A multi-institutional team led by the US Department of Energy’s (DOE) Argonne National Laboratory (ANL) has developed a low-cost cobalt-based catalyst for the production of hydrogen in a proton exchange membrane water electrolyzer (PEMWE). Other contributors include DOE’s Sandia National Laboratories and Lawrence Berkeley National Laboratory, and Giner Inc..

Proton exchange membrane electrolyzers run with separate catalysts for each of the electrodes (cathode and anode). The cathode catalyst yields hydrogen, while the anode catalyst forms oxygen. The anode catalyst uses iridium, which has a current market price of around $5,000 per ounce. The lack of supply and high cost of iridium pose a major barrier for widespread adoption of PEM electrolyzers.

The main ingredient in the new catalyst is cobalt, which is substantially cheaper than iridium. A paper on their work is published in Science.

We report a nanofibrous cobalt spinel catalyst codoped with lanthanum (La) and manganese (Mn) prepared from a zeolitic imidazolate framework embedded in electrospun polymer fiber. The catalyst demonstrated a low overpotential of 353 millivolts at 10 milliamperes per square centimeter and a low degradation for OER over 360 hours in acidic electrolyte. A PEMWE containing this catalyst at the anode demonstrated a current density of 2000 milliamperes per square centimeter at 2.47 volts (Nafion 115 membrane) or 4000 milliamperes per square centimeter at 3.00 volts (Nafion 212 membrane) and low degradation in an accelerated stress test.

—Chong et al.

We sought to develop a low-cost anode catalyst in a PEM electrolyzer that generates hydrogen at high throughput while consuming minimal energy. By using the cobalt-based catalyst prepared by our method, one could remove the main bottleneck of cost to producing clean hydrogen in an electrolyzer.

—Di-Jia Liu, senior chemist at Argonne and corresponding author

Giner Inc., a leading research and development company working toward commercialization of electrolyzers and fuel cells, evaluated the new catalyst using its PEM electrolyzer test stations under industrial operating conditions. The performance and durability far exceeded that of competitors’ catalysts.

Important to further advancing the catalyst performance is understanding the reaction mechanism at the atomic scale under electrolyzer operating conditions. The team deciphered critical structural changes that occur in the catalyst under operating conditions by using X-ray analyses at the Advanced Photon Source (APS) at Argonne. They also identified key catalyst features using electron microscopy at Sandia Labs and at Argonne’s Center for Nanoscale Materials (CNM). The APS and CNM are both DOE Office of Science user facilities.

In addition, computational modeling at Berkeley Lab revealed important insights into the catalyst’s durability under reaction conditions.

The team’s achievement is a step forward in DOE’s Hydrogen Energy Earthshot initiative, which mimics the US space program’s ​“Moon Shot” of the 1960s. Its ambitious goal is to lower the cost for green hydrogen production to one dollar per kilogram in a decade. Production of green hydrogen at that cost could reshape the nation’s economy. Applications include the electric grid, manufacturing, transportation and residential and commercial heating.

More generally, our results establish a promising path forward in replacing catalysts made from expensive precious metals with elements that are much less expensive and more abundant.

—Di-Jia Liu

This research was supported by the DOE Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office, as well as by Argonne Laboratory Directed Research and Development funding.

Resources

• Lina Chong et al. (2023) “La- and Mn-doped cobalt spinel oxygen evolution catalyst for proton exchange membrane electrolysis” Science 380,609-616 doi: 10.1126/science.ade1499