Sheryl H. Ehrman - US grants

CTS-9973845
Sheryl Ehrman
University of Maryland, College Park


Discrete quantities of materials (nanoclusters), whether separated by grain boundaries, or by gas or liquid molecules have very interesting and potentially very useful material properties which may differ significantly from those of their bulk counterparts. In this project, the growth of compound semiconductor nanoparticles from the gas-phase will be simulated assuming a collision/sintering mechanisms of particle growth. Results from this work will be important for the design of larger scale processes for nanoparticle synthesis, and, more fundamentally, for increasing our understanding of phenomena occurring during particle formation.

This award is made in response to the POWRE solicitation.

0093649
Ehrman

Much recent progress has been made towards the development of techniques for the controlled synthesis of nanoparticles. A need now exists for methods of creating functional materials from nanoparticles while preserving their small grain size. In this project, a hybrid high temperature particle synthesis/low temperature interconnection process will be developed for production of mechanically strong porous films. With this process, porous films will be produced with no grain growth, thus preserving properties associated with nanoparticle size. The initial focus will be on porous films of titania, with applications to photovoltaic materials and chemical sensors. This general technique may also be applicable to the production of porous films of many other materials such as silica or tin oxide.
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The research component will lead to an improved understanding of the mechanisms of particle transport and processing/structure/property relationships for nanoparticle-based materials. This will be integrated with the educational component through the development of an undergraduate elective in the area of particle science and technology, and by incorporating numerical methods used for this research into the required graduate level transport phenomena course, in the form of project-based team activities. Outreach activities will consist of visits to high schools and junior high schools in Washington, D.C., as these students are now able to attend the University of Maryland as 'in state' students. These visits are directed towards increasing the number and diversity of qualified applicants to the College of Engineering, and towards increasing the awareness of chemical engineering as a career option.

This award provides funding for a 3 year continuing award to support a Research Experiences for Teachers (RET) in Engineering Site program at the University of Maryland (UMD)College Park in partnership with the University of Virginia (UVA) entitled, "Research involving Design, Innovation and Invention Experiences for Teachers (Research DIIET)," under the direction of Dr. Leigh Abts.

This Research Experiences for Teachers (RET) in Engineering Site involves a rigorous six-week summer research schedule of active learning activities for a total of 39 middle and high school science teachers,13 each year for three years at both the UMD and the UVA campuses. The program also includes an academic year action research project. The teachers will be recruited from the Montgomery County, Maryland Public School System, the Danville and Pittsylvania Public Schools in Virginia and the Washington D.C. Friendship Public Charter School. The teachers will explore the 'abstract notion of innovation'-from basic scientific discovery to applied product development and will create classroom modules.

CBET-0755703, Ehrman

Project Summary: The objective of this project is to develop a spray pyrolysis process for the production of metal alloy microparticles from inexpensive metal salt precursors.
A team consisting of student, faculty and industrial researchers from DuPont and the
University of Maryland will conduct experimental and simulation based studies in order to develop a comprehensive understanding of relationship between process conditions and product characteristics.

Intellectual Merit: Spray pyrolysis processes offer many advantages over solution phase routes for powder production, but extension to metals on an industrial scale has been restricted to only a few oxidation resistant systems such as silver and palladium. The requirement of addition of high concentrations of reducing gas to produce metallic particles has limited extension to base metal production. In our approach, the cosolvent decomposes in the reactor to produce small amounts of hydrogen, less than the flammability limit in air, reducing metal salt crystals to metallic powders. The process is governed by both kinetic and thermodynamic constraints. Chemical kinetic modeling of the decomposition process will be used to predict hydrogen evolution while thermochemical modeling to determine equilibrium phase relationships as a function of oxygen concentration and temperature will be used, together with a mass and energy balance based process model, and statistical based quality control concepts to guide process design. With this project, the team will take the process from bench scale single component proof of concept stage to multicomponent alloy powder formation, including process scale up and applications testing.

Broader Impact: The target application is thick film conductive pastes used in the production of microcircuit materials, for example in hybrid integrated circuitry, embedded passives to enable shrinkage of components and metallization of multilayer ceramic capacitors. End products containing microcircuit materials are ubiquitous, ranging from cell phones to solar cells to automobiles. Better quality materials will lead to improved communications and safety, greater energy efficiency, and other improvements affecting quality of life. Aerosol-based production routes, which are rapid and often single step, and which produce solvent and ligand free product powders, also present a general opportunity for promotion of sustainability in manufacturing. Beyond electronic materials, metal powders are of interest for dental and medical implant applications as well as medical devices such as in glucose monitors for diabetics, and thus results from this research may impact these industries as well. Elements of the value added by the proposed industry-university collaboration include: (1) fusion of fundamental principles of reaction engineering, aerosol technology and materials science with industrial process development and scale up activities, and (2) interactions between industry and university researchers and students that will allow participation at all stages from laboratory innovation to applications testing and extension of the research to inform teaching and outreach activities with a real world perspective.

The conversion of solar energy into solar fuels provides long-term storage and transport of the world?s most abundant but intermittent source of energy. In the transition from fossil fuels to hydrogen as an energy carrier, materials science will play an unprecedented role. Significant materials challenges exist in the production and storage of hydrogen related to development of renewable hydrogen energy based technologies. This joint effort between the University of Maryland and the Dayalbagh Educational Institute in Agra, India, implements a systematic study focusing on design, synthesis and evaluation of inexpensive, abundant and stable transition metal oxide semiconductor materials, hematite, titania and copper oxide, with end applications in photoelectrochemical production of hydrogen. The team brings together expertise in nanomaterials synthesis and characterization (US/India), and photoelectrochemistry (India). The objective is to improve the state-of-the-art for this class of photoactive materials through careful integration of synthesis, characterization, and simulation, and to use this basis for substantial fundamental advances in materials design.

Through scientific exchange, as well as exchanges of personnel, the team develops significant intellectual infrastructure for materials research, as well as optimizes use of instruments and facilities at each of the partner institutions in this international collaboration. Beyond the laboratory, recognizing that advances in materials science will not be translated into improved quality of life without a well-trained scientific and engineering workforce, the multidisciplinary and multinational team and the timely topic of materials for hydrogen generation will attract and retain more students in the science, technology, engineering and mathematics (STEM) pipeline.

This award is co-funded by the NSF Office of International Science and Engineering.

CBET-0828410
Adomaitis

Since the original demonstration of photo-assisted water electrolysis by Fujishima and Honda in 1972, tremendous effort has gone into developing photoelectrochemical (PEC) materials and systems. Numerous research programs have focused on improving the efficiency of these devices, and of those that have been successful, few have addressed the issue of whether such devices would be practical or environmentally desirable to manufacture on the scale necessary to impact the US's energy requirements.

The PIs plan to develop new semiconductor materials and solar cell devices for the production of hydrogen by the PEC decomposition of water with a manufacturing and product lifecycle perspective. The PEC materials development program builds directly on the complementary skills of the project PIs: the Adomaitis group's combinatorial chemical vapor deposition (CVD) reactor designs for material property and manufacturability optimization, and the Ehrman group's expertise in developing nanostructured films of doped copper oxide for PEC applications by flame synthesis and other manufacturing techniques.

Intellectual Merit:

The intellectual merit is defined in terms of three specific technological challenges to be addressed. The first consists of an approach to semiconductor thin-film processing: the PIs plan to demonstrate model-based combinatorial CVD for rapid development of semiconductor materials of optimal efficiency for PEC applications. The second goal is to efficiently investigate, by single-substrate design-of-experiment procedures, the complete range of nanostructured CuO1 film performance, particularly as a function of film morphology. Finally, they will apply the validated process simulators developed in this experimental/computational proposal to investigate the feasibility of using current commercial CVD reactor systems as a means of shortening the path to commercialization of our PEC devices.

Broader Impact:

The outcomes of this research program have the potential to broadly impact green manufacturing and energy production technologies. The production of H2 from the solar-powered splitting of water constitutes a sustainable energy supply in that the solar devices are to be manufactured from abundant and benign precursors with virtually no manufacturing waste products. This solar hydrogen production approach will integrate naturally into solar energy systems that enable more efficient use of the full solar spectrum.

The three educational initiatives will bring new technological and economic aspects of solar energy production into the classroom. A major capstone design project is planned where senior chemical engineering students will evaluate the economic potential of large-scale H2 production based on the semiconductor materials developed in the research.

Sprays are used in a variety of technology intensive industries from microelectronic manufacturing to fire-protection applications. Because of the complexity of the physical processes associated with atomizing a continuous stream of fluid into a spray and the difficulty associated with characterizing atomization details, spray formation and its relationship to injection conditions is poorly understood. As a result, spray related development is inhibited by analytical concessions, which rely primarily on "cut and try" and empirical approaches. However, as computer based design tools become increasingly popular, detailed atomization models will be needed for computer-aided development, analysis, and evaluation of spray devices and systems. It is essential to precisely characterize engineered sprays in order to develop models to describe their behavior and to leverage this understanding for advancements in spray technology. Building on existing instrumentation and laboratory infrastructure, this team seeks to develop a major instrument capable of characterizing large-scale sprays (e.g. sprays used in fire suppression applications) while also providing the capability to interrogate small-scale sprays (e.g. sprays used in microelectronic applications). The Spatially-resolved Spray Scanning System (SSSS) expands on ideas from the PI's NSF PECASE research and a recent UM invention (PP: 61/548530) that allows for scanning the near-field of large-scale fire suppression sprays.

1336581
PI: Ehrman

Spray pyrolysis processes can be used to make unique materials not accessible via traditional precipitation or vapor deposition processes. Additional advantages include scalability and solvent free final product powders. Aerosol production of oxidation resistant materials such as silver and palladium has been demonstrated, but extension to lower cost base metals on an industrial scale has been challenging. The objective of this project is to develop a mixed-phase spray pyrolysis route for producing multicomponent base metal powders with increased protection against oxidation, for printable electronics applications including hybrid integrated circuitry and metallization of solar cells. Spray pyrolysis will be used to achieve kinetic control of microstructure, enabling formation of particles that cannot be made by other means. The test bed will be particles that contain both copper and copper/tin alloy, but the processing approach will be broadly applicable to other material systems. A team consisting of student, faculty and industrial researchers from DuPont and the University of Maryland will conduct experimental and simulation based studies to overcome technical hurdles associated with mixed phase powder processing. This team draws upon University of Maryland expertise in chemical engineering, materials characterization and aerosol technology and DuPont expertise in materials chemistry, powder processing, and statistical design of experiments.

Results of this work will enable incorporation of low cost base metals into conductive pastes, leading to overall reductions in cost for solar cells, electronics and medical devices. Use of aerosol based production routes for metal powders will realize additional environmental and cost benefits over conventional precipitation-based processes. Elements of the value added by this project include: (1) fusion of industrial and academic perspectives (2) interactions between industry and university researchers and students that will allow participation at all stages from laboratory innovation to applications testing and (3) interjection of real world elements into activities and research experiences for pre-college and undergraduate students.

1438400
Ehrman

Regional Air Quality Impact of Natural Gas Production Operations

Rapid expansion of natural gas (NG) production operations in the United States has irreversibly altered the energy landscape. Upsides include low cost fuel and chemical industry feedstocks, resulting in a boost to the economy and in new and expanded plant capacity. Downsides include concern about environmental degradation of groundwater, and about the impact of air emissions of air toxics and ozone forming precursors such as nitrogen oxides and reactive volatile organic compounds (VOCs), and the resulting immediate impact on public health, as well as air emissions of methane, a potent greenhouse gas. This project will lead to toolsets that can be used by a variety of constituents to improve predictions of fate and transport of air pollutants, and to identify effective regulatory policy measures to reduce impact of NG operations. Products of this research will include improved understanding of vertical mixing parameterization for improved accuracy in predicting regional scale transport of area source emissions, model-ready updated emissions estimates, and well documented scenarios available for evaluating impacts of policy changes. Concerns regarding transport of area source emissions extend beyond NG operations to emissions from non-electricity generating NOx sources and vehicle emissions as well as biogenic emissions. Model-ready emissions estimates can be used by a variety of constituents including regulatory and community organizations and the oil and natural gas industry. Hands on research activities for high school and undergraduate students will support personnel development. The emphasis of this work is the Marcellus shale play but approaches and products developed will be useful for other regions of the US and world.

This proposal will investigate the regional nature of emissions from NG production operations including modern horizontal drilling and hydraulic fracturing. The primary testable hypothesis is that ground level air emissions of even short-lived species can be significant regional sources of pollution through vertical transport and advection. Rigorous analysis of ground level and aloft aircraft measurements of methane, VOCs, NOx, and PM2.5, including those made during the NASA DISCOVER-AQ campaign will be performed. Receptor based source apportionment will be conducted for multiple sites in the mid-Atlantic region. To improve our ability to simulate regional transport, existing vertical transport parameterization schemes available within the Community-scale Modeling and Air Quality (CMAQ) platform will be evaluated for several episodes in the mid-Atlantic region of the US for 2007 and 2011. Regional ground level monitoring data will be aggregated from several states and combined with a short aircraft field campaign, using upwind and downwind spirals and plume transects to evaluate degree of agreement between our model predictions of vertical transport and downwind dispersion and measurements. Building on a long-standing cooperation with State (MD, CT, DE, NH) and regional (OTC/MANE-VU) Air Quality managers the PIs will partner to develop and evaluate possible future case scenarios.