Browsing by Author "Hammond, Nikki"
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Item Computationally modeling the effectiveness of Pd/Cu as a diesel oxidation catalyst(2023-04-13) Hammond, Nikki; Hoang, NhiDiesel engine emissions are a major cause of air pollution producing carbon monoxide (CO), hydrocarbons, nitrogen oxide molecules (NOx), and particulate matter (PM). Low temperature combustion engines offer a promising solution for reducing NOx and PM emissions, but in turn, the lower temperature interferes with the diesel oxidation catalyst (DOC) causing an increase in CO and hydrocarbon emissions. To combat this, the development of new catalysts is critical. Recent studies show that a Pd/Cu alloy could lead to inhibition-free low temperature oxidation reactions, but the mechanistic origin of the improvement over Pd/Pt alloys remains unknown. To elucidate the mechanism, we first used SurfaceEP, a machine-learning package to rapidly estimate binding energies and identified certain ensembles with promising oxygen binding properties. For isolated Pd atoms in the surface of Cu, we obtained density functional theory (DFT) data for all CO oxidation steps. We are currently incorporating this information into a kinetic Monte Carlo (kMC) model, which will allow us to study the mechanism and activity of well-defined site ensembles. This will provide the necessary fundamental insight that is required to further improve the composition and surface architecture of Pd/Cu diesel oxidation catalyst.Item How Childcare Can Bridge the Gender Gap In STEM(2021-04-01) Hammond, Nikki; Isik, Baycha; Khan, KiranParenthood concerns have disproportionately affected female retention in STEM careers due to gender stereotypes. Compared to their male counterparts, counterparts, women were 20% more likely to leave a full time STEM career after the birth or adoption of a child with a total of 43% of women doing so. This inequality needs to be addressed to alleviate growing issues in research including a male bias. Our proposed solution is to encourage more tech companies to invest in on site daycare facilities. The institutions with better childcare facilities have twice the number of female faculty in STEM. This offers a number of benefits for the economic productivity of the company, development of children, and representation of women in the field.Item Using predictive modeling to improve catalyst performance in low temperature diesel combustion(2022-04-14) Hammond, NikkiDiesel engine emissions are a major cause of air pollution producing carbon monoxide (CO), hydrocarbons, nitrogen oxide molecules (NOx), and particulate matter (PM). Low temperature combustion engines offer a promising solution for reducing NOx and PM emissions, but in turn, the lower temperature interferes with the diesel oxidation catalyst (DOC) causing an increase in CO and hydrocarbon emissions. To combat this, the development of new catalysts is critical. Recent studies by Song et. all show that a Pd/Cu alloy could lead to inhibition-free low temperature oxidation reactions. By modifying a python modeling package, Surface EP, a number of variations of Pd/Cu surfaces can be predicted quickly and with relative accuracy. The program develops a three by three surface cell and can test for binding energies with Oxygen at the three possible site locations (Top, Bridge, and Hollow). These variations are then screened for the best possible matches. Further testing can then be conducted for additional binding energies in the oxidation reaction using Density Functional Theory (DFT) calculations.