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Processable High Internal Phase Pickering Emulsion Using Depletion Attraction
Professor Siyoung Choi’s research team from the KAIST Department of Chemical & Biomolecular Engineering used physical force to successfully produce a stable emulsion.
Emulsions, commonly known as cosmetic products, refer to stably dispersed structures of oil droplets in water (or water droplets in oil). Pickering emulsions refer to emulsions stabilized using solid particles, instead of detergent. Traditionally, it is said that water and oil do not mix. Until recently, detergent was added to mix oil and water for dispersion. Emulsions have traditionally been produced using this technique and are currently used for products such as mayonnaise, sun block, and lotion.
On the other hand, Pickering emulsions have been used after stabilization of chemical treatments on solid particle surfaces to enhance adsorption power. However, there were limitations in its application, since the treatment process is complex and its applicable range remains limited. Instead of chemical treatment on Pickering emulsion surfaces, the research team mixed small macromolecules a few nanometer in size with larger solid particles (tens of nanometers to a few micrometers). This induced depletion force was used to successfully stabilize the emulsion.
Depletion force refers to the force a large number of small particles induces to aggregate the bigger particles, in order to secure free space for themselves. In short, the force induces an attraction between larger particles. Until now, depletion force could only be applied to solids and solid particles. However, the research team used macromolecules and large particles such as solid particles and oil droplets to show the applicability of depletion force between solids and liquids. By introducing macromolecules that act as smaller particles, hydrophilic solid particles enhanced the adsorption of solid particles to the oil droplet surface, while preventing dissociation from the particle surface, resulting in the maintenance of a stable state.
The research team confirmed the possibility of the simple production of various porous macromolecular materials using stable Pickering emulsions. Such porous macromolecules are expected to be applicable in separation film, systems engineering, drug delivery, and sensors, given their large surface area.
Professor KyuHan Kim, the first author said, “Until now, depletion force has only been used between solid colloid particles. This research has scientific significance since it is the first example of using depletion force between solid particles and liquid droplets.”
Professor Choi said, “Beyond its academic significance, this technology could contribute to industries and national competitiveness.” He continued, “Since this technology uses physical force, not chemical, to produce stable emulsion, it can be used regardless of the type of solid particle and macromolecule. Further, it could be used in customized porous material production for special purposes.”
The research was published in Nature Communications online on February 1. In particular, this research is significant since an undergraduate student, Subeen Kim, participated in the project as a second author through the KAIST Undergraduate Research Program (URP). This research was funded by the National Research Foundation of Korea.
(Figure 1: Images of the inner structure of porous macromolecules produced using the new technology)
(Figure 2: Images showing the measurement of rheological properties of Pickering emulsions and system processability)
(Figure 3: Images showing a stable Pickering emulsion system)
2017.04.19 View 8163 -
2017 Summer Nuclear Nonproliferation Education Program
The Nuclear Nonproliferation Education and Research Center (NEREC) at KAIST announced its 30 scholarship recipients for the 2017 Summer Nuclear Nonproliferation Education Program on April 18. The six-week program, starting from July 10, will be run in Korea, Japan, and China.
The program provides young global scholars with focused and challenging nuclear nonproliferation studies. Young scholars will be exposed to diverse science and technology policies and practices concurrently conducted in many countries and the future direction for enhancing nuclear nonproliferation. They will participate in a series of seminars, projects, international conferences, and field trips.
Since its launch in 2014, the program has educated 71 young scholars. This year, more than 150 scholars from 37 countries applied for the program, reflecting the growing reputation of the program both at home and abroad. The director of the NEREC, Professor Man-Sung Yim of the Department of Nuclear and Quantum Engineering at KAIST said that young scholars from very prestigious foreign universities have shown strong interest in the program. According to Professor Yim, this year’s recipients are from 26 universities from 16 countries including Harvard University, Oxford University, the National Research Nuclear University of Russia, and the Tokyo Institute of Technology
2017.04.19 View 6892 -
Newdin Contents Donates 'Strikezon'
Newdin Contents, an online and mobile game maker, made a gift of ‘Strikezon' to KAIST on April 19. The screen game valued at 100 million KRW will be placed in the lobby of the School of Computing, enriching the diverse physical activity options for the KAIST community. The donation was made at a ceremony attended by KAIST President Sung-Chul Shin, the CEO of the Newdin, Hyo-Kyum Kim, and Head of the School of Computing Professor Myoung Ho Kim.
At the Strikezon, students can enjoy mini baseball games indoors including a batting challenge and a pitching mode indoors for free.
President Shin thanked Mr. Kim of Newdin Contents, saying the donation will be a stepping stone for possible mutual collaborations which will play a synergistic role for technological development. Mr. Kim noted, “We are very pleased to donate the program to KAIST, which is the alma mater of Joon-Mo Hwang, the developer of Strikezon.” He added that Newdin Contents will make every effort to produce advanced game products with state of the art technology.
(Photo caption:President Sung-Chul Shin hits the ball at the Strikezon on April 19.)
2017.04.19 View 4152 -
Scholarship in Memory of Professor Shin Endowed by His Family
Professor Joong-Hoon Shin of the Graduate School of Nanoscience and Technology was touted as a genius young scientist who would take the lead in nanoscience technology. After earning degrees from Harvard and the Caltech, he was appointed at KAIST at age 27. He was the youngest professor ever appointed in Korea.
Professor Shin’s outstanding research in the field of semiconductor nano-optics led him to be named as the ‘Scientist of the Year’ for three consecutive years from 2004 by the most prestigious scientist and technology organizations including the Korean Academy Science and Technology, the National Research Foundation of Korea, and the Korean government. However, a fatal car accident last September on the way home from a seminar in Gangwon Province took his life and a promising scholar’s research was left unfinished. He was 47 years old.
Mrs. Young-Eun Hong, the widow of the late Professor Shin, made a 100 million KRW gift to KAIST to establish the ‘Joong-Hoon Shin Scholarship’ on April 7. The scholarship will provide financial assistance to outstanding students of physics and nanoscience.
At the donation ceremony attended by President Sung-Chul Shin, Professor Shin’s colleagues and students, and family members, Mrs. Hong said, “My family would like to help young students achieve their dreams on behalf of my husband. I hope students will remember my husband’s passion and dedication toward his studies for a long time. He was a very hard worker.”
Working at KAIST, Professor Shin made significant achievements in field of semiconductor nano-optics, specializing in silicon photonics and silicon nanocrystal structures. In particular, his research team gained attention reproducing the structure of ‘Morpho butterfly’ wings, which produce the same colors from various angles, using external light as a light source without extra power. Their research led to the creation of original technology dubbed the biomimetics reflective display and was published in Nature in 2012.
Professor Shin’s legacy still endures. In February, a research team under Professor Shin-Hyun Kim of the Department of Chemical and Biomolecular Engineering includingthe late Professor Shin’s doctoral student Seung Yeol Lee, posthumously dedicated their research published on Advanced Materials to Professor Shin. ( click )
KAIST President Sung-Chul Shin, who is also a physicist, said “His passing is a great loss to the whole scientific and technology community, at home and abroad. But Joong-Hoon Shin scholarship will enable the growth and ensure the strength of nanoscience and its education at KAIST. We will uphold Professor Shin’s legacy by doing our best to make KAIST a world-leading university which can create global value.”
Mrs. Hong said she will continue her husband’s academic legacy at his alma maters, Harvard and the Caltech, where he earned his BS in physics and his Ph.D. in applied physics respectively. She said she will start fundraising to establish the Joong-Hoon Shin Scholarship at Harvard and Caltech from July.
(Mrs. Hong poses with President Sung-Chul Shin after donating 100 million KRW for establishing 'Joong-Hoon Shin Scholarship' in memory of her husband on April 7.)
2017.04.10 View 6791 -
Professor Won Do Heo Receives 'Scientist of the Month Award'
Professor Won Do Heo of the Department of Biological Sciences was selected as the “Scientist of the Month” for April 2017 by the Ministry of Science, ICT and Future Planning and the National Research Foundation of Korea.
Professor Heo was recognized for his suggestion of a new biological research method developing various optogenetics technology which controls cell function by using light. He developed the technology using lasers or LED light, without the need for surgery or drug administration, to identify the cause of diseases related to calcium ions such as Alzheimer’s disease and cancer.
The general technique used in optogenetics, that control cells in the body with light, is the simple activation and deactivation of neurons.
Professor Heo developed a calcium ion channel activation technique (OptoSTIM1) to activate calcium ions in the body using light. He also succeeded in increasing calcium concentrations with light to enhance the memory capacity of mice two-fold.
Using this technology, the desired amount and residing time of calcium ion influx can be controlled by changing light intensity and exposure periods, enabling the function of a single cell or various cells in animal tissue to be controlled remotely.
The experimental results showed that calcium ion influx can be activated in cells that are affected by calcium ions, such as normal cells, cancer cells, and human embryonic stem cells. By controlling calcium concentrations with light, it is possible to control biological phenomena, such as cellular growth, neurotransmitter transmission, muscle contraction, and hormone control.
Professor Heo said, “Until now, it was standard to use optogenetics to activate neurons using channelrhodopsin. The development of this new optogenetic technique using calcium ion channel activation can be applied to various biological studies, as well as become an essential research technique in neurobiology.
The “Scientist of the Month Award” is given every month to one researcher who made significant contributions to the advancement of science and technology with their outstanding research achievement. The awardee will receive prize money of ten million won.
2017.04.07 View 7266 -
Improving Silver Nanowires for FTCEs with Flash Light Interactions
Flexible transparent conducting electrodes (FTCEs) are an essential element of flexible optoelectronics for next-generation wearable displays, augmented reality (AR), and the Internet of Things (IoTs). Silver nanowires (Ag NWs) have received a great deal of attention as future FTCEs due to their great flexibility, material stability, and large-scale productivity. Despite these advantages, Ag NWs have drawbacks such as high wire-to-wire contact resistance and poor adhesion to substrates, resulting in severe power consumption and the delamination of FTCEs.
A research team led by Professor Keon Jae Lee of the Materials Science and Engineering Department at KAIST and Dr. Hong-Jin Park from BSP Inc., has developed high-performance Ag NWs (sheet resistance ~ 5 Ω/sq, transmittance 90 % at λ = 550 nm) with strong adhesion on plastic (interfacial energy of 30.7 J∙m-2) using flash light-material interactions.
The broad ultraviolet (UV) spectrum of a flash light enables the localized heating at the junctions of nanowires (NWs), which results in the fast and complete welding of Ag NWs. Consequently, the Ag NWs demonstrate six times higher conductivity than that of the pristine NWs. In addition, the near-infrared (NIR) of the flash lamp melted the interface between the Ag NWs and a polyethylene terephthalate (PET) substrate, dramatically enhancing the adhesion force of the Ag NWs to the PET by 310 %.
Professor Lee said, “Light interaction with nanomaterials is an important field for future flexible electronics since it can overcome thermal limit of plastics, and we are currently expanding our research into light-inorganic interactions.”
Meanwhile, BSP Inc., a laser manufacturing company and a collaborator of this work, has launched new flash lamp equipment for flexible applications based on the Professor Lee’s research.
The results of this work entitled “Flash-Induced Self-Limited Plasmonic Welding of Ag NW Network for Transparent Flexible Energy Harvester (DOI: 10.1002/adma.201603473)” were published in the February 2, 2017 issue of Advanced Materials as the cover article.
Professor Lee also contributed an invited review in the same journal of the April 3, 2017 online issue, “Laser-Material Interactions for Flexible Applications (DOI:10.1002/adma.201606586),” overviewing the recent advances in light interactions with flexible nanomaterials.
References
[1] Advanced Materials, February 2, 2017, Flash-Induced Self-Limited Plasmonic Welding of Ag NW network for Transparent Flexible Energy Harvester http://onlinelibrary.wiley.com/doi/10.1002/adma.201603473/epdf
[2] Advanced Materials, April 3, 2017, Laser-Material Interactions for Flexible Applications
http://onlinelibrary.wiley.com/doi/10.1002/adma.201606586/abstract
For further inquiries on research:
keonlee@kaist.ac.kr (Keon Jae Lee), hjpark@bsptech.co.kr (Hong-Jin Park)
Picture 1: Artistic Rendtition of Light Interaction with Nanomaterials
(This image shows flash-induced plasmonic interactions with nanowires to improve silver nanowires (Ag NWs).)
Picture 2: Ag NW/PET Film
(This picture shows the Ag NWs on a polyethylene terephthalate (PET) film after the flash-induced plasmonic thermal process.)
2017.04.05 View 9489 -
A Transport Technology for Nanowires Thermally Treated at 700 Celsius Degrees
Professor Jun-Bo Yoon and his research team of the Department of Electrical Engineering at KAIST developed a technology for transporting thermally treated nanowires to a flexible substrate and created a high performance device for collecting flexible energy by using the new technology.
Mr. Min-Ho Seo, a Ph.D. candidate, participated in this study as the first author. The results were published online on January 30th in ACS Nano, an international journal in the field of nanoscience and engineering. (“Versatile Transfer of an Ultralong and Seamless Nanowire Array Crystallized at High Temperature for Use in High-performance Flexible Devices,” DOI: 10.1021/acsnano.6b06842)
Nanowires are one of the most representative nanomaterials. They have wire structures with dimensions in nanometers. The nanowires are widely used in the scientific and engineering fields due to their prominent physical and chemical properties that depend on a one-dimensional structure, and their high applicability.
Nanowires have much higher performance if their structure has unique features such as an excellent arrangement and a longer-than-average length. Many researchers are thus actively participating in the research for making nanowires without much difficulty, analyzing them, and developing them for high performance application devices.
Scientists have recently favored a research topic on making nanowires chemically and physically on a flexible substrate and applies the nanowires to a flexible electric device such as a high performance wearable sensor.
The existing technology, however, mixed nanowires from a chemical synthesis with a solution and spread the mixture on a flexible substrate. The resultant distribution was random, and it was difficult to produce a high performance device based on the structural advantages of nanowires. In addition, the technology used a cutting edge nano-process and flexible materials, but this was not economically beneficial. The production of stable materials at a temperature of 700 Celsius degrees or higher is unattainable, a great challenge for the application.
To solve this problem, the research team developed a new nano-transfer technology that combines a silicon nano-grating board with a large surface area and a nano-sacrificial layer process. A nano-sacrificial layer exists between nanowires and a nano-grating board, which acts as the mold for the nano-transfer. The new technology allows the device undergo thermal treatment. After this, the layer disappears when the nanowires are transported to a flexible substrate.
This technology also permits the stable production of nanowires with secured properties at an extremely high temperature. In this case, the nanowires are neatly organized on a flexible substrate. The research team used the technology to manufacture barium carbonate nanowires on top of the flexible substrate. The wires secured their properties at a temperature of 700℃ or above. The team employed the collection of wearable energy to obtain much higher electrical energy than that of an energy collecting device designed based on regular barium titanate nanowires.
The researchers said that their technology is built upon a semiconductor process, known as Physical Vapor Deposition that allows various materials such as ceramics and semiconductors to be used for flexible substrates of nanowires. They expected that high performance flexible electric devices such as flexible transistors and thermoelectric elements can be produced with this method.
Mr. Seo said, “In this study, we transported nanowire materials with developed properties on a flexible substrate and showed an increase in device performance. Our technology will be fundamental to the production of various nanowires on a flexible substrate as well as the feasibility of making high performance wearable electric devices.”
This research was supported by the Leap Research Support Program of the National Research Foundation of Korea.
Fig. 1. Transcription process of new, developed nanowires (a) and a fundamental mimetic diagram of a nano-sacrificial layer (b)
Fig. 2. Transcription results from using gold (AU) nanowires. The categories of the results were (a) optical images, (b) physical signals, (c) cross-sectional images from a scanning electron microscope (SEM), and (d-f) an electric verification of whether the perfectly arranged nanowires were made on a large surface.
Fig. 3. Transcription from using barium titanate (BaTiO3) nanowires. The results were (a) optical images, (b-e) top images taken from an SEM in various locations, and (f, g) property analysis.
Fig. 4. Mimetic diagram of the energy collecting device from using a BaTiO3 nanowire substrate and an optical image of the experiment for the miniature energy collecting device attached to an index finger.
2017.03.22 View 8356 -
Professor Kwangjo Kim Named as Fellow of IACR
Professor Kwangjo Kim of the Graduate School of Information Security has been selected as a fellow of the International Association for Cryptologic Research (IACR).
The IACR has honored outstanding scholars who have achieved academic excellence in cryptologic research since 2004. He is the first Korean scholar to receive an IACR fellowship.
The IACR, established in 1981, is responsible for organizing international cryptologic conferences every year including the three major cryptologic academic conferences Eurocrypt, Crypto, and Asiacript. The IACR also sponsors workshop series such as the Theory of Cryptography Conference (TCC), the Workshop on Fast Software Encryption (FSE), the Public Key Cryptography Workshop (PKC), and Cryptographic Hardware and Embedded Systems (CHES).
Professor Kim, an internationally acclaimed scholar in the fields of cryptology and information security theory and its applications, was recognized for his outstanding academic achievements and leadership. He has made significant contributions to cryptology in Korea by hosting Asiacript in 1996 and 2001 as well as CHES in 2014. During his 34 years of academic activities, he has published more than 80 SCI journal papers and garnered more than 20,000 citations.
Professor Kim served on the board of the directors of the IACR from 2000 to 2004 and was the chairperson of the Asiacript Steering Committee from 2005 to 2008. He is on the editorial board of the online journal Cryptography.
Professor Kim said, “I am so humbled and honored to be named as a fellow of such a prestigious academic association. I will continue to strive to assist highly educated information security personnel with further research in cryptology.”
2017.03.16 View 6964 -
Global Workshop on the Risks of Emerging Technologies
The Center for Science, Policy and Society (CSPS) at the Graduate School of Science and Technology Policy of KAIST will host the 2017 Global Expert Workshop on the Risks of Emerging Technologies Driving the Fourth Industrial Revolution March 17-18 at the Plaza Hotel in Seoul.
At the workshop, experts from public and private sectors at home and abroad will address the socio-economic impacts and implications of the emergence of new technologies that the Fourth Industrial Revolution will bring about. The workshop will be hosted in collaboration with the World Economic Forum’s Global Future Council (GFC) on Technology, Values and Policy. The World Economic Forum’s network of GFCs is the world’s foremost interdisciplinary knowledge network dedicated to promoting innovative thinking about the future.
Four keynote speakers, including Professor Wendell Wallach of the Interdisciplinary Center for Bioethics at Yale University and Dean of the School of Public Policy and Management at Tsinghua University Lan Xue, will deliver speeches. Professor Wallach is the leader of an AI/Robotics Global Governance Project sponsored by the World Economic Forum and will make a speech entitled “Build the Global Infrastructure to Make Sure that AI and Robotics Will Be Beneficial.” Dean Xue, a member of the World Economic Forum’s GFC on Tech, Values, and Policy, is well known for his analysis of the social implications of the risks brought about by emerging technologies. He will speak on “Global Risk Governance of Disruptive 4IR Technologies.”
More than thirty experts will participate in the workshop. Speakers include the KAIST Vice President for Planning and Budget Soohyun Kim, Dean of KAIST Institute San Yup Lee, Professor Jaeseung Jeong of the Department of Bio and Brain Engineering at KAIST, Dr. Sung Chul Kang of the KIST Healthcare Robotics Research Group, and Korea Evaluation Institute of Industrial Technology Program Director Kyong Hoon Kim.
The CSPS of KAIST will continue to make collaborative research efforts with the GFC for developing new insights and perspectives on key global systems as well as study the impact and governance of key emerging technologies.
2017.03.16 View 8501 -
Dr.Sung-Chul Shin Inaugurated as the 16th President of KAIST
(President Shin delivers his inaugural address at the inauguration ceremony on March 15.)
Professor Sung-Chul Shin was officially inaugurated as its 16th president of KAIST on March 15 in a ceremony at the KAIST Auditorium.
The celebration began with a procession by dignitaries including the KAIST Board of Trustees Chairman Jang-Moo Lee, the National Academy of Sciences of Korea President Sook-Il Kwun, Daejeon City Mayor Sun-Taik Kwon, National Assemblyman Sangmin Lee, KAIST Alumni Association President Jungsik Koh. Academic leaders, foreign envoys, faculty, students, and staff members of KAIST joined the ceremony.
In his inaugural speech, President Shin presented a new vision for KAIST to become a global value creator in the Fourth Industrial Revolution. He said that KAIST has played a pivotal role in the nation’s industrialization and information revolution over the past half century and, with the advent of the new industry paradigm, KAIST should be now responsible for being a new value creator, not only serving the nation but pursuing global betterment. “KAIST should be a global hub of new knowledge and technology creation,” he emphasized.
Envisioning a “Global Value-Creative World-Leading University,” President Shin aims for KAIST to be an institution which can create global value as an innovative global leading research university. To realize this vision, he pledged to continue innovation in five areas of education, research & development, technology commercialization, globalization of the campus, and future strategy for the university and the nation.
In the educational innovation, he emphasized multidisciplinary studies, team work, and leadership training for students. To this end, KAIST will expand the non-departmental courses toward entire 4-year course while concurrently operating the existing system of declaring a major in students’ second year. KAIST will offer mandatory courses in humanities, social sciences, and arts and most classes will be run by team-based learning and group research activities. “KAIST Global Leadership Center” will support students to develop the qualities required for collaboration and the global leaderships.
With respect to the research innovation, President Shin said KAIST will establish “Convergence Research Matrix” system to foster strategic research groups for interdisciplinary and convergence collaboration across a wide range of divisions and departments. “Based on the CRMS, we will identify 10 flagship future-oriented convergence research areas for KAIST to truly claim its reputation as a world-leading research university,” he said. He added he will also introduce the “Collaborative Research Lab” system to better retain the academic successes without interruption, and to improve the continuity of research. “We will strive to organize teams of professors in diverse age groups to work together in mutually complementary fields,” he added.
In terms of technological commercialization, he hopes that KAIST to be a role model. He said he will make every effort to establish a resilient R&DB environment with ideas, technologies, and entrepreneurship. KAIST will rev up a new university-industry cooperation, fully sponsoring the creation of “Technology in-Kind Investment Companies.”
KAIST will continue to take initiative for globalization. He said KAIST will create an ‘English-Only Zone’ at the campus, saying that his ultimate goal is to create Korean-English bilingual campus. He also asked the foreign community to make their effort to learn Korean and Korean culture while staying at KAIST, in an effort to embrace diversity at the campus. He plans to increase the ratio of foreign faculty from nine percent to 15 percent, while doubling the current foreign student enrollment ratio of five percent.
As for the future strategy for the university and the nation, he will soon finalize the long-term strategic plan of “Vision 2031” that will lay out a roadmap for KAIST future direction toward its 60th anniversary. KAIST will also play a fundamental role in shaping national policies and strategies for science and technology by operating think-tank groups that consist of KAIST beyond disciplines. These think-tanks will design detailed development plans for KAIST as well as for national strategies for the advancement of science and technology.
He said that such institutional innovation will not be completed without the support, dedication, and passion of all KAIST members, adding that he will strive to serve them with 3Cs (Change, Communication, and Care).
For the full text of President Shin’s inaugural address, please click.
2017.03.15 View 9230 -
Highly-Efficient Photoelectrochemical CO2 Reduction
Direct CO2 conversion has continuously attracted a great deal of attention as a technology to produce fuels and chemical building blocks from renewable energy resources. Specifically, substances such as carbon feedstocks and fuels can be produced by utilizing sunlight, water, and CO2 as semiconductors and a water interface through photoelectrochemical CO2 reduction.
A KAIST research team demonstrated a novel photoelectrode structure for highly-selective and efficient photoelectrochemical CO2 reduction reactions. The research team led by Professor Jihun Oh of the Graduate School of EEWS (Energy, Environment, Water and Sustainability) presented a Si photoelectrode with a nanoporous Au thin film that is capable of reducing CO2 to CO with 90 percent selectivity in aqueous solution. The research team’s technology will provide a basic framework for designing the semiconductor photoelectrode structure necessary for photoelectrochemical conversion.
In order to achieve steady conversion of CO2, it is necessary to use a high-performance catalyst to lower overpotential. Among the metal catalysts, Au is known to be an electrocatalyst that converts CO2 to CO.
Conventionally, bare Au, as a catalyst, produces a lot of hydrogen gas due to its low CO selectivity. In addition, the high cost of Au remains a challenge in using the catalyst. Professor Oh’s research team addressed the issue by creating a nanoporous Au thin film formed by the electrochemical reduction of an anodized Au thin film.
As a result, the team could demonstrate an efficient, selective photoelectrochemical reduction reaction of CO2 to CO using electrochemically-treated Au thin films on a Si photoelectrode. The electrochemical reduction on anodized Au thin films forms a nanoporous thin layer exhibiting many grain boundaries of nanoparticles on the Au surface. This dramatically improves the selectivity of the reduction reaction with a maximum CO faradaic efficiency of over 90% at low overpotential and durability.
The research team also used an Au thin film of about 200 nanometers, 50,000 times thinner than previously reported nanostructured Au catalysts, resulting in a cost-effective catalyst. When depositing the catalyst on the semiconductor surface in the type of nanoparticles, the substrate of the thin film will be affected in the course of electrochemical reduction.
Thus, the research team designed a new Si photoelectrode with mesh-type co-catalysts that are independently wired at the front and back of the photoelectrode without influencing the photoelectrode, and made it possible for electrochemical reduction.
Due to the superior CO2 reduction reaction activity of the nanoporous Au mesh and high photovoltage from Si, the Si photoelectrode with the nanoporous Au thin film mesh shows conversion of CO2 to CO with 91% Faradaic efficiency at positive potential than CO equilibrium potential.
Professor Oh explained, “This technology will serve as a platform for diverse semiconductors and catalysts. Researchers can further improve the solar-to-CO2 conversion efficiency using this technology.
Dr. Jun Tae Song, the first author continued, “This new approach made it possible to develop a simple but very important type of electrode structure. It is the first time to achieve CO2 conversion at the potential lower than equilibrium potential. We believe that our research will contribute to efficient CO2 conversion.”
This research was published in the inside front cover of Advanced Energy Materials on February 8, 2017. The research was funded and supported by the Korea Carbon Capture & Sequestration R&D Center. Professor Sung-Yoon Chung of the EEWS also participated in this research.
(Figure: Schematic diagram of a Si photoelectrode that patterns with mesh-type nanoporous Au)
2017.03.08 View 9078 -
13 KAIST Faculty Named as Inaugural Members of Y-KAST
The Korean Academy of Science and Technology (KAST) launched the Young Korean Academy of Science and Technology (Y-KAST) and selected 73 scientists as its inaugural members on February 24. Among them, 13 KAIST faculty were recognized as the inaugural members of Y-KAST.
Y-KAIST, made up of distinguished mid-career scientists under the age of 45, will take the leading role in international collaboration as well as innovative agenda-making in science and technology.
The inaugural members include Professor Hyotcherl Ihee of the Department of Chemistry and Dr. Sung-Jin Oh of the Center for Mathematical Challenges at the Korea Institute for Advanced Study (KIAS), affiliated with KAIST. Professor Ihee is gaining wide acclaim in the fields of physics and chemistry, and in 2016, Dr. Oh was the youngest ever awardee of the Presidential Award of Young Scientist.
The other Y-KAIST members are as follows: Professors Haeshin Lee of the Department of Chemistry; Mi Young Kim, Byung-Kwan Cho, and Ji-Joon Song of the Department of Biological Sciences; Song-Yong Kim of the Department of Mechanical Engineering; Sang-il Oum of the Department of Mathematical Sciences; Jung Kyoon Choi of the Department of Bio and Brain Engineering; Seokwoo Jeon, Sang Ouk Kim, and Il-Doo Kim of the Department of Materials Science and Engineering; Jang Wook Choi of the Graduate School of EEWS (Energy, Environment, Water and Sustainability); and Jeong Ho Lee of the Graduate School of Medical Science and Engineering.
The leading countries of the Academy of Science, which include Germany, Sweden, Belgium, Canada, and Japan, have established the Young Academy of Science since 2010 in order to encourage the research activities of their young scientists and to establish a global platform for collaborative research projects through their active networking at home and abroad.
President Myung-Chul Lee of KAST said, “We will spare no effort to connect these outstanding mid-career researchers for their future collaboration. Their networking will make significant impacts toward their own research activities as well as the global stature of Korea’s science and technology R&D.
(Photo caption: Members of Y-KAST pose at the inaugural ceremony of Y-KAST on February 24.)
2017.03.02 View 15301