lithium dendrites induces very low cycling efficiency.” The dendrite growth and unstable solid electrolyte interphase consume large amount of lithium and electrolyte, and therefore leading to irreversible battery capacity losses. Consequently, inhibiting the dendrites growth is highly expected.
Many approaches have been proposed to retard the growth of dendrites through electrolyte modification, artificial solid electrolyte interphase layers, electrode construction, and others. “We noticed that by decreasing the local current density heavily, lithium dendrite growth could be efficiently inhibited. Based on this concept, we employed unstacked graphene with an ultrahigh specific surface area to build a nanostructured anode. And it turned out to be a very efficient idea,” said Rui Zhang, a Ph.D. student and the first author. “Additionally, we have employed the dual-salt electrolyte to acquire more stable and more flexible solid electrolyte interphase, which can protect the lithium metal from further reactions with electrolyte.”
This graphene-based anode offered great improvement, including (1) ultralow local current density on the surface of graphene anode (a ten-thousandth of that on routine Cu foil-based anodes) induced by the large specific surface area of 1666 m2 g-1, which inhibited dendrite growth and brought uniform lithium deposition morphology; (2) high stable cycling capacity of 4.0 mAh mg-1 induced by the high pore volume (1.65 cm3 g-1) of unstacked graphene, over 10 times of the graphite anode in lithium-ion batteries (0.372 mAh mg-1); (3) high electrical conductivity (435 S cm-1), leading to low interface impedance, stable charging/discharging performance, and high cycling efficiencies.
“We hope that our research can point out a new strategy to deal with the dendrite challenge in lithium metal anodes. The ultralow local current density induced by conductive nanostructured anodes with high specific surface area can help improve the stability and electrochemistry performance of lithium metal anodes,” said Xin-Bing Cheng, a co-author of the work. Future investigation is required to design preferable anode structures and to produce more protective solid electrolyte interphase layers. The researchers also call for additional study of the diffusion behavior of Li ions and electrons in the process of lithium depositing and stripping to advance the commercial applications of lithium metal anodes.
More information: R. Zhang, X.-B. Cheng, C.-Z. Zhao, H.-J. Peng, J.-L. Shi, J.-Q. Huang, J. Wang, F. Wei, Q. Zhang. Conductive Nanostructured Scaffolds Render Low Local Current Density to Inhibit Lithium Dendrite Growth. Adv. Mater. 2016, 28, 2155-2162. DOI: 10.1002/adma.201504117.
*** Departing from GNT™‘s ‘normal’ Nanotechnology beat, we turn to in this series of 3 articles the subject “matter” (pardon the punny) of Nuclear Fission, Fusion and Hybrid Fission-Fusion. The interesting cross-pollination of course is the future of “clean, abundant, cheap energy” for our planet of 7 Billion+ people now and going toward 9 Billion by 2042. Please share with us and our readership, your thoughts and any comments.
“Great Things from Small Things!” ~ Team GNT™
“Discover ~ Develop ~ Position ~ Commercialize ~ Exit”
August 3, 2015
China is going to build its first hybrid fusion-fission reactor by 2030, according to local media reports. The reactor is expected to recycle nuclear waste making energy production more environmentally friendly.
The ambitious plan is in the works at the top secret Chinese Academy of Engineering Physics in Sichuan, where China develops its nuclear weapons, China Daily Mail reports. The plans were announced in a study published in the Science and Technology Daily, an official newspaper of the Ministry of Science and Technology.
The experimental research platform will be built by 2020 while the whole system could be launched by 2030, said Huang Hongwen, the deputy project manager, China Daily Mail reported Saturday.
Researchers believe that hybrid reactors will generate twice as much electricity as modern reactors. These reactors are also believed to be safer as they can be immediately stopped by cutting the external power supply.
Today reactors use only fission technology which means dividing atoms in half while future fusion-fission technology will merge two atoms in one. The core of the new hybrid reactor will be a fusion reactor which will be powered by a 60 trillion amperes fission reactor.
The basic principle of the hybrid reactor is recycling uranium-238, which is the main component of nuclear waste, into new fuel. Such a reactor will become a breakthrough in environmentally friendly technologies and in particular a solution of nuclear wastes problem for China, who lacks recycling facilities and has to store the waste inside nuclear energy plants.
Hybrid fusion-fission reactors can also solve another vital problem for China – uranium shortages. According to the study China can meet its uranium demands for only a century, while using fusion-fission technologies will provide it with uranium for several thousand years.
Some scientists have doubts over whether Chinese plans are realistic. “A viable fusion reactor is nowhere in sight, not to mention a hybrid,” an unnamed physicist from Tsinghua University told the SCMP.
“It’s like talking about hybrid cars before the internal combustion engine was even invented. We will be lucky to have the first fusion reactor in 50 years. I don’t think a hybrid can be built way before that”, he added.
China is not the only country which has tried to create a hybrid fusion-fission reactor. Similar projects are being developed in Russia, Japan, the EU and the USA. China, however, is the first country to have planned exact dates.
Russia develops hybrid fusion-fission reactor, offers China role
October 15, 2014
Russia is developing a hybrid nuclear reactor that uses both nuclear fusion and fission, said head of leading nuclear research facility. The project is open for international collaboration, particularly from Chinese scientists.
A hybrid nuclear reactor is a sort of stepping stone to building a true nuclear fusion reactor. It uses a fusion reaction as a source of neutrons to initiate a fission reaction in a ‘blanket’ of traditional nuclear fuel.
The approach has a number of potential benefits in terms of safety, non-proliferation and cost of generated energy, and Russia is developing such a hybrid reactor, according to Mikhail Kovalchuk, director of the Kurchatov Research Center.
“Today we have started the realization of a distinctively new project. We are trying to combine a schematically operational nuclear plant reactor with a ‘tokamak’ to create a hybrid reactor,” he told RIA Novosti, referring to a type of fusion reactor design.
“This project is open for our colleagues, the Chinese in the first place. It’s being discussed,” he added.
Being a leading producer in civilian nuclear energy industry, Russia would benefit from improving its plant designs. A hybrid fusion-fission reactor may be several times more efficient than a traditional fission reactor. And building one is “a goal for tomorrow” rather than the distant future, as is the case for a fusion reactor like the famous France-based International Thermonuclear Experimental Reactor (ITER) that Russia collaborates on, Kovalchuk said.
Harnessing nuclear fusion for energy generation has been elusive for years. So far no industrial-scale design managed to produce more energy than it consumes to start the reaction, though the California-based National Ignition Facility (NIF) was reported to have achieved this goal on lab-scale by bombarding a fuel pellet with 192 powerful lasers.
But nuclear fusion produces neutrons, and those can initiate fission in traditional nuclear fuel like uranium or plutonium. In a hybrid reactor the core fusion zone consumes energy to heat up outer fissile blanket, which on its part generates energy.
A hybrid reactor plant would likely be even more costly that regular nuclear power plants are, considering the complexities of the design. But it is inherently safer, since the reaction in the fissile blanket would be sub-critical, that is, it won’t sustain itself. In an emergency it could be simply stopped in a matter of seconds by turning off the fusion core, as opposed to using dampening rods in a traditional reactor.
Another benefit of a hybrid design is that it ‘burns down’ fissile materials leaving little by-products. So it won’t produce radioactive waste and can even treat spent nuclear fuel from regular reactors.
Rather than taking NIF’s pellet-and-lasers design for the fusion reactor, Russia wants to use a tokamak, a reactor that suspends superheated plasma with powerful magnetic fields, as the core of a hybrid reactor. ITER uses the design too.
A similar tokamak-based project of a hybrid fusion-fission nuclear reactor is being developed at the University of Texas at Austin, although researchers there eye nuclear waste disposal rather than electricity generation as the goal.
February 13, 2014
Nuclear fusion breakthrough: US scientists make crucial step to limitless power
A metallic case called a hohlraum holds the fuel capsule for NIF experiments (Image from llnl.gov)
A team of scientists in California announced Wednesday they are one step closer to developing the almost mythical pollution-free, controlled fusion-energy reaction, though the goal of full “ignition” is still far off.
Researchers at the federally-funded Lawrence Livermore National Laboratory revealed in a study released Wednesday in the peer-reviewed journal Nature that, for the first time, one of their experiments has yielded more energy out of fusion than was used in the fuel that created the reaction.
In a 10-story building the size of three football fields, the Livermore scientists “used 192 lasers to compress a pellet of fuel and generate a reaction in which more energy came out of the fuel core than went into it,” wrote the Washington Post. “Ignition” would mean more energy was produced than was used in the entire process.
“We’re closer than anyone’s gotten before,” said Omar Hurricane, a physicist at Livermore and lead author of the study. “It does show there’s promise.”
The process ultimately mimics the processes in the core of a star inside the laboratory’s hardware. Nuclear fusion, which is how the sun is heated, creates energy when atomic nuclei fuse and form a larger atom.
“This isn’t like building a bridge,” Hurricane told USA Today in an interview. “This is an exceedingly hard problem. You’re basically trying to produce a star, on a small scale, here on Earth.”
A fusion reactor would operate on a common form of hydrogen found in sea water and create minimal nuclear waste while not being nearly as volatile as a traditional nuclear-fission reactor. Fission, used in nuclear power plants, works by splitting atoms.
Hurricane said he does not know how long it will take to reach that point, where fusion is a viable energy source.
“Picture yourself halfway up a mountain, but the mountain is covered in clouds,” he told reporters on a conference call Wednesday. “And then someone calls you on your satellite phone and asks you, ‘How long is it going to take you to climb to the top of the mountain?’ You just don’t know.”
The beams of the 192 lasers Livermore used can pinpoint extreme amounts of energy in billionth-of-a-second pulses on any target. Hurricane said the energy produced by the process was about twice the amount that was in the fuel of the plastic-capsule target. Though the amount of energy yielded equaled only around 1 percent of energy delivered by the lasers to the capsule to ignite the process.
“When briefly compressed by the laser pulses, the isotopes fused, generating new particles and heating up the fuel further and generating still more nuclear reactions, particles and heat,” wrote the Washington Post, adding that the feedback mechanism is known as “alpha heating.”
Debbie Callahan, co-author of the study, said the capsule had to be compressed 35 times to start the reaction, “akin to compressing a basketball to the size of a pea,” according to USA Today.
While applauding the Livermore team’s findings, fusion experts added researchers have “a factor of about 100 to go.”
“These results are still a long way from ignition, but they represent a significant step forward in fusion research,” said Mark Herrmann of the Sandia National Laboratories’ Pulsed Power Sciences Center. “Achieving pressures this large, even for vanishingly short times, is no easy task.”
Livermore is the site of the multi-billion-dollar National Ignition Facility, funded by the National Nuclear Security Administration. Fusion experiments aren’t the only function of the lab; for example, it also studies the processes of nuclear weapon explosions.
Long-pursued by scientists dating back to Albert Einstein, fusion energy does not emit greenhouse gases or leave behind radioactive waste. Since the 1940s, researchers have employed magnetic fields to contain high-temperature hydrogen fuel. Laser use began in the 1970s.
“We have waited 60 years to get close to controlled fusion,” said, Steve Cowley, of the United Kingdom’s Culham Center for Fusion Energy. He added scientists are “now close” with both magnets and lasers. “We must keep at it.”
Stewart Prager – director of the Princeton Plasma Physics Laboratory, which studies fusion using magnets – told the Post he was optimistic about fusion energy’s future.
“In 30 years, we’ll have electricity on the grid produced by fusion energy – absolutely,” Prager said. “I think the open questions now are how complicated a system will it be, how expensive it will be, how economically attractive it will be.”
Two Chinese firms have beaten global competition to launch phones with touch screens, batteries and thermal conduction incorporating graphene, a recently isolated material with outstanding electrical, chemical and mechanical properties.
A batch of 30,000 such phones was jointly put on sale by the Moxi and Galapad technology firms on Monday in southwest China’s Chongqing municipality, Xinhua news agency reported.
The use of graphene can make touch screens more sensitive and prolong battery life by 50 percent, according to the producers.
The key technology for the new phones, which use the Android system and will sell for 2,499 yuan ($406) each, was developed by the Chinese Academy of Sciences.
Graphene is a single layer of carbon atoms in a honeycomb lattice. It was first isolated in 2004. Scientists worldwide have been rushing to test it.
China leads the world in the mass production of graphene films for phone and computer touch screens. In 2013, a production line capable of producing tens of millions of graphene films every year went into operation in Chongqing.
Recently discovered family of 2-D materials could one day yield high-performance batteries, flexible electronics, and more.
A recently discovered family of carbides and nitrides first started to catch the attention of researchers in 2012. Referred to as MXenes (pronounced “maxenes”), the materials turned heads because they are electrically conductive, robust, abundant, and stable as nearly atomically thin sheets—properties that could be useful for making high-performance batteries.
MXenes are now looking even better, as researchers have just shown that these materials are also strong and flexible, exhibit high electrical capacitance, and can easily be prepared as composites and moldable clays. The new discoveries suggest that MXenes may also be useful for applications such as flexible and wearable electronics and are attracting more scientists to this intriguing family of materials. Some of those researchers gathered at last month’s Materials Research Society meeting in Boston to discuss their latest findings and ideas for developing those applications.
The history of MXenes is brief. In 2011, Yury Gogotsi and Michel W. Barsoum, materials science professors at Drexel University, were studying ways to make anodes for lithium-ion batteries that outlast standard graphite anodes. The team’s earlier work suggested that a family of electrically conducting carbides and nitrides were promising candidate materials. Those compounds are known as the MAX phases, where M refers to an early transition metal, A symbolizes main-group elements such as aluminum and silicon, and X represents carbon or nitrogen.
The Drexel team treated Ti3AlC2 and other MAX phases with concentrated hydrofluoric acid to selectively remove some of the atoms from the starting materials. The goal was to make enough room in the anode lattice for Li ions to reversibly insert themselves during battery charging and discharging. The process worked. The group ended up with electrochemically active materials that performed admirably in battery tests.
But the Drexel team got more than they bargained for. The group was surprised to learn that the acid treatment had completely removed the Al layers (the A component in MAX) and exfoliated the crystals into microscopic two-dimensionalsheets of Ti3C2. Excited by the discovery of new 2-D materials with graphenelike morphology, the team named the materials MXenes. Within a few months, they showed that the acid treatment could be used to make many 2-D materials by exfoliating additional compounds such as Ti2AlC, Ta4AlC3, (Ti0.5Nb0.5 )2AlC, (V0.5Cr0.5)3AlC2, and Ti3AlCN (ACS Nano 2012, DOI: 10.1021/nn204153h).
Word began spreading quickly. Thanks in part to graphene’s popularity, Gogotsi says, MXenes “have been riding a wave of excitement about 2-D materials.” He adds that researchers are enthusiastic about MXenes because they see what may potentially be a huge new area of materials science emerging.
That enthusiasm is especially noticeable in Gogotsi’s and Barsoum’s groups. The accelerated pace of research by the combined team has led to publication of several journal papers in just the past few weeks. Those studies have common themes—convenient processing methods and more functional forms of MXenes.
Available only as powders until recently, MXenes (titanium carbide shown above) can now be made as large, flexible, electrically conductive films, an advantage for mobile energy applications.
Credit: Proc. Natl. Acad. Sci. USA
In the early studies in this field, the separated MXene sheets were nanometer-thick flakes with lateral dimensions reaching a few micrometers. Although the particulate (powdered) form of such materials has useful properties, powders have limited function and offer limited processing options.
So the team developed a vacuum filtration method that fuses the flakes into freestanding macroscopic thin films. They also devised procedures for making MXene-polymer composites, which could turn these materials into something with commercial value.
Collectively, the thin films are flexible, foldable, and strong enough to be handled repeatedly without being damaged. They are also electrically conductive, hydrophilic, and highly stable in water. Among other findings, the team observed that pure MXene films conduct electricity better and store more charge than graphene and carbon nanotube “paper” (Proc. Natl. Acad. Sci. USA 2014, DOI: 10.1073/pnas.1414215111). The team also found that polymers such as polyvinyl alcohol mix intimately with titanium carbide (the most studied MXene), forming alternating MXene-PVA-MXene layered structures. The composites are up to 400% stronger than pure MXene films.
This freestanding titanium carbide-PVA composite film derives its high strength and flexibility from intimate mixing of MXene (dark) and polymer layers (light).
Credit: Proc. Natl. Acad. Sci. USA
The Drexel team has also devised a method for forming MXene-carbon nanotube composite films (Adv. Mater. 2014, DOI: 10.1002/adma.201404140). Similar to the polymer composites, the nanotube composites are strong and flexible films with an alternating layer structure. Gogotsi explains that inserting polymers or nanotubes between the MXene layers enables electrolyte ions to diffuse more easily through the MXenes, which is key for flexible energy storage applications. But unlike polymers, carbon nanotubes also enable electrons to shuttle back and forth. Initial tests show that MXene-carbon nanotube films work well as supercapacitor electrodes, with no degradation in performance in 10,000 charging cycles.
And in another just-published paper, the Drexel group reported a simpler and safer route to MXene films. The team showed that concentrated hydrofluoric acid, a hazardous chemical that has been used until now to prepare all MXenes, can be avoided by treating the starting materials instead with a solution of lithium fluoride and hydrochloric acid. The resulting material can easily be molded like clay to form conductive films or solids of arbitrary shape (Nature 2014, DOI: 10.1038/nature13970).
Drexel’s Chang (Evelyn) Ren displays a “paper” airplane she made from a MXene film, showing that the material is strong enough to be handled and folded repeatedly. Credit: Mitch Jacoby/C&EN
Credit: Mitch Jacoby/C&EN
Several other research groups have also begun studying MXenes. At the University of Bath, in England, for example, Christopher Eames and M. Saiful Islam computationally screened the interactions of Li+, Na+, K+, and Mg2+ with a large number of MXenes in search of new high-capacity battery materials. They find that in terms of voltage and charge capacity the most promising M2C materials contain light transition metals such as scandium, titanium, vanadium, and chromium (J. Am. Chem. Soc. 2014, DOI: 10.1021/ja508154e).
And at Oak Ridge National Laboratory, Paul R. C. Kent and coworkers are also searching for new battery materials—in this case, for anodes for non–Li-ion batteries. They find that for Mg- and Al-ion batteries, bare MXenes have higher charge capacities and enable greater ion mobilities than O-terminated MXenes. They also find that the metal ion storage mechanism is more complicated in MXenes than in other materials. It involves reversible conversion reactions, ion insertion and extraction, and metal plating and stripping (ACS Nano 2014, DOI: 10.1021/nn503921j).
Energy applications aren’t the only ones on the minds of MXene researchers. At Yanshan University, in Qinhuangdao, China, scientists have found that titanium carbide (Ti3C2)with hydroxyl group terminations efficiently soaks up lead ions even in the presence of high concentrations of calcium and magnesium ions, suggesting a way to purify drinking water (J. Am. Chem. Soc. 2014, DOI: 10.1021/ja500506k). And according to a just-published study from Peking University, a polymer-brush-grafted form of V2C responds to changes in temperature and CO2 concentration, indicating that the hybrid material may function as a sensor (Chem. Commun. 2014, DOI: 10.1039/c4cc07220k).
It’s hard to guess what the next couple of years will bring to this new area of materials science. But it’s clear that this is only the beginning, Gogotsi says. Researchers have examined just a handful of the MAX phase starting materials, yet more than 70 of those compounds are known, he notes. “There is no reason to think that we have seen the best materials with the most impressive properties.”
We report high-efficiency blue-violet quantum-dot-based light-emitting diodes (QD-LEDs) by using high quantum yield ZnCdS/ZnS graded core–shell QDs with proper surface ligands. Replacing the oleic acid ligands on the as-synthesized QDs with shorter 1-octanethiol ligands is found to cause a 2-fold increase in the electron mobility within the QD film.
Such a ligand exchange also results in an even greater increase in hole injection into the QD layer, thus improving the overall charge balance in the LEDs and yielding a 70% increase in quantum efficiency. Using 1-octanethiol capped QDs, we have obtained a maximum luminance (L) of 7600 cd/m2 and a maximum external quantum efficiency (ηEQE) of (10.3 ± 0.9)% (with the highest at 12.2%) for QD-LEDs devices with an electroluminescence peak at 443 nm. Similar quantum efficiencies are also obtained for other blue/violet QD-LEDs with peak emission at 455 and 433 nm. To the best of our knowledge, this is the first report of blue QD-LEDs with ηEQE > 10%. Combined with the low turn-on voltage of ∼2.6 V, these blue-violet ZnCdS/ZnS QD-LEDs show great promise for use in next-generation full-color displays.
The prospect of turning coal into fluorescent particles may sound too good to be true, but the possibility exists, thanks to scientists at Rice University.
The Rice lab of chemist James Tour found simple methods to reduce three kinds of coal into graphene quantum dots (GQDs), microscopic discs of atom-thick graphene oxide that could be used in medical imaging as well as sensing, electronic and photovoltaic applications.
Coal yields production of graphene quantum dots
Band gaps determine how a semiconducting material carries an electric current. In quantum dots, band gaps are responsible for their fluorescence and can be tuned by changing the dots’ size. The process by Tour and company allows a measure of control over their size, generally from 2 to 20 nanometers, depending on the source of the coal.
An illustration shows the nanostructure of bituminous coal before separation into graphene quantum dots. Courtesy of the Tour Group
There are many ways to make GQDs now, but most are expensive and produce very small quantities, Tour said. Though another Rice lab found a way last year to make GQDs from relatively cheap carbon fiber, coal promises greater quantities of GQDs made even cheaper in one chemical step, he said.
“We wanted to see what’s there in coal that might be interesting, so we put it through a very simple oxidation procedure,” Tour explained. That involved crushing the coal and bathing it in acid solutions to break the bonds that hold the tiny graphene domains together.
“You can’t just take a piece of graphene and easily chop it up this small,” he said.
Tour depended on the lab of Rice chemist and co-author Angel Martí to help characterize the product. It turned out different types of coal produced different types of dots. GQDs were derived from bituminous coal, anthracite and coke, a byproduct of oil refining.
An electron microscope image shows the stacking layer structure of graphene quantum dots extracted from anthracite. The scale bar equals 100 nanometers. Courtesy of the Tour Group.
The coals were each sonicated in nitric and sulfuric acids and heated for 24 hours. Bituminous coal produced GQDs between 2 and 4 nanometers wide. Coke produced GQDs between 4 and 8 nanometers, and anthracite made stacked structures from 18 to 40 nanometers, with small round layers atop larger, thinner layers. (Just to see what would happen, the researchers treated graphite flakes with the same process and got mostly smaller graphite flakes.)
Tour said the dots are water-soluble, and early tests have shown them to be nontoxic. That offers the promise that GQDs may serve as effective antioxidants, he said.
Medical imaging could also benefit greatly, as the dots show robust performance as fluorescent agents.
“One of the problems with standard probes in fluorescent spectroscopy is that when you load them into a cell and hit them with high-powered lasers, you see them for a fraction of a second to upwards of a few seconds, and that’s it,” Martí said. “They’re still there, but they have been photo-bleached. They don’t fluoresce anymore.”
Testing in the Martí lab showed GQDs resist bleaching. After hours of excitation, Martí said, the photoluminescent response of the coal-sourced GQDs was barely affected.
Rice University chemist James Tour, left, and graduate student Ruquan Ye show the source and destination of graphene quantum dots extracted from coal in a process developed at Rice. Tour said the fluorescent particles can be drawn in bulk from coal in a one-step process. Photo by Jeff Fitlow
That could make them suitable for use in living organisms. “Because they’re so stable, they could theoretically make imaging more efficient,” he said.
A small change in the size of a quantum dot – as little as a fraction of a nanometer – changes its fluorescent wavelengths by a measurable factor, and that proved true for the coal-sourced GQDs, Martí said.
Low cost will also be a draw, according to Tour. “Graphite is $2,000 a ton for the best there is, from the U.K.,” he said. “Cheaper graphite is $800 a ton from China. And coal is $10 to $60 a ton.
“Coal is the cheapest material you can get for producing GQDs, and we found we can get a 20 percent yield. So this discovery can really change the quantum dot industry. It’s going to show the world that inside of coal are these very interesting structures that have real value.”
Co-authors of the work include graduate students Ruquan Ye, Changsheng Xiang, Zhiwei Peng, Kewei Huang, Zheng Yan, Nathan Cook, Errol Samuel, Chih-Chau Hwang, Gedeng Ruan, Gabriel Ceriotti and Abdul-Rahman Raji and postdoctoral research associate Jian Lin, all of Rice. Martí is an assistant professor of chemistry and bioengineering. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of mechanical engineering and materials science and of computer science.
“The main innovation of this work is that it developed a concept smart window device for simultaneous generation and saving of energy.”
Engineers have long battled to incorporate energy-generating solar cells into window panes without affecting their transparency.
Gao’s team discovered that a material called vanadium oxide (VO2) can be used as a transparent coating to regulate infrared radiation from the sun.
VO2 changes its properties based on temperature. Below a certain level it is insulating and lets through infrared light, while at another temperature it becomes reflective.
A window in which VO2 was used could regulate the amount of sun energy entering a building, but also scatter light to solar cells the team had placed around their glass panels, where it was used to generate energy with which to light a lamp, for example.
“This smart window combines energy-saving and generation in one device, and offers potential to intelligently regulate and utilise solar radiation in an efficient manner,” the study authors wrote in the journal Nature Scientific Reports.