Faculty

Engineering researchers are putting an innovative two-story structure made of cross-laminated timber (CLT) panels through a series of seismic tests to gather scientific data that will enable design of mass timber buildings that can survive large earthquakes with little or no repair.

Colorado School of Mines Civil and Environmental Engineering Assistant Professor Shiling Pei is the lead researcher on the NSF-funded project, having conducted similar tests on a much smaller scale on Mines’ campus prior to this massive effort using the world’s largest outdoor shake-table in San Diego, California.

“Designing buildings that are safe even during large earthquakes is hugely important. We are doing that – and we are going further,” Pei said. “We are working to minimize the amount of time buildings are out of service after large earthquakes. We are also focused on cutting the costs required to repair them.”

The tests are being conducted at NHERI@UCSD, an experimental test site at UC San Diego funded through the NSF’s Natural Hazard Engineering Research Infrastructure (NHERI) program. The tests will produce data that will be used in the design of a new generation of tall mass timber structures up to 20 stories.

Researchers work on compeleting construction of the test-structure. Photo Credit: University of California San Diego Jacobs School of Engineering
Researchers work on compeleting construction of the test-structure.
Photo Credit: University of California San Diego Jacobs School of Engineering

“The overarching goal of this project is to propose a design methodology for seismically resilient tall wood buildings for regions with high seismicity, meaning the building can be quickly repaired after large earthquakes to minimize loss of use,” Pei said. “Several tests will be conducted at different shaking intensities representing frequent, design code level and maximum considered earthquake events.”

The 22-foot-tall structure will be put through a tremor simulating the 6.7 magnitude 1994 Northridge earthquake in the San Fernando Valley, but for twice as long. Researchers will collect data through more than 300 channels in three phases of testing on the building. Data will be generated at pre-selected points to measure how the CLT panels bend and how the panels move relative to each other.

Researchers are particularly interested in a system that allows the building to rock in response to an earthquake and how the walls and floors interact during shaking.

“We have tested the rocking walls by themselves in the lab, but as structural engineers, we know that the system is not equal to the sum of its parts. There are interactions between the parts. That’s why NHERI projects funded by the NSF are so critical. We are finally going to be able to get data on how the different components function as a system during strong earthquakes,” Pei said. 

In a so-called “rocking wall system,” vertical mass timber walls are connected to the foundation by post-tensioned rods that run up through the floor and special U-shaped steel energy dissipaters. The rods allow the walls to rock during an earthquake and snap back into their original upright position, minimizing deformation and resulting structural damage.

A consortium of universities is collaborating on the NSF project, including Mines, Colorado State University, University of Washington, Washington State University, Oregon State University, Lehigh University, University of Nevada Reno and University of California San Diego.

The two-story investigative testing also received support from multiple industrial partners including Katerra; Simpson Strong-Tie; Tallwood Design Institute; DR Johnson Lumber Co.; Forest Products Laboratory; City of Springfield, Oregon; Softwood Lumber Board; and MyTiCon Timber Connectors.

The NSF project also includes another large-scale test planned later this year at the NHERI-Lehigh testing facility. Based on the insights gleaned from this current set of tests and related research, the team will return to San Diego in 2020 to build, shake and ultimately burn an earthquake-resilient 10-story timber building on the UC San Diego shake table.

The project detail can be found on http://nheritallwood.mines.edu. Ongoing activity at the outdoor shake-table of the Natural Hazards Engineering Research Infrastructure facility is live-streamed by webcam at http://nees.ucsd.edu/video/.  Photos are available on Flickr at http://bit.ly/Shake714.

Contact:
Agata Bogucka, Communications Manager, College of Earth Resource Sciences & Engineering | 303-384-2657 | abogucka@mines.edu
Emilie Rusch, Public Information Specialist | 303-273-3361 | erusch@mines.edu

Colorado School of Mines Civil and Environmental Engineering Professor Marte Gutierrez, Petroleum Engineering Professor Azra Tutuncu and alumnus Luke Frash have been awarded the 2017 Applied Rock Mechanics Research Award by the American Rock Mechanics Association.


Luke Frash and Marte Gutierrez during a visit with Darren Mollot, Director of the Office of Clean Energy Systems in the Department of Energy’s (DOE) Office of Fossil Energy.
Luke Frash and Marte Gutierrez showcase their research during a visit from Darren Mollot, Director of the Office of Clean Energy Systems in the Department of Energy’s (DOE) Office of Fossil Energy.

Frash earned bachelor’s and master’s degrees in engineering with specialties in civil engineering and a PhD in civil and environmental engineering from Mines, studying under Gutierrez. He is now a researcher at Los Alamos National Laboratory in New Mexico.

The team is receiving the award for their 2015 publication, “True-Triaxial Hydraulic Fracturing of Niobrara Carbonate Rock as an Analogue for Complex Oil and Gas Reservoir Stimulation.” The main topics of research, funded partially by the U.S. Department of Energy and the Unconventional Natural Gas and Oil Institute, were development of enhanced geothermal systems and hydraulic fracturing in shale oil and gas reservoirs.

“Well stimulation by hydraulic fracturing is a common method for increasing the injectivity and productivity of wells,” Gutierrez said. “This method is beneficial for many applications, including oil, gas, geothermal energy and CO2 sequestration; however, hydraulic fracturing in shale and other similarly complex geologies remains poorly understood.”

Seeking to bridge the gap in understanding, the team conducted research on large natural rock specimens using true-triaxal stresses, intended to represent field-scale complexities of known oil and gas reservoirs.

“Results from such large-scale hydraulic experiments, particularly on naturally heterogeneous rock samples, remain very limited,” Gutierrez said.

The research team developed special equipment to conduct these innovative field-scale experiments, and Gutierrez says “the results from the scale-model hydraulic fracturing experiments are envisioned to be of important value to the practice of hydraulic fracturing in several fields.”

The award will be presented during the 51st U.S. Rock Mechanics/Geomechanics Symposium in San Francisco, California, on June 25-28, 2017.

Support for the research was provided by the Unconventional Natural Gas and Oil Institute (UNGI) Coupled Integrated Multi Scale Measurements and Modeling Consortium (CIMMM), and the U.S. Department of Energy under DOE Grant No. DE-FE0002760, “Development and Validation of an Advanced Stimulation Prediction Model for Enhanced Geothermal Systems.”

Contact:
Agata Bogucka, Communications Manager, College of Earth Resource Sciences & Engineering | 303-384-2657 | abogucka@mines.edu
Mark Ramirez, Managing Editor, Communications and Marketing | 303-273-3088 | ramirez@mines.edu

Amadeu Sum, associate professor of chemical and biological engineering, has been awarded the 2017 Arthur Lubinski OTC Best Paper Award by the American Society of Mechanical Engineers (ASME).

This prestigious recognition is awarded annually during the Offshore Technology Conference (OTC) by the ASME Petroleum Division to a contribution that has the highest impact on the offshore industry. The award is named after Arthur Lubinski, who created the ASME Study Committee for the Exchange of Offshore Information that led to the formation of OTC.


Greg Kusinski, Amadeu Sum, Joseph Gomes
From left to right: Greg Kusinski, Amadeu Sum, Joseph Gomes receive the award at the OTC2017 ASME Banquet.

Sum received the award for his paper “Hydrate Management for Systems with High Salinity Brines at Ultra-High Pressures,” coauthored with Yue Hu and Bo Ram Lee, Colorado School of Mines; Prasad Karanjkar, ConocoPhillips; Joseph Gomes, DeepStar; and Greg Kusinski, Chevron. This paper was selected from the hundreds of submissions that were presented at OTC2017 in Houston, Texas.

The work was inspired by an engineering challenge initiated by DeepStar, a joint industry technology development consortium of 12 oil and gas companies, seeking to support deepwater high-pressure, high-temperature (HPHT) field development activities in the Gulf of Mexico.

In order to conduct research in these extreme conditions, the research team engineered a novel HPHT experimental chamber in which a series of experiments was conducted. This work enabled the delivery of a computational model that can serve as a practical engineering tool for Industry to better predict undesired hydrate plug formations, allowing for optimization of methanol treatment.

Sum’s work verified and validated industry’s understanding of thermodynamics relative to hydrate formation in high salinity and HPHT systems, proving fundamentally important to the development of HPHT fields.

The Lubinski Best Paper Award was presented to Sum and his coauthors on May 1 at the ASME Best Mechanical Engineering Award Banquet.

Contact:
Agata Bogucka, Communications Manager, College of Earth Resource Sciences & Engineering | 303-384-2657 | abogucka@mines.edu
Mark Ramirez, Managing Editor, Communications and Marketing | 303-273-3088 | ramirez@mines.edu
 

Andrew Petruska, assistant professor of mechanical engineering at Colorado School of Mines, has been selected to receive the Boettcher Foundation’s Webb-Waring Biomedical Research Award. Petruska is one of nine biomedical researchers at Colorado’s top institutions selected to receive funding. Recipients are awarded $235,000 in grant funding to sustain three years of biomedical research.

Petruska’s research looks to develop a system that actively steers neurosurgical electrodes to target locations deep within the brain along nonlinear paths. Neurosurgical electrode placement is performed to treat a range of conditions, from Parkinson’s disease to chronic pain to epilepsy.

Current procedures rely on stiff instruments, which can only insert the electrodes in a straight line, making it very difficult for a neurosurgeon to curve around critical structures in the brain or adjust the trajectory to correct for minor errors. Petruska aims to create a system with novel architecture that actively steers a flexible magnetic instrument to its target.

This system has the potential to reduce invasiveness of the procedure by having one main insertion path, enhance safety by allowing the clinician to bend around sensitive structures and enable trajectories that allow a multi-contact electrode to target multiple structures.

In its eighth year, the Webb-Waring award supports promising early-career scientific researchers with funding and the title of Boettcher Investigator. Since its founding, 54 Boettcher Investigators at the state’s leading academic and research institutions have received funding through the program.

Contact:
Anica Wong, Communications Specialist, Colorado School of Mines Foundation | 303-273-3904 | acwong@mines.edu
Mark Ramirez, Managing Editor, Communications and Marketing | 303-273-3088 | ramirez@mines.edu

Student Life award winners from left to right: Rob Thompson, Lisa Goberis, Deb Roberge, Isabelle Jeffries, Emilie Nemchak and Amanda Davis.

The Division of Student Life recognized exceptional staff and programs at its annual awards presentation at Marv Kay Stadium on June 7, 2017.

The Student Life Annual Awards luncheon highlights top performers who are nominated by their peers. More than 50 nominations were submitted for five award categories. The submissions were reviewed by a committee that presented the winners with their awards at the event.

  • New Oredigger Award: Amanda Davis, Academic Advising Coordinator
  • Oredigger Community Spirit Award: Rob Thompson, Assistant Athletic Director/Director of Student Recreation Center
  • Unsung Hero Award: Lisa Goberis, Director of Student Life Business Administration
  • Outstanding Student Life Employee Award: Deb Roberge, Director of the Coulter Student Health Center
  • Outstanding Program/Service Award: Helluva Service Event represented by Isabelle Jeffries, Coordinator of Greek Life, and Emilie Nemchak, Residence Life Coordinator

“Congratulations to all of our nominees and award winners,” said Lia Franklin, executive assistant to the vice president. “You make us proud as a division as we continue to strive for ‘excellence in everything we do.’”

CONTACT
Joe DelNero, Digital Media and Communications Manager, Communications and Marketing | 303-273-3326 | jdelnero@mines.edu
Mark Ramirez, Managing Editor, Communications and Marketing | 303-273-3088 | ramirez@mines.edu

Colorado School of Mines has appointed a dean of graduate studies, who will lead efforts to strengthen research-based graduate programs, increase the university's international student population and promote professional master's and certificate programs.

Wendy Zhou, associate professor of geology and geological engineering, begins her new role at the start of the fall 2017 semester.

“I want to keep our uniqueness, but we need to do something different,” Zhou said. “I believe I have creative ideas that can keep Mines’ uniqueness but can change much needed areas of the graduate education here.”

Zhou’s initiatives will include working to promote professional master’s and certificate programs, increase international graduate student enrollment as well as undertaking a graduate student climate survey that will help Mines develop and implement programs and initiatives that enhance co-curricular support of the research-based residential graduate population.

“I want to feel the heartbeat of the students as a whole,” Zhou said. “The climate survey is part of the way to do that.”

Zhou also wants to hold town hall meetings and graduate student seminars to add opportunities for networking and socializing. In collaboration with Roel Snieder, the newly appointed W.M. Keck Distinguished Professor of Professional Development Education, she will create programs to help students develop professional portfolios.

“I see graduate student quality control as a pipeline,” Zhou said. “We will have quality control from admission to graduation, which will better prepare students for success after graduation.”

Zhou joined the Mines faculty in 2008. She received her PhD in geological engineering from Missouri University of Science and Technology. She has a research group of seven graduate students. Her research is focused on the use of geographic information systems and remote sensing for environmental studies and to assess geohazards such as landslides and ground subsidence.

“I chose Wendy for the dean position because she is passionate about advancing a set of well-defined and institutionally important initiatives,” Interim Provost Tom Boyd said. “We hope to develop and create institution-wide initiatives aimed at providing our graduate students—and the programs in which they reside—the opportunity to further develop their professional skill sets.”

 

CONTACT
Joe DelNero, Digital Media and Communications Manager, Communications and Marketing | 303-273-3326 | jdelnero@mines.edu
Mark Ramirez, Managing Editor, Communications and Marketing | 303-273-3088 | ramirez@mines.edu

A team of Colorado School of Mines researchers has found that the activated carbon filtration systems currently being used to remove highly fluorinated chemicals such as perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) from drinking water are likely not nearly as effective at removing newly discovered poly- and perfluoroalkyl substances (PFASs). 

“It was just over a year ago that the U.S. EPA issued lifetime health advisories for PFOA and PFOS, and while no health advisories have been issued for these related chemicals, they share many of the same characteristics. This study raises important questions about exposure to these compounds, even when carbon filters are being used.” said Chris Higgins, the senior author on the study and an associate professor of civil and environmental engineering at Mines.
 
The results of their study, which was published June 6, 2017, in Environmental Science and Technology, impacts the current efforts that are underway around the United States to remove PFOA and/or PFOS that were found in the drinking water of communities in and around military bases and airports where a firefighting foam containing the contaminants was used. In response, communities installed, or are currently installing, activated carbon filters to remove these two chemicals.

In their study, Mines researchers found that there are numerous related highly fluorinated chemicals also associated with firefighting foam, and that these newly characterized contaminants are likely to pass through filtration systems designed to remove PFOA and PFOS.  “We already know that PFOA and PFOS are linked to a variety of adverse health effects in humans, but health effects data are lacking for most other chemicals in this class.” acknowledged Higgins. The global community is clearly concerned about these other PFASs, as just last week, Norway nominated perfluorohexane sulfonate (PFHxS), one of the PFASs included in the study, to the Stockholm Convention for Persistent Organic Pollutants. In addition to PFHxS itself, at least 20 percent of the newly discovered PFASs that Higgins’ team predicts will break through GAC filters before either PFOS and PFOA are chemical precursors to PFHxS. If ingested, it is likely that they would be transformed to PFHxS in the human body.    

The team that contributed to the study, titled “Sorption of Poly- and Perfluoroalkyl substances (PFASs) relevant to Aqueous Film Forming Foam (AFFF)-impacted Groundwater by Biochars and Activated Carbon,” include Xin Xiao, a visiting scholar from Zhejiang University in China, and his PhD advisor, Baoliang Chen. Xin spent a little over one year at Mines working on the project with Higgins and Bridget Ulrich, a Mines PhD graduate now working at the Swiss Federal Institute of Aquatic Science and Technology.

The study’s publication coincides with the release of an ES&T and ES&T Letters Virtual Issue on PFASs put together by Higgins along with other researchers. 

Contact:
Megan Hanson, Communications Manager, College of Applied Science and Engineering | 303-384-2358 | mhanson@mines.edu
Mark Ramirez, Managing Editor, Communications and Marketing | 303-273-3088 | ramirez@mines.edu

A veteran scientist with the National Renewable Energy Laboratory with two decades of experience in academia has been named the new head of the Department of Chemistry at Colorado School of Mines.

Dr. Thomas Gennett will join Mines after nine years at NREL, in Golden, Colo. For the last two years, he has also served as director of the DOE-EERE Hydrogen Storage Characterization and Optimization Research Effort, or HySCORE, which seeks to discover new materials and investigate the mechanism of room-temperature hydrogen sorption for carbon and framework sorbents as well as develop next-generation characterization methodologies applicable to gas-sorption. HySCORE is a collaboration between several national laboratories.

Gennett’s research interests include hydrogen storage characterization and optimization, fundamental charge transfer processes in stable free-radical organic polymer material systems, non-pgm catalysts and hybrid hard-soft materials for energy storage. Gennett holds a BA in chemistry from the State University of New York at Potsdam and a PhD in Analytical Chemistry from the University of Vermont. He was a professor of chemistry and materials Science at Rochester Institute of Technology for 18 years and holds the title of emeritus.

Gennett officially joines Mines on July 1, taking over for Professor David Wu, who has served as department head since 2012. 

Gennett first came to Mines while on sabbatical at NREL. At that time, he met with Chemistry Professor Dan Knauss, then the department head, and discussed Knauss’ new vision for the department. Gennett joined the NREL staff in 2008. Over the last 20 years, Gennett has had many interactions with Mines, including collaborations with metallurgical and materials engineering faculty Ryan O’Hayre and Corinne Packard and Chemistry Professor Ryan Richards. 

“Dan Knauss had a great vision for this department and definitely started it off on its current trajectory,” said Gennett. “And David Wu has taken in from there. It’s truly amazing the change they were able to institute in the department. They’ve made the Mines Chemistry Department a research leader comparable to any other program, and this is an unbelievable opportunity to now take over one of the most desirable positions in academic chemistry.”

Gennett is already meeting with staff and creating plans for the department.

“The challenges moving forward will be maintaining our top research position while also increasing enrollment,” said Gennett. “We will have a series of meetings in the next months and come up with a departmental plan for the next five years and beyond. The opportunities are there, and we have the faculty to obtain them.” 

Mike Kaufman, dean of the College of Applied Science and Engineering which is home to the Chemistry Department, is excited to have Gennett join Mines. 

“Tom brings great experience to the department and is passionate about working with the faculty, staff in Chemistry and his colleagues across campus to ensure that the positive trajectory set by Professors Knauss and Wu continues,” said Kaufman.

Outside of work, Gennett is an avid runner and the single parent of two girls, ages 10 and 13. He lives in Denver.

Contact:
Megan Hanson, Communications Manager, College of Applied Science and Engineering | 303-384-2358 | mhanson@mines.edu
Mark Ramirez, Managing Editor, Communications and Marketing | 303-273-3088 | ramirez@mines.edu

 

Map of the eastern Indian Ocean and surrounding regions. Location of the drilling expedition and the Sunda subduction zone also shown. The Indo-Australian plate subducts beneath the Eurasian plate at the subduction zone and it was the source of the 2004 earthquake and tsunami offshore Sumatra to Andaman Islands (rupture area shaded in yellow). Ocean drilling boreholes are red dots (U1480, U1481). The Bengal and Nicobar submarine fans are fed by river sediments eroded from the Himalaya and Tibetan Plateau, creating very large thicknesses of sediment. (Credit: Lisa McNeill, University of Southampton.)
Map of the eastern Indian Ocean and surrounding regions. The Indo-Australian that plate was the source of the 2004 Sumatra earthquake and tsunami subducts beneath the Eurasian plate at the subduction zone (rupture area shaded in yellow). Ocean drilling boreholes are red dots (U1480, U1481).  (Credit: Lisa McNeill, University of Southampton.)

An international team of scientists has found evidence suggesting the dehydration of minerals deep below the ocean floor influenced the severity of the Sumatra earthquake, which took place on December 26, 2004, off the west coast of Indonesia.

The magnitude 9.2 earthquake and subsequent tsunami devastated coastal communities of the Indian Ocean, killing over 250,000 people.

Research into the earthquake was conducted during a scientific ocean drilling expedition to the region August through October 2016 as part of the International Ocean Discovery Program (IODP). Expedition 362 was led by researchers from Colorado School of Mines and the University of Southampton in collaboration with IODP scientist Katerina Petronotis.

On board the research vessel JOIDES Resolution, the researchers sampled, for the first time, sediments and rocks from the oceanic tectonic plate that feeds the Sumatra subduction zone. A subduction zone is an area where two of the Earth’s tectonic plates converge, one sliding beneath the other, generating the largest earthquakes on Earth, many with destructive tsunamis.

Findings of a study on sediment samples found far below the seabed are now detailed in a new paper authored by Dr. Andre Hüpers of the MARUM-Center for Marine Environmental Sciences at University of Bremen and published in the journal Science. Colorado School of Mines Associate Professor of Geophysics Brandon Dugan was one of the study’s coauthors and coleader of Expedition 362.

“It raised a lot of questions, because that wasn't a place in the world where we thought a magnitude 9 earthquake would occur,” said Dugan.

Expedition coleader Professor Lisa McNeill of the University of Southampton said “the 2004 Indian Ocean tsunami was triggered by an unusually strong earthquake with an extensive rupture area.” By unearthing the cause of such a large earthquake and tsunami, the scientists hope to be able to assess potential hazards in other regions with similar geological properties.

The scientists concentrated their research on a process of dehydration of sedimentary minerals deep below the ground, which usually occurs within the subduction zone. It is believed this dehydration process, which is influenced by the temperature and composition of the sediments, normally controls the location and extent of slip between the plates, and therefore the severity of an earthquake.


Expedition leaders from left: Lisa McNeill, Brandon Dugan, Katerina Petronotis.
Expedition leaders from left: Lisa McNeill, Brandon Dugan, Katerina Petronotis. (Photo credit: Tim Fulton, IODP JRSO.)

The Sumatra research team used the latest advances in ocean drilling to extract samples from 1.5 km below the seabed, taking measurements of sediment composition including chemical, thermal and physical properties.

At a certain depth, the researchers identified a layer where the water had lower salinity than the overlying and underlying sediment. This evidence of freshwater suggests that the water must have been released from within minerals in the sediment, as ocean water would have been high in salinity.

The researchers found that the sediments on the ocean floor, eroded from the Himalayan mountain range and Tibetan Plateau and transported thousands of kilometers by rivers on land and in the ocean, were subjected to geologic processes over millions of years. These sediments formed a sort of thick shell over minerals far below the seabed, causing chemical transformations within the subsurface.

 A 'free-fall funnel', part of the drilling process.(Photo Credit: Tim Fulton, IODP JRSO)

 A 'free-fall funnel', part of the drilling process.
(Photo 
Credit:Tim Fulton, IODP JRSO.)

These transformations caused the mineral bed to heat, pushing freshwater out of the mineral crystals up through the sediment layers.

At first, this water would have softened the sediment, actually decreasing the risk of a big earthquake by allowing it to absorb more force, Dugan explained. However, as the sediment moved closer to the fault over millions of years, the water flowed away, leaving the sediment dehydrated and brittle—the perfect setup for a megaquake.

The scientists ran simulations to calculate how the Sumatra sediments (currently not yet to the fault) would behave once they had traveled 250 km to the east toward the subduction zone and been buried significantly deeper. The simulations showed the sediment reaching higher temperatures, thus supporting their findings.

Hüpers said that the findings suggest that other subduction zones with thick and hotter sediment and rock could also experience this phenomenon.

“The 2004 Sumatra and 2011 Tohoku earthquakes made us reexamine our understanding of large earthquakes,” said Dugan. “This new analysis extends our knowledge of the conditions that can contribute to large earthquakes that generate tsunamis. We now can assess the potential for megaquakes in subduction margins with limited or no historical earthquake record.”

Subduction zone earthquakes typically have a return time of a few hundred to a thousand years, so applying this research to similar geological regions will allow scientists to better predict these hazards.

Similar subduction zones exist in the Caribbean (Lesser Antilles), off Iran and Pakistan (Makran), and off the western United States and Canada (Cascadia). The team will continue research on the samples and data obtained from the Sumatra drilling expedition over the next few years, including laboratory experiments and further numerical simulations, and will use their results to assess the potential future hazards both in Sumatra and at these comparable subduction zones.
 

 
 
Contact:
Agata Bogucka, Communications Manager, College of Earth Resource Sciences & Engineering | 303-384-2657 | abogucka@mines.edu
Mark Ramirez, Managing Editor, Communications and Marketing | 303-273-3088 | ramirez@mines.edu
 

 

Researchers at Colorado School of Mines, in partnership with the Department of Energy’s National Renewable Energy Laboratory and the University of Chicago, have developed new designer quantum dot systems with greater control over beneficial properties for photoelectrochemical and photovoltaic applications. Their research has been published in the May 16, 2017, edition of Nature Communications.

The paper, “Tuning Colloidal Quantum Dot Band Edge Positions through Solution-Phase Surface Chemistry Modification” focuses on chemical modifications the scientists were able to achieve to lead sulfide quantum dot (QD) surfaces so that their ionization energy—the amount of energy needed to remove a single electron from the solid—could be systematically tuned over an unprecedented range. Mines Chemistry Professor Alan Sellinger and graduate student Brett McNichols are coauthors on the paper.


Mines Chemistry Professor Alan Sellinger and graduate student Brett McNichols

“This interdisciplinary research is a true team effort of computational chemistry (University of Chicago), synthetic chemistry (Colorado School of Mines) and materials chemistry/characterization (NREL),” says Sellinger

Quantum dots are considered to be pseudo-atoms that have highly tunable opto-electronic properties. Researchers are studying films of QDs as functional solids in a variety of applications, including displays, lighting, solar cells and solar photoelectrochemical cells. In a typical solid, the ionization energy is determined from the constituent atoms and in general cannot be modified. In QD solids, however, the ionization energy as well as other beneficial opto-electronic properties can be modified in controlled and rational ways.

The research also established the fundamental principles that govern the relationship between a QD and ligand, which are organic molecules chemically attached to the QD surfaces. Prior studies have shown that modifying the surface of the QDs can change the overall ionization energy, but a clear and quantitative relationship hasn’t been reported until now.

Authors from NREL includes Matthew Beard, Daniel Kroupa, Elisa Miller, Jing Gu and Arthur Nozik, and they were also joined by University of Chicago researchers Marton Voros, Nicholas Brawand and Giulia Galli.

Contact:
Megan Hanson, Communications Manager, College of Applied Science and Engineering | 303-384-2358 | mhanson@mines.edu
Mark Ramirez, Managing Editor, Communications and Marketing | 303-273-3088 | ramirez@mines.edu

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