(3bl) Design of Advanced Catalytic Systems Through Computational Methods

Catalysts are materials pervasive to many areas such as petroleum refining, fuel cell technology, hydrogen production, fine synthesis, food processing, and pollutant elimination, among others.  Catalysts typically work at the nanoscale, which creates huge opportunities to design application-driven new catalytic systems through rational manipulation and design of nanoscale structures.   On the other hand, recent advancements in computation have solidified molecular simulations and computational chemistry as powerful tools to investigate phenomena at the nanoscale, and to design materials using a bottom-up approach. 

As a materials scientist possessing an expertise in molecular simulation, my research interests encompasses the utilization of simulation methods such as density functional theory (DFT), molecular dynamics (MD), and multiscale methods to the design of advanced catalytic systems for: 1) Synthesis of advanced materials (e.g. synthesis of single-walled carbon nanotubes (SWCNTs)), 2) Energy-efficient (e.g. photocatalysis) synthesis of chemical compounds, 3) Synthesis of alternative fuels (e.g. hydrogen), and 4) bio-inspired heterogeneous catalysis.  In planning my research I always consider the experimental component that in a multidisciplinary context I expect from multiple collaborations at the departmental, college, and other institutions levels. 

Here I show research performed during my doctoral studies in the Materials Science & Engineering Program at Texas A&M University, under the supervision of Dr. Perla Balbuena in the Artie McFerrin Chemical Engineering Department.  I focus on the design of a catalytic system for the chiral-selective synthesis of SWCNTs.  The chiral-dependent electronic and optical properties of SWCNTs promise to revolutionize the fabrication of power-efficient electronic devices, and ultrasensitive bio- and chemo-sensors, as well as introduce new diagnosis and therapeutic strategies.  However, with the availability of commercial quantities of nanotubes of predetermined properties as a prerequisite for the exploitation of these technologies, the need for chiral-selective nanotube synthesis is evident. 

Using the interaction of the dispersed catalyst nanoparticles with the support as a means of controlling the nanoparticle structure/dynamics we examine the conditions to create a template effect that helps guide the nanotube growth toward a desired chirality.   Using molecular simulation we investigate the mechanism that establishes a correlation between the nanoparticle and nanotube structures, and the impact of nanoparticle size and strength of interaction with the support on the template effect effectiveness. We have found that this effectiveness is affected, because the latter factors affect the rate of defect annealing, nanoparticle/nanoparticle contact, the heterogeneity of the nanoparticle surface, and the mobility of the nanoparticle.  We have also obtained valuable information about the nanotube growth mechanism, and examined the implications for chirality control and the accuracy of the vapor-liquid-solid (VLS) mechanism to describe nanotube growth.