Modeling CO2 Reduction Electrolyzers
The electrochemical reduction of CO2 (CO2R) to value-added products is an attractive technology for tackling the rising atmospheric CO2 levels and storing intermittent renewable energy. Our group is interested in understanding the complex interplay between species transport, unfavorable CO2/OH- interactions, and electrochemical reaction kinetics in CO2R systems. Using multiphysics modeling, we can study the performance and limitations of various cell design architectures, and guide the design of next-generation CO2R devices.
Figure at right: Modelling results for two membrane-electrode assembly (MEA) configurations with a Ag cathode performing CO2R to CO. The KHCO3 and KOH exchange-MEAs can achieve higher current densities than the full-MEA due to better membrane hydration, but is limited to ca. 700 mA cm-2 by salt precipitation at the cathode. Circulating liquid H2O at the anode (H2O-MEA) can improve membrane hydration and circumvent salt-precipitation issues seen in exchange-MEAs.
Weng, Lien-Chun, Alexis T Bell, and Adam Z Weber. "Towards membrane-electrode assembly systems for CO 2 reduction: a modeling study." Energy & Environmental Science 12.6 (2019) 1950 - 1968
Solar Water-Splitting Devices
Solar water-splitting is a promising approach to convert and store solar energy in the form of stable chemical bonds. For solar-hydrogen production, particle-suspension reactor designs comprising suspended photocatalysts in an aqueous electrolyte are projected to be cost-efficient alternatives to the more exhaustively optimized fixed-electrode device architectures. We use multiphysics modeling to study device-scale transport, kinetic, and optical processes, and their impacts on the solar-to-hydrogen efficiencies for these designs.
Figure at right: (a) Schematic of the vertically stacked particle-suspension reactor design which affords tandem light absorption for Z-scheme solar water splitting, and (b) the desired chemistry and direction of electron transfer reactions on the surface of the semiconductor particles, assuming acidic conditions.
Chandran, Rohini Bala, Sasuke Breen, Yuanxun Shao, Shane Ardo, and Adam Z Weber. "Evaluating particle-suspension reactor designs for Z-scheme solar water splitting via transport and kinetic modeling." Energy & Environmental Science 11.1 (2018) 115 - 135.