CBE Seminar: New Generation Electrocatalysts for Fuel Cells
Department of Chemical and Biomolecular Engineering
University of California, Irvine
Abstract: Platinum Group Metal-free (PGM-free) catalysts have been extensively developed for both Proton Exchange Membrane (PEM) and Alkaline Exchange Membrane (AEM) fuel cells, aimed at automotive, stationary and portable applications. In this lecture we will address the critical challenges that our team has faced on the way to practical application of such catalysts.
Over the last decade or so (while at the University of New Mexico), our team has developed the Sacrificial Support Method (SSM) as a main approach for templated synthesis of hierarchically structured electrocatalysts materials. In this method the catalysts precursors are being absorbed on, impregnated within or mechanically mixed with a support (usually mono-dispersed or meso-structured structured silica), thermally processed (pyrolyzed) and then the silica support is removed by etching to leave the open frame structure of a “self-supported” material that consists of the catalysts only.
The makeup and structure of the active site/sites of the PGM-free ORR electrocatalysts, including geometry (coordination) and chemistry (composition and oxidation state), remain contentious even after 50 years of research. There is an emerging agreement that iron and nitrogen functionalities, displayed on the surface of the carbonaceous substrate/support, govern ORR activity. This is often combined with a broadly accepted hypothesis that microporous surface area plays a critical role in forming the active site. Candidate structures participating in ORR include multitudes of nitrogen defect motifs in the carbon matrix of different degrees of graphitization, with metal incorporated as metal nanoparticles, corresponding (native) oxides and/or as atomically dispersed, oxidized metal species, linked (coordinated) to nitrogen defects in the carbonaceous matrix in a variety of possible configurations. This presentation will attempt to address the rational design and performance metrics of the M-N-C electrocatalyst based on a broad experimental set of data. Scientific and engineering technology challenges will be discussed in the context of maturation of Polymer Electrolyte Fuel Cells (PEMFC) and their market penetration.
This lecture will review the applications of this new class of electrocatalyst across several fuel cell applications: from automotive to microbial and from regenerative electrolyzer/fuel cell units to water purification and desalination devices. These catalysts also allowed broad introduction of state-of-the art electrochemical technology in microbial electrochemical devices: microbial fuel cells, bio-electrochemical electrolyzers and advanced water treatment technologies.
New/emerging directions for extending these material types to catalysis of CO2 electro-reduction and N2 low temperature, low pressure electro-reduction aiming potentially at electrochemical ammonia synthesis will be discussed as well.
T.Asset & P. Atanassov, Joule 4 (2020) 33-44
Bio: Atanassov graduated from the University of Sofia (1987) specializing in chemical physics and theoretical chemistry. He joined the Bulgarian Academy of Sciences (BAS) and become a member of the technical staff of its Central Laboratory of Electrochemical Power Sources (now the Institute for Electrochemistry & Power Systems). His initial work included materials solutions for metal-air batteries. He was a visiting scientist at the Frumkin’s Institute of Electrochemistry, in Moscow, Russia, studying bioelectrochemistry of enzymes, and received a Ph.D. in physical chemistry/electrochemistry from BAS.
Atanassov moved to the United States in 1992 and joined the research faculty at the University of New Mexico. During the 90s, he was involved in the development of several electrochemical biosensor technologies for biomedical, environmental, food safety and defense applications. In 1999, he joined Superior MicroPowders LLC (acquired later by Cabot Corp.), where he was a project leader in fuel cell electrocatalysts development and introduced spray pyrolysis for catalyst synthesis on an industrial scale. He returned to UNM in 2000 as a faculty member of the chemical & nuclear engineering department. In 2007, Atanassov founded the UNM Center for Emerging Energy Technologies (CEET). From January 2012 to December 2013, he was the associate dean for research of the UNM School of Engineering, and in July 2015, was promoted to a Distinguished Professor of chemical & biological engineering and chemistry & chemical biology. From January 2015 to September 2018, he served as director of the UNM Center for Micro-Engineered Materials (CMEM).
Atanassov joined UC Irvine in 2018, where he is a Chancellor’s Professor with the Henry Samueli School of Engineering, within the newly formed Department of Chemical & Biomolecular Engineering, holding secondary appointments with materials science & engineering and with chemistry. He is also affiliated with Los Alamos National Laboratory and is honorary professor of The Bulgarian Academy of Sciences. He served as a vice president of the International Society of Electrochemistry (2015-2017) and is a Fellow of the Electrochemical Society. In 2018, he was inducted in the National Academy of Inventors. In 2019, Atanassov received the ECS Energy Technology Division Award for his work on Platinum Group Metal-free (PGM-free) electrocatalysts.
Atanassov's materials for energy programs are focused on the development of novel electrocatalysts: non-platinum electrocatalyst for fuel cells, nanostructured catalysts for oxidation of complex fuels, and new materials and technologies for energy conversion and storage. His bioelectrocatalysis programs range from enzyme electrochemistry, enzymatic and microbial fuel cells, to systems for biological and bio-inspired energy harvesting. He was the lead/principal investigator on DOD-AFOSR MURI and DOE-EPSCoR New Mexico Implementation Award. His research programs have been funded by DOE-EERE and DOD-ARO, NSF and the Bill & Melinda Gates Foundation. He holds 50 issued U.S. patents, a substantial number of which have been licensed and are at the core of several catalyst products. He has published more than 400 peer-reviewed papers (bringing ~25K citations and forming an h-index of 78), 20 chapters in books, and edited a book on enzymatic fuel cells. Atanassov serves on the editorial board of ACS Applied Energy Materials, ChemElectroChem (Wiley-VCH) and Electrocatalysis (Springer). He served as an advisor for 35 completed Ph.D. dissertations at UNM and had advised a number of postdoctoral fellows.