Fundamental Surface Properties and Gas-Surface Interactions of Two-Dimensional Materials

• Main Author: Nayakasinghe, Mindika Tilan Abeyrathna
• Format: Others
• Published: North Dakota State University 2019
• Online Access: https://hdl.handle.net/10365/29325

Heterogeneous model catalysis with supported nanomaterials on ultra-thin two-dimensional films has contributed significantly to improve the existing industrial catalytic processes, as well as to discover novel ways to enhance selectivity, specificity, and stability of the catalysts. Silica and zeolites are of particular interest, which has been widely utilized as catalysts and catalytic supports in several industrial processes. However, there are a limited number of surface science studies with zeolites due to the lack of surface analogs. Understanding the fundamental surface properties of silica and zeolites, involving the synthesis of surface analogs of silica and zeolites, characterization, surface modification, and screening for chemical and physical properties connected to the heterogeneous catalysis related applications utilizing advanced ultra-high vacuum-based surface science techniques is the main focus of this dissertation. Catalyst particles should be finely distributed on high surface area supports, in order to have high selectivity and specificity. Particle agglomeration during extreme catalyst operation (reaction) conditions decreases the efficiency of the catalysts over time. One common strategy to address the issue of particle agglomeration is to promote strong catalyst-support interactions. In this study, chemical reactivity of the inert silica was improved by doping with aluminum, which enhanced the polarity of silica (2D-zeolites) and hence the catalyst-support interactions compared to inert silica. Organohalide perovskite thin films are a fascinating class of material, which attract much attention in the recent past as the light harvesting materials in solar cells due to excellent power conversion efficiencies. However, poor thermal, chemical, and long-term stability limit the industrial applications of these organohalide perovskites. Gas-surface interactions on methylammonium lead iodide perovskite thin films were investigated in order to understand the thermal and the chemical degradation mechanisms utilizing UHV-based surface analytical techniques combined with computational calculations. Thermal stability improvement of the perovskite thin films by surface passivation using a protective chemical inhibition layer was successfully investigated experimentally. === ACS-PRF === North Dakota State University. Department of Chemistry and Biochemistry === North Dakota State University. Research and Creative Activity