Mechanistic Insights into Covalent and Ionic Contributions to Molecular Adsorption and Reaction on Transition Metals

University Of Akron, Akron OH

Investigators

Abstract

Catalysis is a process in which one chemical substance provides a new and easier pathway for reactant (feedstock) chemicals to produce more desirable products. Catalytic chemicals can greatly enhance the reaction rates, which allows the reactions to proceed under milder and more controllable conditions, and improves the selectivity to the desired product (fewer by-products). Currently, developing a good catalyst for a specific, desirable reaction is challenging and requires good knowledge of how the reactants and catalyst interact. In this project, Dr. Zhenmeng Peng is researching the key factors that determine reactant-catalyst interactions for transition metals in carbon monoxide (CO) oxidation catalysis. Dr. Peng's approach is to improve upon an adsorption model for accurate calculation of these interactions from easy to perform measurements. Knowledge gained in this research helps to significantly accelerate the search for new catalysts. Catalysis plays an essential role in chemical, petrochemical and energy industries, with catalytic materials being widely used for chemical conversions and energy generation, and thus the research has broad societal impact. Dr. Peng is also actively engaged in a number of outreach activities, aimed at creating early scientific interest in high school students and influencing their career development in science, technology, engineering and mathematics (STEM) fields. He is involved in the development of a nanocatalysis learning module for K-12 teachers, mentoring of undergraduate and graduate students, development of a community learning network course, and diversity outreach efforts with Women in Engineering (WIE) and Increasing Diversity in Engineering Academics (IDEA) programs at the University of Akron. THe also mentors undergraduate and graduate students, preparing them for future careers in areas that require chemistry and engineering knowledge. With funding from the Chemical Catalysis Program of the Chemistry Division, Dr. Zhenmeng Peng at the University of Akron is developing an improved model of d-band theory of adsorption energy (Ead) using readily-measured catalyst parameters. He is using a multi-approach mechanistic study of carbon monoxide oxidation to test this improvement. To this aim, Dr. Peng is synthesizing model catalysts with a controlled d-band center and work function parameters and examining their correlations with CO and O2 adsorption. The research employs Ead of the reacting species to obtain information on the reaction mechanism and other important catalytic properties which are challenging to measure experimentally. Establishing an exact Ead-catalyst parameter relationship allows Dr. Peng to characterize adsorbate and reactive intermediate bonding to the metal substrate, the knowledge of which helps to understand the catalytic mechanism, identify reactive intermediates, and guide catalyst research. Driven by the hypothesis that implicit inclusion of both covalent and ionic contributions to d-band theory can significantly improve the accuracy of the theory, Dr. Peng relates the metal d-band center and work function to Ead for inclusion of the covalent and ionic fractions, respectively. Knowledge gained in this research helps to significantly accelerate the search for new catalysts. Catalysis plays an essential role in chemical, petrochemical and energy industries, with catalytic materials being widely used for chemicals conversion and energy generation, and thus the research has broad societal impact. Dr. Peng is actively engaged in a number of outreach activities, in support of the broader impacts of the project, to educate students and improve the public interest in chemistry knowledge and technology. K-12 students and underrepresented minority students are particularly targeted in the outreach activities.