Engineering Commons^™

The Development Of 6.7% Efficient Copper Zinc Indium Selenide Devices From Copper Zinc Indium Sulfide Nanocrystal Inks, Brian Kemp Graeser

Open Access Theses

As solar cell absorber materials, alloys of CuIn(S,Se)2 and Zn(S,Se) provide an opportunity to reduce the usage of indium along with the ability to tune the band gap. Here we report successful synthesis of alloyed (CuInS2 )0.5(ZnS)0.5 nanocrystals by a method that solely uses oleylamine as the liquid medium for synthesis. The reactive sintering of a thin film of these nanocrystals via selenization at 500 °C results in a uniform composition alloy (CuIn(S,Se)2 )0.5 (Zn(S,Se)) 0.5 layer with micron size grains. Due to the large amount of zinc in the film, the sintered grains exhibit the zinc blende structure instead …

Spectroscopic And Kinetic Study Of Copper-Exchanged Zeolites For The Selective Catalytic Reduction Of Nox With Ammonia, Shane Adam Bates

Open Access Dissertations

The recent application of metal-exchanged, small-pore zeolites for use in the selective catalytic reduction (SCR) of NO_x with ammonia NH₃ for automotive deNO_x applications has been a great stride in achieving emission standard goals. Copper-exchanged SSZ-13 (Cu-SSZ-13), the small-pore zeolite in this study, has been shown to be very hydrothermally stable and active under conditions presented in the exhaust of the lean-burn diesel engine. In this work, detailed studies were performed to identify many aspects of the active site(s) in Cu-SSZ-13 in order to learn about the standard SCR mechanism.

A series of seven Cu-SSZ-13 samples were …

New Effects Of Aging And Lattice Intercalation On Surface Properties Of Titanate Nanobelts, Roger Williams

Graduate Theses and Dissertations

Titanate nanobelts (NBs) have structural characteristics beyond that of clays. Due to a negatively charged lattice matrix of edge-shared TiO6-octahedra, the location of intercalated cations within the interlayer space may dictate the charge-conductions. This environment may in turn govern the lattice-framework's stability and surface properties, based upon our preliminary

data.

On that basis, these nanomaterials have been found in our lab to possess superb biological compatibility that is closely related to the types of the intercalated cations. In addition, a prolonged agitation was proven to enable us to manipulate the titanate NBs' length. In a parallel study, a ripening was …

Refractive Index Chemical Sensing With Noble Metal Nanoparticles, Phillip Blake

Graduate Theses and Dissertations

Chemical sensing is a key component in modern society, especially in engineering applications. Because of their widespread impact, improvements to chemical sensors are a significant area of research. One class of sensors, plasmonic sensors, is being heavily researched because of their ability to detect low levels of analyte in near real time without destroying the analyte. This work studies a new class of plasmonic sensor that utilizes diffractive coupling to improve sensor performance. Specifically, this work outlines the first study of diffractive coupling sensors with typical nanoparticle shapes. Sensitivity of this new class of sensor is directly compared to typical …

Computational Studies Of Ion Transport In Polymer Electrolytes, Hui Wu

Doctoral Dissertations

Improving ionic conductivity and lithium mobility in polymer electrolytes is important for their practical use for battery electrolytes. In this study, a combination of molecular dynamics and Monte Carlo simulations was used to bring insight into lithium ion transport in poly(ethylene oxide) (PEO) with plasticizers and also next to alumina solid surface doped with lithium salt. The simulations were performed using a moderately high molecular weight polymer (Mn = 10,000 g/mol) at an EO:Li ratio of 15. For the plasticized system, the PEO with LiN(CF3SO 2)2 (LiTFSI) was mixed with 10 wt% plasticizers that included either cyclic ethylene carbonate …