New Catalyst Enables Cheaper Production of Hydrogen Fuel

Imagine a world where cars run on fuel derived from water instead of gasoline. Scientists at the University of Texas at Austin and elsewhere are developing methods for splitting water into hydrogen and oxygen that could someday power hydrogen fuel cells. One key challenge has been the high cost of catalysts, chemicals that shepherd the electrolytic reaction.

Now a team of researchers from UT Austin, Massachusetts Institute of Technology and Skoltech Institute of Science and Technology in Russia report the discovery of a new catalyst that significantly improves the efficiency of water electrolysis under alkaline conditions. Their results were recently published in the journal Nature Communications.

Currently, there are a number of challenges for widespread adoption of water electrolyzers to create hydrogen fuel, including high cost, high energy consumption and limited durability. For example, the use of expensive precious metals like platinum and iridium limits implementation at large scale.

"If we could develop catalysts made with Earth abundant materials that could reversibly and efficiently electrolyze water into hydrogen and oxygen, we could have affordable hydrogen generation from renewables; and with that the possibility of cars that run on water with ranges similar to gas powered cars," said UT Austin chemistry graduate student and lead author of the study Tyler Mefford. "To develop these catalysts, we need to understand at the atomic level how these processes proceed and what factors of the catalysts influence their performance."

The team was co-led by Keith Stevenson, adjunct professor in the Department of Chemistry and Keith Johnston, professor in the Department of Chemical Engineering.

To overcome the limitations of current materials, the team synthesized a series of catalysts where the properties of the materials could be controllably modified by the substitution of the element strontium into the chemical structure. The team developed the catalyst strontium cobalt oxide (SrCoO_2.7), which can perform the water electrolysis reaction approximately twenty times better than the leading industrial catalyst iridium oxide (IrO₂) at a significantly lower cost.

The key to this enhanced performance is that oxygen atoms inside the surface of the crystal participate in the reaction. Previously, the assumption had been that the reaction proceeded through chemical species exclusively at the interface between the catalyst and water.

Although more work needs to be done to further increase the performance of water electrolysis catalysts, the work provides a deeper mechanistic understanding of the chemistry of active catalysts. The work also clarifies materials design strategies to accelerate the discovery of additional Earth abundant non-precious metal oxide catalysts.