The project will employ an integrated theoretical and experimental approach to rapidly discover highly efficient catalysts, based on two-dimensional (2D) materials in contact with an ionic liquid, for a variety of electrochemical reactions of importance for sustainable energy generation, chemicals manufacturing, environmental remediation, and energy storage. Electrocatalysis - as employed in energy storage and conversion devices such as advanced batteries, fuel cells, photovoltaics, and chemical electrolyzers - is becoming an increasingly important alternative to conventional thermal catalysis, but needs further improvements in efficiency, cost reduction, and chemical selectivity for wide-scale commercial implementation. The project will address those needs by combining first-principles density functional theory calculations, including solvent interaction effects and theory-guided machine learning, to identify new ionic-liquid electrolytes and low-cost 2D materials capable of displacing existing thermal processes with electrocatalytic processes utilizing renewable and/or sustainable resources. Educational and outreach components of the project will focus on preparing both graduate and undergraduate students for the workforce needed to realize advanced energy technologies. Emphasis at both universities will be placed on the recruitment of minority and underrepresented student populations through existing programs including the Minority Engineering Recruitment and Retention Program (MERRP) at the University of Illinois-Chicago, and the Office of Undergraduate Research at Washington University. The theoretical and experimental dataset on 2D materials generated in the study, along with relevant computational codes, will be disseminated to the broader research community through on-line repositories.
Two-dimensional transition metal dichalcogenides (TMDCs) in contact with ionic liquid (IL) electrolytes will be used as the starting materials offering a new paradigm for electrocatalysis based on materials with low work function, significant overlap of the d-band partial density of states with the Fermi energy, and an electrolyte 'solvent' that protects rather than poisons the catalytic sites. Novel material combinations and structures will be predicted using computational tools and then synthesized using chemical vapor deposition, chemical vapor transport and colloidal chemistry. Atomic and electronic structure will be characterized using in-situ aberration-corrected scanning transmission electron microscopy (STEM). The information obtained from high-resolution STEM, including high-angle annular dark-field (HAADF) and annular bright-field (ABF) imaging, as well as electron energy loss spectroscopy (EELS) and energy dispersive X-ray spectroscopy (XEDS), will be used to confirm successful synthesis of the desired structures and to create starting configurations for the first-principles modeling efforts. Both ex-situ and in-situ electrochemical experiments will be conducted to measure the activity and selectivity of the synthesized materials. In particular, the study will utilize a novel graphene liquid cell, developed by one of the investigators, that enables atomic-resolution imaging and spectroscopy in a liquid environment. Mechanistic studies of the electrocatalytic reactions and transport measurements will be made utilizing in-situ differential electrochemical mass spectrometry (DEMS) together with a traditional silicon nitride based electrochemical stage for STEM characterization under operando conditions. Taken together, the advanced synthesis, characterization, and evaluation techniques, coupled with efficient computational search methods, will accelerate the discovery of 2D material-based-catalysts with superior activity and selectivity for various electrochemical reactions including the oxygen reduction reaction (important in fuel cell technology), and the hydrogen evolution reaction (important in water electrolysis).
