My research interests lie broadly within physical chemistry, with an emphasis on reaction mechanisms and kinetics. As a chemist, I believe that developing an understanding of chemical reactions at the molecular level is crucial in the optimization of industrial processes. A common strand among my current and future research interests is to find solutions for environmental and industrial problems through an improved understanding of their associated chemical reactions. This research statement includes both current and previous fields of interest.

Current research interests

1. Sustainable Production of Ammonia

Ammonia is the second most produced chemical worldwide after sulfuric acid. 80% of ammonia production is utilized in the fertilizer industry. As the world population increases, demand for ammonia is expected to increase rapidly. Furthermore, ammonia is considered to be a promising fuel due to its high energy content and lack of CO₂ emissions. Liquid ammonia can be readily transported over long distances, unlike gaseous fuels. Ammonia also avoids the high energy demands of liquefaction and boil-off losses of liquid hydrogen. Currently, ammonia is mainly produced by the conventional Haber process from nitrogen and hydrogen. The process depends on natural gas to obtain H₂. In addition, the process is costly, energy intensive, and has low efficiency.

Because the future of the world economy requires developing new and diverse renewable energy sources, my research is currently focused on developing a new generation of catalysis for ammonia production. The process involves using non-fossil fuel resources (like water to produce H₂), uses less energy, and avoids CO₂ emissions. In addition, my research explores new avenues for producing ammonia from wastewater, and from nitrogen-containing pharmaceutical wastes in particular.

2. Industrial Wastewater Treatment, adsorption and photocatalytic degradation

With the world’s population increasing exponentially, wastewater management has become an increasingly pressing concern. Among the many treatment technologies currently under research, adsorption of wastewater contaminants and heavy metals using metal oxide nanoparticles has proved to be an effective methodology. However, optimizing this process requires a deeper understanding of the chemistry, reaction kinetics, and thermodynamics of adsorption. Instead of employing a “trial and error” approach, my current efforts focus on understanding the parameters affecting adsorption using both experimental and theoretical techniques. For example, by determining the rates of diffusion, adsorption, and desorption for a given adsorbate/adsorbent pair, the process of removal of containments from wastewater can be better controlled, leading to improved efficiencies.

The presence of pharmaceuticals in wastewater is another emerging problem. Photodegradation is known to be an efficient and sustainable method to treat these wastes. However, this technology faces several challenges, such as the high electronic band gap of the photocatalyst and the lack of an efficient industrial process. My current interests lie in developing a new generation of photocatalytic reactors. These reactors function using the visible spectrum of solar energy, and using less energy than conventional UV light sources. This work also involves the development of a new hybrid metal oxides photocatalysts. These are nano-scaled materials that are coupled to other types of semiconductors. One example is titanium oxide (TiO₂) coupled to cadmium sulfide (CdS), tin oxide (SnO₂), or tungsten oxide (WO₃).

As a chemist, I aim to use my skills in inorganic synthesis, chromatography, spectrometry, and ab initio calculations to understand the parameters affecting the chemistry of photodegradation. My long term goal is to introduce a full integrated photocatalytic process that can be applied at an industrial scale.

3. Quantum Mechanical Calculations

Theoretical calculations are often used to verify, validate, strengthen, and compare against experimental results. In some instances, the use of quantum mechanical calculations is the only means of studying a system, such as the study of transition states and intermediates. Recently, my theoretical work on chemical structures that mimic asphaltene helped establish an understanding of their thermal oxidation chemistry. This was achieved by comparing the calculated kinetics parameters (activation energies and pre exponential factors) and the thermochemical values (energies of reaction) to those obtained from the experiment. The importance of such studies allowed me to identify the reaction pathways that govern the oxidation process.

Similar efforts are currently concentrated on establishing the reaction mechanisms governing the degradation of dyes, pharmaceuticals, and heavy oil residues.

4. Physical chemistry and theoretical calculations education

In the last few decades, there has been a dramatic growth in research that utilizes theoretical calculations. The scientific literature is currently overwhelmed with research papers that covers topics in the field of ab initio calculations, molecular dynamics modeling, and chemical process simulations. Unfortunately, the misuse of theoretical calculations due to lack of knowledge, inconsistency, or false input parameters, has led to untrustworthy outcomes. Therefore, I feel it is my obligation to train my students to rigorously and appropriately apply their calculations in their scientific analyses. It is my belief that performing quantum theoretical calculations requires a solid foundation in chemistry, quantum mechanics, programming, and calculus.

Finally, since the interpretation of theoretical calculation outputs requires knowledge of other aspects of chemistry, i.e., organic, physical, and inorganic, my aim is to direct students to draw conclusions from their calculations that make chemical sense, rather than speculations.

Previous/other research interests

1. Catalytic Chemical Vapor Deposition (Cat-CVD)

The production of silicon carbides (SiC) using catalytic chemical vapor deposition (Cat-CVD) has gained more attention in recent years. SiC are found in 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 (SCBs), has been proposed. SCBs are characterized by their high ring strain that enhances their decomposition on hot filaments, which has a direct impact on the Cat-CVD efficiency. Although current efforts are aimed towards the properties of the final stage of the production, i.e., thin films, the gas-phase reactions responsible for the deposition process are poorly understood. My PhD project investigated two SCBs, namely, 1-methyl-1-silacyclobutane (MSCB) and 1,3-disilacyclobutane (DSCB). MSCB was chosen due to its unique structure containing both Si-H and Si-CH₃ bonds, while DSCB was chosen due to its unique structure that has a Si:C ratio of 1:1, which is the same for SiC. In addition, DSCB has four relatively-weak Si-H bonds that makes it a promising precursor for hydrogenated SiC (SiC:H). The latter has important applications in the solar cells industry. Specificity, for constructing the window-layer in the solar cell.

2. Metal-filaments aging and crystalline material formation

As described above, the metal filament plays the role of the catalyst in the Cat-CVD process. However, the catalytic nature of the filament is associated with its aging. Filament aging (or poisoning) is one of the major drawbacks of the Cat-CVD process. Because of aging, the filament loses its catalytic activity and need to be replaced more often.

In my PhD project, I investigated the aging of both tungsten and tantalum filaments using MSCB and DSCB. The study was done by subjecting the filaments to gas precursors at different temperatures and deposition times. The study successfully optimized the best conditions for minimum aging in order to extend the filament 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 of which have high value in industry.

3. Alternative energy research, photoelectrochemical cells

Two major alternative energy research areas are fuel cells and solar cells. Fuel cells are considered novel, environmentally friendly, and energy efficient. Nanoparticles of metal oxides with a size of a few nanometers serve as electrocatalysts for H₂, methanol, or ethanol. Optimizing the properties of such nanomaterials is crucial for the development of low-temperature Proton Exchange Membrane Fuel Cells (PEMFs). These are promising types of fuel cells that are expected to replace the aging alkaline fuel-cell.

Meanwhile, solar cells are considered other types of renewable energy sources. Their advantages include low CO₂ emissions, safety, and mobility.

For centuries, nature has inspired researchers to develop a photoelectrochemical cell that mimics photosynthesis and combines the fuel and the solar cell into a single system. In this type of cell, water is split into oxygen and protons (eventually H₂), which can then be utilized as a fuel. In artificial photosynthesis, different types of photocatalysts are being developed, including biocatalysts (enzymes), redox catalysts, transition metals, metal oxides, and metal-organic frameworks (MOFs). My interest is to optimize the parameters controlling visible light spectrum catalyst activities in order to maximize their light harvesting capabilities and increase their efficiency. I will use my expertise in spectroscopy, scanning electron microscopy (SEM), Auger electron spectroscopy (AES), XRD, and electrochemical techniques like voltammetry in this research.