The advantage of PEFCs is their high efficiency in converting fuel to electricity with low emissions and at low operating temperatures. The fuel of choice for many PEFC power applications is hydrogen due to its high energy density per mass of fuel, high conversion efficiency and non-carbon-containing emissions. Three major issues impeding the widespread implementation of PEFC power systems based around hydrogen for portable power and transportation use are hydrogen fuel cost, hydrogen fueling infrastructure, hydrogen fuel storage, and PEFC system cost and lifetime. The Hydrogen and Fuel Cell Materials group in CSE has active research projects to develop new materials and enable existing materials to overcome the major barriers to enable cost-competitive use of this promising technology in a variety of applications.
This work if primarily funded by the Hydrogen and Fuel Cell Technologies Office (HFTO) in the Department of Energy’s (DOE) Office of Energy Efficiency and Renewable Energy. The focus of HFTO has historically been on the automotive application, where cost competitiveness with the incumbent internal combustion engine requires PEFCs with low loadings of costly platinum-based electrocatalyst. Recently, HFTO’s R&D emphasis has shifted to PEFC systems for heavy duty vehicles, such as long-haul trucks, and has established two new consortia to address hydrogen production and PEFC performance and durability for these applications. The emphasis here is on efficiency (i.e., performance at high voltages) and durability and less on cost.
In support of its H2@Scale initiative, HFTO is also exploring processes to convert hydrogen into liquid fuels or chemicals. One such process converts captured carbon dioxide to fuels such as methanol and ethanol using electrochemical reduction. Electrochemical processes can serve as effective means to store and utilize the energy produced from intermittent, renewable sources such as solar and wind.
Our research addresses the main issues facing the widespread deployment of PEFC power systems for numerous applications: performance, durability and cost. The group’s research also addresses the use of fuel cells for transportation applications: lack of cost-effective hydrogen and suitable high-capacity hydrogen storage materials. Additionally, the group is also developing materials and supporting the development of cells for the electrochemical conversion of carbon dioxide to fuels.
PGM Free Catalysts
A major cost contributor to PEFC power systems and one of the major sources of efficiency loss is the platinum-based catalyst. To address this issue, the Hydrogen and Fuel Cell Materials group is developing platinum group metal-free (PGM-free) catalysts with the aim of maximizing the active site density, accessibility of the active sites, and the activity and durability of those sites. To achieve these goals, the group is utilizing high-throughput materials synthesis coupled with machine learning,1 characterization2 and equipment and methodologies development for performance evaluation.3 This research takes advantage of the capabilities within CSE’s high-throughput research laboratory. This activity is a cornerstone of the DOE’s ElectroCat research consortium, which is co-led by Argonne and Los Alamos National Laboratory.
Platinum Alloy Electrocatalysts
Another of the group’s research areas focuses on developing novel platinum and platinum alloy catalysts and on achieving high performance from advanced platinum alloy electrocatalysts by tuning the electrode layer composition and structure. One such novel catalyst approach utilizes a PGM-free catalyst as a support for platinum alloy nanoparticles.4 The group also seeks to determine the performance-limiting properties of the platinum alloy catalysts, electrode layer precursor solutions, and electrodes utilizing a combination of in-cell diagnostics and structural analyses and X-ray scattering, spectroscopy, and tomography techniques at Argonne’s Advanced Photon Source.5,6 The information from these characterizations and the impact of electrode layer composition and precursor solution solvent on the performance and structure is used to inform the design of electrodes with technology-enabling performance (FC-PAD, the Fuel Cell Consortium for Performance and Durability).
Our group is addressing the limited durability of PEFCs by identifying the mechanisms of catalyst degradation and determining the catalyst, catalyst support properties and operating conditions that limit catalyst lifetime. This research utilizes ex situ, in situ, and in operando X-ray absorption and scattering techniques at Argonne’s Advanced Photon Source, aqueous dissolution studies, modeling of platinum dissolution and de-alloying, and modeling of the effect of catalyst degradation on cell performance, in collaboration with Argonne’s Energy Systems Division.7,8
Water electrolysis to form hydrogen represents one of the critical technologies for distributed hydrogen production. Electrolysis produces clean hydrogen with fast response time. A barrier to widespread implementation of this hydrogen production technology is cost and durability. Due to the sluggish kinetics of the oxygen evolution reaction (OER), high loadings of costly iridium are needed to achieve reasonable electrolyzer efficiency and durability. The group is developing PGM-free OER catalysts to address the cost and durability issues of iridium OER catalysts. These materials are based on porous, stable transition metal composites derived from, for example, cobalt metal organic frameworks incorporated into a 3-D nano-network architecture.9
Although hydrogen is the fuel of choice for these applications, it has a low energy density per unit volume. As such, storage as a compressed gas is limited in capacity, and compression is also energy intensive. Therefore, the group is working to develop lightweight and compact materials that can store large amounts of hydrogen at ambient temperatures, release hydrogen quickly at PEFC temperatures, and recharge quickly and easily. Two classes of hydrogen storage materials we have developed are chemical hydrides, such as graphene-wrapped borohydrides (HyMARC: Hydrogen Materials Advanced Research Consortium),10 and highly-porous adsorbents with high surface area, such as porous organic polymer and metal organic frameworks.11
Carbon Dioxide to Fuel
Our group, in collaboration with Northern Illinois University, is developing highly effective and selective copper-based catalysts for the direct electrochemical conversion of carbon dioxide to ethanol.12 In collaboration with the National Renewable Energy Laboratory, the group is providing critical information for the development of selective, high efficiency, high current density cells for the conversion of carbon dioxide to fuels, such as formaldehyde.13
- M. Karim, M. Ferrandon, S. Medina, E. Sture, N. Kariuki, D.J. Myers, E.F. Holby, P. Zelenay, and T. Ahmed, ACS Applied Energy Materials, doi:10.1021/acsaem.0c01466 (2020).
- Luigi Osmieri, Rajesh K. Ahluwalia, Xiaohua Wang, Hoon T. Chung, Xi Yin, A. Jeremy Kropf, Jaehyung Park, David A. Cullen, Karren L. More, Piotr Zelenay, Deborah J. Myers, and K.C. Neyerlin, Applied Catalysis B: Environmental, 257 (2019) 117929.
- Jaehyung Park and Deborah J. Myers, Journal of Power Sources, 480 (2020) 228801-228810.
- L. Chong, J. Wen, J. Kubal, F. Sen, J. Zou, J. Greeley, M. Chan, H. Barkholtz, W. Ding, D.-J. Liu, Science, 362 (2018) 1276-1281.
- Min Wang, Jae Hyung Park, Sadia Kabir, K.C. Neyerlin, Nancy N. Kariuki, Haifeng Lv, Vojislav R. Stamenkovic, Deborah J. Myers, Michael Ulsh, and Scott Mauger, ACS Applied Energy Materials, 2 (2019) 6417-6427.
- Firat C. Cetinbas, Rajesh K. Ahluwalia, Nancy N. Kariuki, Vincent De Andrade, and Deborah J. Myers, Journal of the Electrochemical Society, 167 (2020) 013508-013516.
- Deborah J. Myers, Xiaoping Wang, Matt C. Smith, and Karren L. More, Journal of the Electrochemical Society, 165(6) (2018) F3178-F3190.
- Rajesh K. Ahluwalia, Dionissios D. Papadias, Nancy N. Kariuki, Jui-Kun Peng, Xiaoping Wang, Yifen Tsai, Donald G. Graczyk, and Deborah J. Myers, Journal of the Electrochemical Society, 165(6) (2018) F3024-F3035.
- Di-Jia Liu, Gang Wu, and Hui Xu, “PGM-free OER Catalysts for PEM Electrolyzer,” 2020 DOE Hydrogen and Fuel Cells Program Annual Merit Review and Peer Evaluation Meeting, https://www.hydrogen.energy.gov/pdfs/review20/p157_liu_2020_p.pdf.
- L. Chong, X. Zeng, W. Ding, D.-J. Liu, and J. Zou, Advanced Materials, 27 (2015) 5070–5074.
- Shengwen Yuan, Brian Dorney, Desiree White, Scott Kirklin, Peter Zapol, Luping Yu, and Di-Jia Liu, Chemical Communications, 46 (2010) 4547-4549.
- Haiping Xu, Dominic Rebollar, Haiying He, Lina Chong, Yuzi Liu, Cong Liu, Cheng-Jun Sun, Tao Li, John V. Muntean, Randall E. Winans, Di-Jia Liu, and Tao Xu, Nature Energy, https://doi.org/10.1038/s41560-020-0666-x (2020).
- Yingying Chen, Ashlee Vise, Ellis Klein, Firat C. Cetinbas, Deborah J. Myers, Wilson A. Smith, Todd G. Deutsch, and K.C. Neyerlin, ACS Energy Letters, 5 (2020) 1825-1833.