(366ak) Advancing Semiconductor and Catalyst Technologies through Atomic-Scale Modeling

Abstract

My research focuses on the computational study of the growth mechanisms in group IV semiconductors. Semiconductor materials comprising Group IV elements (Si, Ge, and/or Sn) have demonstrated promising optoelectronic properties, positioning them as candidates for next-generation low-temperature optical computing and communications technologies. However, the development of devices utilizing these elements has been limited by challenges in efficiently incorporating Sn, which is required to tune the band structure for direct transitions, in high-quality and uniform materials. Utilizing Density Functional Theory (DFT) calculations, we aim to elucidate the atomic-scale processes that govern the nucleation, growth, and stability of group IV semiconductors. Our interest lies in understanding the influence of various synthesis protocols, surface passivations, and strain engineering on the electronic properties and structural stability of materials including Si, Ge, Sn, and GeSn alloys. We explore the effects of hydrogenation, halogenation, and alkylation on these materials to enhance their optoelectronic performance and integrate them into next-generation electronic devices.

In the realm of heterogeneous catalysis, our research investigates active sites and reaction pathways on catalyst surfaces to optimize efficiency and selectivity for industrially relevant chemical transformations. By combining experimental and theoretical characterization, we identify the structures of active sites and model the interaction of reactants with these active sites. This approach seeks to uncover key factors that enhance catalytic activity and longevity. Our work bridges the gap between experimental observations and theoretical predictions, guiding the design of novel materials with superior performance.

In particular, we explore the catalytic properties of metal single-atom catalysts (SACs) dispersed on graphene for applications in lithium-sulfur (Li-S) batteries and hydrogenolysis reactions. We analyze the interaction between various single metal atoms and reactants, focusing on binding energies, electronic structures, and charge transfer characteristics. For Li-S batteries, our findings suggest that specific metal SACs on graphene, such as Ti, V, and Nb, can enhance sulfur adsorption and support electrochemical reactions, leading to improved battery performance and longevity. In hydrogenolysis reactions, Fe SACs demonstrate significant catalytic activity, offering the potential for efficient and selective cleavage of C-H and C-C bonds. This comprehensive study provides valuable insights into the design and optimization of metal single-atom catalysts on graphene for energy storage and catalytic applications.

In another study, we investigate the positive effect of water on cracking reactions in confined surface of H-ZSM5 zeolite, a widely used catalyst in the petrochemical industry. Using a combination of experimental techniques and computational modeling, we examine how the presence of water influences the structure and catalytic activity of H-ZSM5 during hydrocarbon cracking. Our results reveal that water plays a crucial role in enhancing catalytic performance by facilitating the formation of extra-framework species, which induce dipole-dipole interactions with the transition states, stabilizing them and lowering activation barriers. This study provides new insights into the mechanism of water-assisted cracking in H-ZSM5 zeolite, offering potential strategies for optimizing different extra-framework species in zeolite catalyst design.

This interdisciplinary research integrates principles from materials science, chemistry, and physics, contributing to the development of advanced materials for sustainable energy solutions and electronic applications. Our findings are expected to pave the way for innovative approaches in semiconductor manufacturing and catalyst design, ultimately advancing technology in these critical fields