Permanent URI for this collection
Browse
Recent Submissions
Publication Facile method for making monodispersed colloidal plantinum nanocrystals, A(Colorado School of Mines. Arthur Lakes Library) Snow, Kyle; McCann, Kevin; Yang, YonganPlatinum nanoparticles are extremely small clusters of Pt atoms, usually 1-50 nanometers (nm) in width, homogeneously dispersed in a colloidal solution. Pt nanoparticles have excellent catalytic strength, even more so than bulk platinum. This is due to nanoparticles' high surface area to volume ratio. Shape also plays a large role in particle functionality. Pt nanoparticles by themselves have a high tendency to agglomerate, which hinders their effectiveness. For this reason, molecules called ligands are used to bind to the surface of the particles, stabilizing them and preventing agglomeration. Despite platinum's high cost, it is still by far the best catalyst for these fuel cell reactions. Therefore, it is important to develop methods of Pt nanoparticle synthesis in a way that is simple and more cost-effective than the methods currently in use. The objectives of this research are to develop optimal parameters for our AVINS method of nanoparticle synthesis, to control the particle size between 1-15 nm, and to be successful in ligand exchange by transferring the particles from their original aqueous solution into a nonpolar solvent such as toluene or hexane.Publication Horizontal deposition of polystyrene colloids for enhanced light trapping in solar cells(Colorado School of Mines. Arthur Lakes Library) Omkamoto, Kento; Wu, Ning; Ma, FuduoMotivations: A majority of solar cells base their materials off of silicon wafers about 180-300 microns in thickness due to it being very cost efficient in the market. However, when the thickness of silicon wafers are reduced, they are only able to create energy on the visible light spectrum for solar rays. Because light on the infrared spectrum is not effectively absorbed when making thinner silicon wafers, a proposal to implement metal particles into the wafer to scatter light has been suggested. Light enters the solar cell but is scattered because of metal particles uniformly placed on top of the wafers. Light is then trapped between the semiconductor due to high angles the light is scattered at. This results in a more effective absorption of solar energy. The goal of this work is to fabricate polystyrene particles on a substrate with a uniform monolayer. And then find an effective chemical to mix with the particles to evenly separate the particles so they are not touching each other.Publication Performance analysis and introduction to optimization of ParFlow(Colorado School of Mines. Arthur Lakes Library) Sanders, Kevin; Kaiser, TimothyParFlow is an open-source, object-oriented, parallel watershed flow model. It includes fully-integrated overland flow, the ability to simulate complex topography, geology and heterogeneity and coupled land-surface processes including the land-energy budget, biogeochemistry and snow (via CLM). It is multi-platform and runs with a common I/O structure from laptop to supercomputer. ParFlow is the result of a long, multi-institutional development history and is now a collaborative effort between CSM, LLNL, UniBonn and UCB. This work aims to: get ParFlow to build and compile with instrumentation in order to collect data about the runtime and event timeline of the program; use the collected data to analyze scalability, computation vs. communication and the overall efficiency of the program; and, using this information, pinpoint possible weak points in the code that can be improved and make the necessary changes in an attempt to make the program run faster.Publication Renewable energy applications for oil shale drilling(Colorado School of Mines. Arthur Lakes Library) Salomon, ViolaineExtracting oil shale requires a large amount of energy for heating and pyrolyzing the rock. Using renewable energy sources is a good opportunity to reduce the overall carbon footprint. This poster details thermal solar as an energetic solution and compares different renewable energy sources, as well as their consumption water, greenhouse gas emissions and embodied energies. All the calculations are based on energy calculations to extract 100,000 barrels of oil shale per day of rich (30 gal/ton) and medium (20 gal/ton) oil shale provided by Alan Burnham of American Shale Oil (AMSO).Publication Raman spectroscopy of silicon quantum dots(Colorado School of Mines. Arthur Lakes Library) Kurchin, Rachel; Kendrick, Chito; Collins, Reuben T.; Furtak, Thomas E.Silicon quantum dots are synthesized and studied extensively by REMRSEC, but they have not thus far had a fast and reliable way to characterize them. In this work, Raman spectroscopy is employed to study dots in varying types of samples, with special attention paid to the effects excessive laser power density can have on amorphous silicon.Publication Micro-scale mechanical properties of NMC lithium ion battery cathodes(Colorado School of Mines. Arthur Lakes Library) Musselman, Matt; Wilkinson, Taylor; Smith, Kandler; Packard, Corinne E.This work aims to update current lithium ion battery lifetime models in order to provides more accurate predictions on batteries for use in electric/hybrid cars. This requires new physics-based models and an understanding of mechanical degradation factors of NMC particles and the properties of each component over the life span. Thus, this work will measure the mechanical properties of individual particles using nanoindentation to develop a better understanding of the fundamental material physics behind battery degradation and to standardizes material preparation techniques and testing procedures.Publication Centrifugal sieving for the size separation of lunar regolith in microgravity(Colorado School of Mines. Arthur Lakes Library) Martinez, Myles; Fruit, John; Dreyer, Christopher B.; Walton, Otis; Riedel, NedFor any microgravity environment traditional sieving methods used on earth can fail or be less effective for smaller size particles. Previously a device was designed and built that uses centrifugal force created by a spinning screen to push material through and a spinning helical auger to create shear flow to sieve independent of gravity. Power consumption of the motors was monitored via two ammeters and blinding of the screen was monitored regularly with a camera that can take pictures of the screen in between tests. By determining the operating conditions that sieve most effectively and consume the least amount of power more effective optimization the centrifugal sieve can be achieved.Publication Gas hydrate adhesion to mineral surfaces(Colorado School of Mines. Arthur Lakes Library) Leith, William J.; Aman, Zachary M.; Sum, Amadeu K.; Koh, Carolyn A.Hydrates are crystalline inclusion compounds, where water forms cages that encage 'guest molecules' (typically hydrocarbons). The amount of energy stored in gas hydrates is estimated to be twice that of traditional fossil fuels. These deposits are found below the permafrost and under the ocean floor in contact with sediments. Therefore, this work aims to characterize adhesion force between gas hydrate quartz and calcite surfaces and relate adhesion force to chemical and physical properties of minerals.Publication Using AFM to find evidence of conformal monolayers(Colorado School of Mines. Arthur Lakes Library) Meinig, Erich; Brenner, Thomas; Chen, Gang; Collins, Reuben T.; Furtak, Thomas E.Atomic force microscopy (AFM) is one of the tools used to infer whether a conformal monolayer of the surface treatment exists. AFM roughness measurements can be used to detect changes in height before and after surface treatment. This work aimed to measure the existence of such layers.Publication Novel bimetallic catalysts for use in anion exchange membrane fuel cells(Colorado School of Mines. Arthur Lakes Library) Sather, Nicholas A.; Ham, James M.; Herring, Andrew M.; Greenlee, Lauren F.Widespread implementation of current fuel cell technology is inhibited by the scarcity and price of the catalysts on both the anode and cathode. However, recent research suggests that Alkaline Anion Exchange Membrane Fuel Cells (AAEMFC) can operate with earth abundant materials as catalysts due to the rapid reaction kinetics in alkaline environments. This research investigates the electrocatalytic properties of a novel bimetallic catalyst in the oxidation of methanol, ethanol and methane fuels for use in AEM fuel cells.Publication Renewable energy and climate change education(Colorado School of Mines. Arthur Lakes Library) Kawaguchi, Kelsey; Howell, Cynthia; Munakata Marr, Junko; Mitcham, CarlTo identify barriers to incorporating climate change (CC) education into high school and community college courses, 24 national educators were interviewed. During each 30-minute recording, instructors described experiences with: (1) what courses are taught, (2) the depth of CC coverage, (3) what was the motivation to include CC, (4) opportunities for CC education in the future, (5) ultimate barriers to incorporating CC, (6) how CC is discussed and/or considered, (7) how CC can be a dimension in design of engineered systems and/or solar, wind, and buildings technician training. The participants were experts in energy/renewable energy, preparing the energy workforce, teaching/directing programs, technician training of students seeking 2 and 4-year degrees and managing energy companies.Publication Spatial frequency modulation for imaging (SPIFI) in optical and mid-IR wavelength systems(Colorado School of Mines. Arthur Lakes Library) Johnson, Nicole; Corchado, Jaime; Squier, Jeff A.; Toberer, EricThis work aims to use a single element detector for 2D imaging. The work uses frequency encoding to eliminate the need to scan in the direction of line focus and it uses a Fourier transform detector signal to recover frequency space representation of the object.Publication Deformation of indium oxide nanostructures, The(Colorado School of Mines. Arthur Lakes Library) Gomez, Stephanie; Kumar, Mukesh; Packard, Corrine E.The development of nanowire technology is important for the application of small and compact devices to replace bulk material and has been a subject of great interest due to their potential in advancing field effect transistors. Nanowires are better for transistor devices because they are a single crystal grown from the bottom-up approach and thus allowing for a controlled gate length. Understanding the mechanical properties will determine the reliability of the nanowire devices.Publication Centrifugal sieve segregation in micro gravity(Colorado School of Mines. Arthur Lakes Library) Fruit, John Terrell; Martinez, Myles Kristian Alexander; Dreyer, Christopher B.; Walton, OtisSieving in space could be crucial to applications such as yielding smaller material for construction and extraction. Thus, improvements were implemented to a centrifugal sieve which included: Labview operating VI for motor control; power measurement via current; screen replacement and maintenance; Shaker subVI ('Jolt command'). In addition, the lunar simulant JSC-1a was tested through the system to analyze the sieve's efficiency with 100 micron screen. This can also play a role in eliminating foul material that could otherwise clog systems. The following data proves that sieving at lower speeds may prove more efficient based on the yields obtained from experimentation and the current data.Publication Benzoic acid surface functionalization of conduction band engineered Zn1-xMgxO layers for enhanced organic/inorganic photovoltaics(Colorado School of Mines. Arthur Lakes Library) Flores, Thomas; Brenner, Thomas; Chen, Gang; Furtak, Thomas E.; Collins, Reuben T.Increasing the efficiency of organic/inorganic photovoltaics will open the door to a cheap, easy, and safe means to bring solar energy to the masses. A key role in raising this efficiency is by maximizing the band gap offset between donor HOMO and acceptor conduction band. Organic/inorganic photovoltaics are excitonic devices; they create an electric current by splitting an exciton produced in a donor layer whose electron is transferred from the donor to an acceptor, which then pushes the electron through to a conducting surface, producing a current. The efficiencies of these cells are extremely dependent upon the energy offset between the donor HOMO and acceptor conduction band - a larger offset ensures a higher VOC, which leads to higher efficiencies. One can perform conduction band tuning by alloying or introducing molecular dipoles to the surface. However, adsorbing these molecules to the surface often has negative effects, such as strong etching of the acceptor layer, ultimately rendering the device less effective. Therefore, this work alloys ZnO with Mg to stifle the negative etching effects of acid adsorption, thereby retaining all the necessary absorption properties for electrical photoconversion. And it will study the bonding nature of carboxylic groups to the alloyed ZnO layer for refined preparative measures to produce the highest quality layers at the lowest cost.Publication Catalyst-free 'click chemistry' of zinc oxide surfaces(Colorado School of Mines. Arthur Lakes Library) Evans, Charlotte; Brenner, Thomas; Chen, Gang; Collins, Reuben T.; Furtak, Thomas E.Click chemistry' describes reactions that can modify the surface functionality of a material simply and quickly by joining small molecules together. In this research, a five step process was developed involving the surface modification of zinc oxide surfaces with propiolic acid and 'clicking' with azidobenzene or 1-azido-4-fluorobenzene without the use of a catalyst. This process successfully modified the surface as determined by water contact angle, AFM imaging, absorption spectra, and PM IRRAS measurements.Publication Optical spectroscopy of hybrid organic/inorganic solar cell materials(Colorado School of Mines. Arthur Lakes Library) Cruz, Jose; Chen, Gang; Otnes, Gaute; Kendrick, Chito; Furtak, Thomas E.; Collins, Reuben T.Although global energy demands are satisfied by fossil fuels, environmental sustainability is not possible. Due to a need for clean, renewable energy resources, we explored using inorganic photovoltaics as a primary resources for harvesting solar energy. The research found that Si-QD loading to solar cell materials increased the amount of light absorbed. The research also tested a P3HT solution with Si-QD suspension and found that the addition of Si-QD has practically no effect on the shape of P3HT. It also found that the intensity decreased proportionally with the addition of Si-QDs in DCB.Publication Synthesis of earth-abundant and nontoxic nanomaterials for sustainable energy: colloidal 3C-SiC quantum dots through a room temperature bottom-up method(Colorado School of Mines. Arthur Lakes Library) Davidson, Malcolm; Cloud, Jaqueline E.; Yang, YonganMotives for Silicon Carbide Quantum Dots: Enhanced intensity and chromatic quality as LED's; High intensity emission and low toxicity as biomarker candidates; Size dependent band gap; Applications in photo-electrolysis of water, reduction of organics for self cleaning surfaces, light harvesting components for hybrid and classic solar cells.Publication Synthesis of phase pure tungsten carbide for high temperature H2 membranes(Colorado School of Mines. Arthur Lakes Library) Brennan, Karl; Parks, Sterling; Ostwal, Mayur; Way, J. Douglas; Wolden, Colin AndrewThe Pt.-like catalytic behavior of transition metal carbides has been recognized for several decades. However, their potential as robust, highly selective membranes for the steam reforming of methane is only now being realized. The synthesis and properties of molybdenum carbide are well understood and have been previously studied by this research group. This study aims to apply the body of knowledge gained through previous work with Mo2C to investigate a new material: tungsten carbide. This paper aims to develop a robust, reproducible procedure for synthesis of phase-pure tungsten carbides. Greater than 95% of the 50 million tons of H2 produced annually is derived through steam reforming of fossil fuels, which requires energy-intensive separation processes. Membranes offer the potential of significant process simplification and energy reduction, particularly when reforming is combined with the water gas shift reaction and CO2 capture. Carbide composite membranes offer earth abundant alternatives to Pd.Publication Atomic-scale characterization of CdTe PV through atom probe tomography(Colorado School of Mines. Arthur Lakes Library) Boxer, Kevin S.; Gorman, Brian P.; Barnes, Teresa M.CdTe solar cell technology uses a thin film photovoltaic device, which has become increasingly cost competitive, with the potential to reduce the use of fossil fuels with a favorable balance of cost and efficiency. Atom probe tomography lets us use a local electrode atom probe and laser-induced field evaporation to discover the chemical composition measurements at the atomic scale and with 3D imaging and analysis. Future work could entail performing additional APT trials with variations in composition to determine effect on properties and increase energy conversion.