Collaborative Research: EAGER: Insights into the Hydrogen Evolution Reaction of Transition Metal Dichalcogenide Nanocrystals by In-situ Electron Paramagnetic Resonance Spectroscopy

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The large-scale deployment of hydrogen (H2) as a clean-energy fuel and chemical precursor will require replacing expensive platinum-group metals that catalyze the electrochemical splitting of water via the hydrogen evolution reaction (HER) utilizing renewable electricity. Previous research has identified a class of earth-abundant transition-metal dichalcogenide (TMD) nanocrystalline (NC) electrocatalytic materials that show great promise for the HER. The project will enable further advances in TMD-NC technology by employing a combination of in-situ analytical techniques coupled with theoretical calculations that will provide precise knowledge and understanding of the active catalytic sites in TMD NCs. Together with corresponding mechanistic understanding of the HER, the project will pave the way for the discovery and design of more efficient and less costly HER catalysts, thereby enabling the hydrogen economy. More broadly, the project includes educational, outreach, and workforce training initiatives supporting sustainable technologies for renewable energy and advanced catalysts. The overarching goal of this collaborative Early-concept Grants for Exploratory Research (EAGER) project is to establish an atomic-scale holistic understanding of the interplay between the structure, chemistry, catalytic activity, and mechanisms of the HER on 2H-MoS2 NC catalysts in real time. The team will accomplish this by employing a combination of in-situ electron paramagnetic resonance (EPR) spectroscopy and in-situ x-ray probes coupled with density functional theory (DFT) calculations. EPR spectroscopy will sensitively probe the local environment of paramagnetic catalytic sites, as well as their behavior in catalytic redox processes, under a wide range of operating conditions. In-situ x-ray techniques, complementary to in-situ EPR spectroscopy, will be employed to probe for the non-magnetic (i.e., non-EPR active species and other non-spin related factors) catalytically active HER species, and will enable the separation of the paramagnetic/spin effect from the overall catalytic activity. The changes in the EPR spectral properties, such as signal shape, width, intensity, and g-factor (Zeeman splitting) as a function of potential bias, time, and temperature, will be correlated with the measured HER activities to achieve the central goals of the proposal. DFT calculations will clearly identify the magnetic states of HER-active defect centers, correlate these magnetic states with the local environment of the defect, and calculate corresponding EPR spectra, taking into account the role of adsorbates, electrode polarization, and solvent screening. The outcomes of this research will resolve key challenges in understanding the catalytic activity of TMDs and provide fundamental insights that enable rational design of TMD-based electrocatalysts. Beyond the immediate focus on TMD electrocatalysis, the project will advance in-situ EPR as a promising tool for catalysis science. From the broader impacts perspective, the project will train the Hispanic student population (82%) at the University of Texas at El Paso in renewable energy research. Project-related educational material will be integrated with several outreach activities geared towards broadening participation of army personal and veterans at Fort Bliss in the El Paso region in scientific research. Educational modules on catalysis and its role in renewable energy will be developed and delivered at the University of Massachusetts, Amherst as part of the annual professional development workshops for K-12 STEM educators.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.