Atomically Dispersed Metal Catalysts for Electrochemical Hydrogen Evolution

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Professor Shaowei Chen of the University of California-Santa Cruz is supported by the Chemical Catalysis Program of the Division of Chemistry to investigate the use of individual metal atoms embedded within a carbon matrix as a new catalytic material for the industrially important hydrogen evolution reaction. Embedding metal on the atomic scale represents full utilization of the catalytic material and affords maximal interactions with the supporting carbon substrate. This provides an option for deliberate manipulation of the electronic properties of the metal atoms and hence the electrocatalytic activity of the catalyst. The hydrogen evolution reaction is a critical process in water electrolysis for the generation of hydrogen, a clean and sustainable energy source. Platinum-based nanoparticles have been used extensively as the catalysts of choice for this reaction. Yet the high costs and limited natural reserves of platinum have greatly hampered the wide-spread application of such electrochemical technologies. Thus, it is of both fundamental and technological significance to develop viable alternative electrocatalysts that are of low-cost and high-performance. The project offers an opportunity for students to be trained in an interdisciplinary research environment in renewable energy research. Project-related educational material is integrated with several outreach activities geared towards broadening participation of women, undergraduate and high school students in scientific research. The goal of this project is to develop effective strategies for the preparation of high-performance single atom catalysts (SACs) for the hydrogen evolution reaction (HER) in alkaline media. HER is a critical process in electrochemical water splitting to generate hydrogen, a clean and sustainable energy source. The project is primarily motivated by a recent breakthrough in the laboratory of the principle investigator, where ruthenium single atom catalysts embedded within nitrogen-doped carbon are found to even outperform platinum in alkaline HER. To further enhance the electrocatalytic activity, the proposed research will focus on the following tasks: (i) maximization of Ruthenium SAC concentration by thermal engineering of the catalysts; (ii) preparation of SACs with other metals, such as Iridium, Rhodium, and Palladium; and (iii) preparation of bimetallic SACs with the initial focus on Ruthenium and Gold. A suite of analytical surface techniques is used to characterize the catalytic materials. Theoretical modeling and simulations based on density functional theory calculations with structural models relevant to experimental data are carried out in parallel so as to unravel the atomic sites that are responsible for the HER electrocatalytic activity and aid in catalyst design, structural engineering, and ultimately, catalyst optimization. It is anticipated that the project outcome may facilitate the rational design and engineering of effective SACs that rival commercial platinum/carbon catalysts.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.