My research interests lie within the broad umbrella of chemical physics, with emphasis on chemical vapor deposition and reaction kinetics. A common strand of my current and future research interest is develop and use analysis methods in order to understand reaction mechanism both in the gas-phase and at the surface. My research statement is organized into two parts, in the first part; I will briefly describe major fields of experience that have been gained throughout my graduate research. In the second part, future research plans are summarized and related to experience.
Current research interests
The production of silicon carbides (SiC) using catalytic chemical vapor deposition (Cat-CVD) has gained more attention in recent years. SiC have found their ways into many applications in microelectronics, the nuclear industry, and in solar cells as window layers. In addition to conventional open-chain alkylsilanes, a new generation of Cat-CVD precursors, silacyclobutanes (SCB’s), has been proposed. SCB’s are characterized of their high-ring strain that enhances their decomposition on the hot filament, which has a direct impact on the Cat-CVD efficiency. Although current efforts are geared towards the properties of the final stage of the production, i.e. the thin films, the gas-phase reactions responsible for the deposition process are still poorly understood. My PhD. project aimed towards investigating two SCB’s, namely,1-methyl-1-silacyclobutane (MSCB) and 1,3-disilacyclobutane (DSCB). MSCB has been carefully chosen because it has a unique structure that contains both Si-H and Si- CH3 bonds, while DSCB was chosen due to its unique structure that has a built-in Si:C ratio of 1:1, that matches the one in SiC’s. In addition, DSCB has four relatively-weak Si-H bonds that makes it a promising precursor for hydrogenated SiC’s (SiC:H). The latter has important applications in the solar cells industry. in order to outline a comprehensive decomposition mechanism for both compounds.
In order to implement the SCBs mentioned above in Cat-CVD industrial reactors, their reaction kinetics need to be understood. In my late stages of my PhD. work, I have designed a project to study the gas-phase kinetics of MSCB and DSCB on the hot-wire. The Cat-CVD gas-phase chemistry is a complex one, since it involves reactions on the surface. I combined my analytical skills together with my knowledge of laser ionization techniques to construct an effective procedure that tackled this complicity of these reactions.
Throughout my PhD. study, I became fascinated with what quantum calculations can do. Theoretical calculations is often used to verify, validate, strengthen, and compare against experimental results. In some occasions, the use quantum chemical calculations become spinal rather than optional, as calculations can simulate experimentally impossible situations, such like depicting transition states and intermediates. Although it was not one of my original PhD. proposal, I have developed my skills in theoretical quantum calculations and used them to explore the gas-phase decomposition of MSCB and DSCB. Both studies have been published in reputable journals.
In the course of the Cat-CVD process, the metal filament play the role of the catalyst. It was experimentally proven that the precursor decomposition is catalyzed on the metal filament surface when it is compared to conventional thermal pyrolysis. Aging (poising) of the filament during the Cat-CVD process is considered one its major drawbacks. In my PhD. project, I investigated the aging of both tungsten and tantalum filaments using MSCB and DSCB. The study was done by systematically subjecting the filaments to the gas precursors at different conditions of temperature and deposition times. The study successfully optimized the best conditions for minimum aging in order to extend the filament’s lifetime. Interestingly, my filament aging project revealed the formation of highly crystalline materials resulted from the gas precursor reaction with the solid filament. Examples of this materials are tungsten carbide and silicon carbide, both have high value in the industry.
For my future research, I foresee the following directions:
Two major alternative energy research areas are fuel cells, and solar cells. Fuel cells are considered novel, environmentally friendly, and energy efficient. Nanoparticles of metaloxides with size of few nanometers that serve as electrocatalysts for H2, Methanol, or ethanol oxidation are in center of attention. Optimizing the properties of such nano materials is crucial for the development of low-temperature Proton Exchange Membrane Fuel Cells (PEMFs). Meanwhile, solar cells are considered advantageous because of their lower CO2 emission, safety, and mobility.
For centuries, nature has inspired researchers to develop a photoelectrochemical cell that mimics photosynthesis, and combine the fuel and the solar cell in one. In this type of cell, water is split into oxygen and protons (eventually H2), which then can be utilized as a fuel. A straightforward idea to use the most abundant earth resources - water and sun - to shape the future of energy demand. In - what is called - artificial photosynthesis, different types of photocatalysis are being developed. Among many, biocatalysis (enzymes), redox catalysis, transition metals, metal oxides, and metal-organic frameworks (MOFs) are some examples. My interest is to optimize the parameters controlling the catalyst activity, in order to maximize its light harvesting capability and increase its efficiency. Since most of the sunlight reached by the earth surface falls in the visible spectrum, my goal is to design catalysis that absorbs in that region. I will use my expertise in spectroscopy, scanning electron microscopy (SEM), Auger electron spectroscopy (AES), XRD, and electrochemical techniques like voltammetry in this research.
With the exponential growth of human activity and population, wastewater became one of the major challenges we face nowadays. From the perspective of sustainability, managing water resources and its waste becomes crucial. One novel area of research is to develop metal oxide nanoparticles that effectively adsorbs heavy metals found in waste water. My interest is to investigate the adsorption mechanism and the kinetics of the process, in order to maximize the nanoadsorbents efficiency. Some parameters to investigate are: the nanoadsorbent material and size, the type of adsorption isotherm, the type of solvent, the medium acidity, and temperature, In addition, understanding the thermodynamics and the rate at which the process occurs is critical to understand the adsorption process.
Quantum theoretical calculations became widely used to comprehend, analyze, and simulate chemical reactions. In my future research, I will use theoretical calculations to understand the reaction mechanisms of the catalysis described above; either the photoelectrochemical or the nanoadsorbents.
The field of theoretical calculations requires solid understanding of quantum chemistry, mathematics, and programming. My goal is to help my students progress in these fields in order to carry out efficient and reliable theoretical calculations. Since the interpretation of theoretical calculation outputs require solid knowledge in other aspects of chemistry, i.e. organic, physical, and inorganic. My aim is to help the students link the different fields in order to better understand their calculation results.