CAS: Designing Efficient Electrocatalysts for Selective Reduction of CO2 to Carbon-Rich Products

With the support of Chemical Catalysis program in the Division of Chemistry, Drs. Manashi Nath (PI) and Julia Medvedeva (co-PI) from Missouri University of Science & Technology are designing new catalysts for the electrochemical reduction of carbon dioxide to value-added chemicals and fuels. The project aims to design efficient electrocatalyst compositions by combining an experimental- and computational-based approach that enhance CO2 reduction on the catalyst surface.

The project is further developing design principles for such catalysts derived from readily available and abundant metals. This multidisciplinary project involves undergraduate, graduate, and postdoctoral researchers collaborating on approaches involving chemistry, electrochemistry, physics, and surface science for the discovery of new catalyst compositions.

Knowledge generated from this project, falling under the broader scope of clean energy, will be disseminated to the scientific community at all levels employing various mechanisms including conference presentations, public seminars, peer-reviewed publications, and outreach activities. Specifically, demonstration experiments and workshops will be designed for local high school and middle school students by collaborating with a local STEM club, Kaleidoscope, which organizes after-school STEM activities.

Public awareness of carbon dioxide capture and conversion will be accomplished through outreach activities at the St. Louis Science Center, through Minority Introduction to Engineering (MITE) camps run by Missouri S&T, and through workshops organized during the summer for local high school teachers. These activities will include live demonstrations of an active CO2 electroreduction cell made by employing catalysts developed in this research project.

With the support of Chemical Catalysis program in the Division of Chemistry, Dr. Manashi Nath (PI) and Dr. Julia Medvedeva (co-PI) from Missouri University of Science & Technology are studying designing efficient catalyst composition for electroreduction of carbon dioxide to carbon-rich reduction products comprising fuels and other value-added chemicals.

The PIs propose that CO2 reduction to longer carbon chain products is a delicate interplay between chemical potential at the catalytically active transition metal site and intermediate CO (carbon monoxide) adsorption energetics on the catalyst surface. The central hypothesis of this proposal is that high d-electron occupancy with less than a fully filled configuration of the transition metal center along with greater covalency of the metal ligand bond will lead to more selectivity for C2 reduction products at lower applied potential.

Specifically, it is proposed that increasing dwell time of the intermediate CO adsorbed on the catalyst surface will lead to further subsequent reduction of CO to carbon-rich products. The PIs aim to increase dwell time of the CO intermediate on catalyst surface by controlling the d-electron density on the transition metal site that has a direct effect on the metal-to-ligand back bonding which can tune the CO adsorption energy to be within a specific range (between weak and strong adsorption regimes).

This hypothesis will be tested by synthesizing binary, ternary, and quaternary transition metal chalcogenides (selenides and tellurides) comprising Cu, Ni, Fe, Mn, and V, following systematic combinatorial electrodeposition. Experimental studies will be complemented with DFT (Density Functional Theory) calculations where CO and CO2 adsorption kinetics will be estimated on different catalytic surfaces and correlated with their performance.

Specific tasks of this project include: (i) changing the anions across the chalcogenide series and investigating catalytic activity as a function of electronegativity; (ii) aliovalent substitution at the transition metal site which will lead to redistribution of the d-electron cloud increasing redox tunability of the transition metal center as well as facilitate multielectron transfer; (iii) nanostructuring the functional catalysts to increase the active surface area. Major deliverable of this project will be non-precious-metal-based CO2 electroreduction catalysts that can produce higher hydrocarbon-based fuels with lesser expense of electrical energy.

Fundamental insights gained from this comprehensive study have the potential to illuminate design principles used to design more efficient catalysts for carbon capture.

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.