Ryan Hannagan

All Publications

• On-line Inductively Coupled Plasma Mass Spectrometry Reveals Material Degradation Dynamics of Au and Cu Catalysts during Electrochemical CO2 Reduction. Journal of the American Chemical Society Yan, K., Lee, S. W., Yap, K. M., Mule, A. S., Hannagan, R. T., Matthews, J. E., Kamat, G. A., Lee, D. U., Stevens, M. B., Nielander, A. C., Jaramillo, T. F. 2025

  Abstract

  A significant challenge in commercializing electrochemical CO2 reduction (CO2R) is achieving catalyst durability. In this study, online inductively coupled mass spectrometry (ICP-MS) was used to investigate catalyst degradation via nanoparticle detachment and/or dissolution into metal ions under CO2R operating conditions in 0.1 M KHCO3. We developed an experimental framework with ex situ characterization to validate the online ICP-MS method for in situ evaluation of degradation from metal foils. By varying the applied potential and microenvironment (CO2 vs N2-saturated electrolyte), we gained insights into the degradation of Au and Cu foils under CO2R and hydrogen evolution reaction (HER) conditions. While both Au and Cu foils were observed to be stable to dissolution in these regimes, degradation via nanoparticle detachment from the foil surface at the femtogram scale was observed as a function of reaction conditions, providing new insights into material degradation mechanisms. When applying potential steps at -0.1 and -1.0 V vs the reversible hydrogen electrode (RHE), Au was found to degrade via nanoparticle detachment under CO2R operating conditions more than under HER conditions, while Cu was found to degrade via nanoparticle detachment in similar amounts during both reactions. Au lost ∼1.8× more mass and ∼7.5× more nanoparticles than Cu under CO2R operating conditions. This study demonstrates the use of online ICP-MS to gain insight into the degradation of Au and Cu, the importance of studying unconventional degradation mechanisms such as nanoparticle detachment, and that online ICP-MS can be further utilized to gain fundamental understanding of catalyst durability for a variety of reaction systems.

  View details for DOI 10.1021/jacs.4c13233

  View details for PubMedID 39871661

• Understanding the Effects of Anode Catalyst Conductivity and Loading on Catalyst Layer Utilization and Performance for Anion Exchange Membrane Water Electrolysis. ACS catalysis Kreider, M. E., Yu, H., Osmieri, L., Parimuha, M. R., Reeves, K. S., Marin, D. H., Hannagan, R. T., Volk, E. K., Jaramillo, T. F., Young, J. L., Zelenay, P., Alia, S. M. 2024; 14 (14): 10806-10819

  Abstract

  Anion exchange membrane water electrolysis (AEMWE) is a promising technology to produce hydrogen from low-cost, renewable power sources. Recently, the efficiency and durability of AEMWE have improved significantly due to advances in the anion exchange polymers and catalysts. To achieve performances and lifetimes competitive with proton exchange membrane or liquid alkaline electrolyzers, however, improvements in the integration of materials into the membrane electrode assembly (MEA) are needed. In particular, the integration of the oxygen evolution reaction (OER) catalyst, ionomer, and transport layer in the anode catalyst layer has significant impacts on catalyst utilization and voltage losses due to the transport of gases, hydroxide ions, and electrons within the anode. This study investigates the effects of the properties of the OER catalyst and the catalyst layer morphology on performance. Using cross-sectional electron microscopy and in-plane conductivity measurements for four PGM-free catalysts, we determine the catalyst layer thickness, uniformity, and electronic conductivity and further use a transmission line model to relate these properties to the catalyst layer resistance and utilization. We find that increased loading is beneficial for catalysts with high electronic conductivity and uniform catalyst layers, resulting in up to 55% increase in current density at 2 V due to decreased kinetic and catalyst layer resistance losses, while for catalysts with lower conductivity and/or less uniform catalyst layers, there is minimal impact. This work provides important insights into the role of catalyst layer properties beyond intrinsic catalyst activity in AEMWE performance.

  View details for DOI 10.1021/acscatal.4c02932

  View details for PubMedID 39050897

  View details for PubMedCentralID PMC11264204

• Understanding the Effects of Anode Catalyst Conductivity and Loading on Catalyst Layer Utilization and Performance for Anion Exchange Membrane Water Electrolysis ACS CATALYSIS Kreider, M. E., Yu, H., Osmieri, L., Parimuha, M. R., Reeves, K. S., Marin, D. H., Hannagan, R. T., Volk, E. K., Jaramillo, T. F., Young, J. L., Zelenay, P., Alia, S. M. 2024

  View details for DOI 10.1021/acscatal.4c02932

  View details for Web of Science ID 001265524300001

• Protocol for assembling and operating bipolar membrane water electrolyzers. STAR protocols Rios Amador, I., Hannagan, R. T., Marin, D. H., Perryman, J. T., Rémy, C., Hubert, M. A., Lindquist, G. A., Chen, L., Stevens, M. B., Boettcher, S. W., Nielander, A. C., Jaramillo, T. F. 2023; 4 (4): 102606

  Abstract

  Renewable energy-driven bipolar membrane water electrolyzers (BPMWEs) are a promising technology for sustainable production of hydrogen from seawater and other impure water sources. Here, we present a protocol for assembling BPMWEs and operating them in a range of water feedstocks, including ultra-pure deionized water and seawater. We describe steps for membrane electrode assembly preparation, electrolyzer assembly, and electrochemical evaluation. For complete details on the use and execution of this protocol, please refer to Marin et al. (2023).1.

  View details for DOI 10.1016/j.xpro.2023.102606

  View details for PubMedID 37924520