CAREER: Experimental Determination and Fundamental Theory of Mesoscopic Transport and Intrinsic Kinetics in CO2 Electrocatalysis

The transformation of carbon dioxide (CO2) to fuels and chemicals using CO2 electrolyzers is a promising path forward for the electrification of the chemical manufacturing industry and the manufacturing of synthetic fuels for energy storage at a global scale. CO2 electrolyzers powered by electrons generated from wind and solar are key enabling technologies to achieve a zero-emissions future.

Among the various metals studied for the electrochemical transformation of CO2, copper is the only single-element metal known to efficiently catalyze the production of multi-carbon oxygenates and hydrocarbons. There is still no consensus on how copper catalyzes this transformation. The rational design of future large-scale CO2 electrolyzers requires information on thermodynamics and reaction-transport kinetics.

This project will address the research need of insufficient information on the reaction-transport kinetics on the copper catalyst system. This project will integrate results from research efforts into the training of undergraduate and graduate students at UCLA while also coordinating outreach activities to community colleges, minority serving institutions, national labs, and industries in California.

The education and broadening impact activities include: i) development of a two year-summer research experience for chemical engineering undergraduate students. ii) outreach to industry and involvement of a diverse group of undergraduate and graduate students in research workshops and collaborations, and iii) introduction of electrochemical engineering concepts, cells, and theories developed in this proposal in the undergraduate chemical engineering capstone course, and the electrochemical processes course taught by the PI.

Recently, it has become evident that transport is on equal footing with intrinsic catalytic kinetics of copper active sites in determining reaction mechanisms and product distributions of CO2 electroreductions, and thus a detailed extraction of reaction kinetics under well-defined mass, heat and charge transport conditions is necessary. This fundamental engineering research project addresses the critical need for the determination and modeling of mesoscopic transport and reaction kinetics relevant to CO2 electrocatalysis by combining: i) reactor design and characterization, ii) accelerated collection, ingestion, and contextualization of large experimental datasets to enable the decoupling of transport contributions from CO2 reduction kinetics, and iii) the development and parametrization of multi-scale reaction-transport models.

The reaction-transport model developed here will be the first of its kind for electrochemical CO2 reduction and should enable the future rational design and scale-up of CO2 electrolyzers. The research will explore how mass, heat and charge transport determine product selectivity in CO2 reduction and will develop the fundamental theory and tools needed to build a reaction-transport model of electrocatalytic processes on copper electrodes.

Electrochemical cells with well-defined transport properties will be utilized as tools to generate large experimental datasets of correlations between six experimental variables (applied potential, transport characteristics in the cell, electrolyte composition, temperature, pressure and catalyst porosity) and the production rates for 16 different liquid and gas products on copper catalysts. This large dataset will be of high quality and will be used to determine the underlying CO2 reduction mechanism on copper electrodes and the contribution of external and internal mass, heat and charge transport effects on the generation of different product distributions observed on catalysts with different porosities.

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.