NSF-BSF: Controlling Phase Selectivity and Electrocatalytic Activity of Transition-Metal Dichalcogenide Overlayers in Core-Shell Nanoparticles for CO2 Reduction

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The discovery and optimization of inexpensive catalyst materials is fundamental to fulfilling the urgent need for clean and sustainable sources of energy. In particular, conversion of carbon dioxide (CO2) to valuable chemical feedstocks and fuels, when complemented by renewable sources of energy, offers a promising route for sustainable management of carbon emissions, but the process is currently inefficient due to the lack of suitable catalysts. To address this challenge, this project, funded under the National Science Foundation (NSF) and US-Israel Binational Science Foundation (BSF) collaborative opportunity NSF 17-520, will support investigation of a new class of catalysts that enable the efficient conversion of CO2 to higher-value chemicals and fuels. A team of researchers from the University of Massachusetts Amherst and Ben Gurion University will analyze and evaluate catalysts that are engineered from materials that are abundant in the Earth's crust and inexpensive to process at large scales. The broader societal impacts of this project include recruitment and mentoring of underrepresented minority students at UMass Amherst, and outreach to the communities in Western Massachusetts and Israel. US-Israel scientific collaboration will be enhanced by graduate student exchanges between the partner institutions.Electrochemical reduction of CO2 is a promising avenue for closing the carbon cycle but is stymied at present by the lack of catalysts that are both active and selective at low overpotentials. This project focuses on earth-abundant electrocatalysts, based on semi-metallic phases of the molybdenum (Mo) and tungsten (W) family of layered transition-metal dichalcogenides (TMDCs), with the goal of addressing these demanding catalytic performance requirements. An integrated theory-synthesis-characterization approach facilitates rational design of transition-metal core-TMDC shell nanoparticles in which the electrochemically-active, semi-metallic phases of Mo and W TMDCs are preferentially stabilized over the ground-state, semiconducting phases. In particular, stabilization of the semi-metallic phases does not rely on conventional kinetic trapping approaches, being achieved instead by charge-transfer interactions between the metallic cores and the TMDC shells, which provides a greater degree of robustness against the undesirable semimetal-to-semiconductor phase transition. Fundamental advances in the development of such phase-engineered, core-shell nanoparticles project far-reaching scientific impact in the fields of two-dimensional materials and nanoscale catalysis, while also enabling renewable energy technologies. The research program is integrated with formative research opportunities for undergraduates from minority-serving institutions thereby nurturing the next generation of materials scientists and engineers. Presentations to the students and the broader public in Western Massachusetts and Israel on issues associated with nanotechnology and its applications in renewable energy further extend the impact of this research. US-Israel scientific collaboration will be enhanced by personnel exchanges between partner institutions.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.