Shaping the energy landscape toward renewable, carbon-free energy resources is a contemporary challenge that will require significant advancements in the development of catalysts/electrocatalysts for energy and chemical conversion processes. The goal of our research group is to design active, selective and stable heterogeneous catalysts and electrocatalysts for these processes. Specifically, we focus on the development of heterogeneous catalysts and electrocatalysts for electrochemical conversion and storage (i.e. fuel cells, electrolyzers, batteries) and cooperative/selective thermal catalysis for biomass upgrading, plastics upcycling and mitigation of greenhouse gasses (i.e., CO2). As an integral part of engineering catalytic/electrocatalytic structures, we implement a paradigm which involves a combination of controlled synthesis, advanced characterization, kinetic measurements and quantum chemical calculations to unearth the underlying mechanism that governs their catalytic performance for targeted reactions.

Research Projects

Engineering nonstoichiometric mixed metal oxides for electrocatalytic and thermal catalytic processes

Nonstoichiometric mixed metal oxides (e.g., perovskites, double perovskites, Ruddlesden−Popper (R-P) oxides, …) are redox and thermally stable materials largely characterized by the oxygen nonstoichiometry in their structure. The latter is a key factor in providing excellent ionic and electronic conductivity to this family of materials, enabling their application as promising heterogeneous catalysts and electrocatalysts for a number of relevant reactions. They are described by a general form of An+1BnO3n+1, where A/B refer to rare earth/alkaline-earth and transition metal cations, respectively. Our research group has focused on engineering the cationic composition and surface structure of these oxides for a number of catalytic and electrocatalytic reactions including electrochemical oxygen reduction and evolution (ORR/OER), dynamic catalysis through external stimuli (i.e., photons), oxidative coupling of methane, CO2 hydrogenation, and NOx reduction. We have shown that nonstoichiometric mixed metal oxides are effective platforms for hosting catalytically active cations and enabling the in-situ generation of highly active catalytic surfaces.

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Related and Selected Publications:

Tuning solid-solid interfacial catalysis in alkali metal-air battery cathodes

The development of high-energy density batteries that enable electrification of the transportation sector remains a challenge. Metal-air batteries, Li/Na-air technologies, have attracted significant interest over the last two decades due to their comparable energy density to that of gasoline. However, these systems are limited by large overpotential losses, during the molecular oxygen electrocatalysis resulting in low voltaic efficiencies. Our approach involves a combination of quantum theoretical calculations, controlled synthesis, kinetic studies, and thorough characterization to study and tune catalysis at the solid-solid interfaces of the battery cathodes where solid discharge products are formed and dissociated on solid electrocatalyst surfaces. The objective is to lower the cell overpotential losses and enhance cell cyclability by tuning the discharge product distribution.

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Diagram of Solution-mediated discharge mechanism

Related and Selected Publications:

H2O splitting and CO2 reduction using solid oxide electrolyzers

The interest in developing solid oxide electrolysis cells (SOECs) for electrochemical reduction of CO2 and water is steadily increasing as an approach to convert surplus energy from intermittent energy sources into chemical energy, while also mitigating CO2 emissions. The key challenges with this technology include high overpotential losses associated with the electrochemical reactions (i.e. oxygen evolution reactions (OER) and CO2 and H2O co-reduction) at the SOEC electrodes. This project aims to (1) investigate the optimization of catalytic activity of SOEC fuel electrode through the use of layered nickelate oxides as promising electrocatalysts for OER, and (2) assess the activity and stability of metal/metal-alloy based electrodes under conventional SOEC working conditions as electrocatalyst for and CO2 and H2O co-reduction. Our approach involves a combination of DFT calculations and microkinetic modeling with controlled electrochemical experiments to understand the chemical/electrochemical processes that govern H2O and CO2 co-electrolysis with the aim of identifying optimal electrocatalysts for this process.

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Graph of different molecule's Normalized rates

Related and Selected Publications:

Design of multifunctional heterogeneous catalysts for selective catalysis

Design of heterogeneous catalysts has experienced significant growth over the last decade especially in relation to sustainable and renewable catalytic processes. Catalytic architectures with multiple dimensionality and functionality at the nanoscale have been developed by our group to tune catalyst activity, selectivity and stability for different catalytic reactions (i.e., CO2 hydrogenation, selective deoxygenation of biomass derived substrates, and plastic upcycling). Some of these include: (i) alloys which modulate the electronic structure of the active metal site along with the two-dimensional environment surrounding that site, and provide multifunctionality through incorporation of a secondary metal, (ii) “inverted” or encapsulated structures characterized by porous metal oxide films deposited on top of metallic substrates used to tune metal-oxide support interactions to exploit interface effects between metals and oxide supports, which have been shown to provide unique active sites exhibiting distinct properties of the two types of materials, while also improving the chemical and thermal stability of metal NPs, and (iii) supported metal NPs modified via surface organic ligands that mimic enzyme like catalytic environments.

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Funding Sources

us department of energy

Department of Energy – Office of Basic Energy Sciences
nsf
National Science Foundation
toyota
Toyota Motor North America, Inc
The Camille and Henry DreyFus Foundation Logo

The Camille & Henry Dreyfus Foundation
Center for Programmable Energy Catalysis Logo
CPEC (Center for Programmable Energy Catalysis)
UNCAGE-ME logo
UNCAGE-ME (Evolution of materials for clean energy technologies)
COMPASS logo
COMPASS (Center for Complex Particle Systems)