(6bn) Discovery and Optimization of Processes and Catalysts for the Organic Electrosynthesis of Carbon-Neutral Fuels and Chemicals
AIChE Annual Meeting
Sunday, November 10, 2019 - 1:00pm to 3:00pm
The electrochemical reduction of carbon dioxide (CO2) offers a potential means for synthesizing carbon-neutral fuels and chemicals using intermittent renewable electricity. Unfortunately, the state-of-the-art electrocatalysts for CO2 reduction are neither active nor selective enough to make the process commercially viable. Additionally, research efforts aimed at discovering novel electrocatalysts with superior activity or selectivity compared to pure metallic Cu have failed to identify promising candidates. My research activities to date have sought to alleviate this issue.
I investigated many different aspects of the electrochemical CO2 reduction reaction during my doctoral studies under the guidance of Prof. Alexis. T. Bell at the University of California at Berkeley. These research efforts were focused on the development of analytical instruments, the elucidation of reaction mechanisms, the establishment of structure-activity relationships, and the discovery of novel electrocatalysts. I developed an analytical instrument capable of quantifying the composition of the local reaction environment in the immediate vicinity of the electrocatalyst by sputter depositing it directly onto a pervaporation membrane that was coupled to a mass spectrometer. Using this approach, I observed a surprisingly high abundance of multi-carbon aldehydes relative to alcohols within the local reaction environment while conducting CO2 reduction over Cu. This observation led to the hypothesis that primary aldehydes are intermediates to the corresponding primary alcohols during CO2 reduction over Cu. Furthermore, I discovered that the reduction of these aldehyde intermediates could be suppressed by introducing small amounts of Ag into the Cu surface by Galvanic exchange. The incorporation of relatively large Ag atoms into the Cu surface produces compressive surface strain that inhibits the ability of Cu to reduce these aldehyde intermediates further by reducing its oxophilicity and the steady-state coverage of adsorbed H.
I have begun to develop electrocatalysts for hydrocarbon and alcohol evolution beyond Cu since beginning my postdoctoral research under the guidance of Prof. Ib Chorkendorff at the Technical University of Denmark. Thus far, I have developed a rational protocol for designing Cu-free intermetallic electrocatalysts that utilizes the d-band valence electronic structure of the electrocatalyst as the descriptor of electrocatalytic activity. The d-band valence electronic structure of a transition metal determines its binding energies for reactive chemical species. Unsurprisingly, the d-band valence electronic structure of Cu is highly unique. I have demonstrated that the d-band valence electronic structure of a transition metal can be systematically modified to resemble Cu via the formation of strong intermetallic bonds with electronically dissimilar metals. Furthermore, I have demonstrated that composition gradients form in the near-surface region of such intermetallic alloys upon air exposure using both x-ray photoelectron and ion scattering spectroscopies. These previously unidentified near-surface composition gradients cast doubts on the conclusions drawn from prior studies of CO2 reduction over similar intermetallic electrocatalysts and potentially explains the lack of promising alternatives to Cu. Finally, I have developed a novel experimental methodology that prevents the formation of these near-surface composition gradients.
Future Research Interests:
My future research interest is to discover and optimize processes and catalysts for the organic electrosynthesis of carbon-neutral fuels and chemicals. Beyond the reduction of CO and CO2, I am interested in investigating the partial oxidation of chemicals derived from natural gas (such as methane and ethane), the selective reduction of biomass-derived platform molecules (such as furfural and levulinic acid), and the upgrading of organic molecules via electrochemical carbonylation. I am interested in establishing the structure-activity relationships for these reactions and using them to conduct hypothesis-driven electrocatalyst discovery. Concurrently, I will utilize a combination of mass spectrometry and infrared spectroscopy to elucidate reaction mechanisms. Finally, I will also design and validate working devices to bridge the gap between fundamental science and commercial implementation.
I have a strong interest in sharing my passion for science with others, both in the classroom and in the laboratory. I was the founding president of the Renewable Energy and Energy Efficiency Club (RE3) during my undergraduate studies. This club combined stimulating lectures from local academic and industry experts with hands on projects designed to cultivate student interest in renewable energy and energy efficiency technologies. During my doctoral studies I served as a graduate student instructor for courses on transport and separations processes and chemical process design. Furthermore, I volunteered with Students for Environmental Energy Development, an organization that aims to attract high school students into STEM careers through self directed research projects. I have also mentored 4 undergraduates and 2 masters students through academic research projects. Several of these students become co-authors of published manuscripts for their intellectual contributions and have since gone on to pursue doctoral degrees on their own. Finally, I have recently co-authored a textbook chapter on the fundamentals of heterogeneously catalyzed electrochemical CO2 reduction in order to increase the breadth of my impact further. As a classroom educator, I am interested in teaching students the fundamentals of thermodynamics, kinetics, and transport phenomenon and how they can be employed to tackle challenging real world problems. Furthermore, I am interested in developing new courses that cover material more closely aligned with my research interests, such as electrochemistry, catalysis, and emerging energy technologies.