Scientists are working towards finding low-cost methods for producing clean hydrogen from water as a replacement for fossil fuels. The hydrogen produced can power vehicles without emitting anything but water and is an important chemical for many industrial processes, including steel making and ammonia production. Using cleaner hydrogen is highly desirable in these industries. A team of researchers led by the U.S. Department of Energy’s Argonne National Laboratory has developed a low-cost catalyst for a process that yields clean hydrogen from water.
The Process of Electrolysis
The process of electrolysis has been around for more than a century and produces hydrogen and oxygen from water. Proton exchange membrane (PEM) electrolyzers represent a new generation of technology for this process. They can split water into hydrogen and oxygen with higher efficiency at near room temperature. The reduced energy demand makes them an ideal choice for producing clean hydrogen using renewable but intermittent sources, such as solar and wind.
Catalyst Development
This electrolyzer runs with separate catalysts for each of its electrodes (cathode and anode). The cathode catalyst yields hydrogen, while the anode catalyst forms oxygen. A problem is that 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.
Giner Inc., a research and development company working towards 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.
Deciphering the Reaction Mechanism at the Atomic Scale
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.
“We imaged the atomic structure on the surface of the new catalyst at various stages of preparation,” said Jianguo Wen, an Argonne materials scientist.
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 aims 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,” said Di-Jia Liu, senior chemist at Argonne.
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