A research team led by UCLA materials scientists and chemists has designed a new catalyst that could make fuel cells more durable, nearly doubling the projected lifetime target set by the U.S. Department of Energy.

The advance involving embedding cobalt oxide clusters in an ultrafine platinum catalyst has resulted in much more durable fuel cells, which have been considered the most efficient means to generate electricity with limited carbon footprint.

A study outlining the findings was published recently in Nature Catalysis. Led by UCLA Samueli School of Engineering materials science and engineering professor Yu Huang, the researchers estimate that light-duty vehicles, such as passenger cars, equipped with the new durable fuel cells could last beyond 15,000 hours of use — 87.5% longer than the energy department’s ultimate goal of 8,000 hours, or roughly 150,000 miles. The improved longevity could also benefit heavy-duty vehicles, such as long-haul semi-trucks, by slightly increasing the use of the embedded-oxide platinum catalyst.

Proton-exchange membrane fuel cells that directly convert the chemical energy in hydrogen to electricity have been an attractive zero-emission power-generation technology. Inside the cells, the membrane is laced with a catalyst, such as a platinum alloy, which helps spark and speed up the otherwise sluggish chemical reaction that converts the energy stored in hydrogen atoms to electricity. The reaction breaks hydrogen atoms into their constituent protons and electrons, with water vapor being the reaction’s only emission byproduct. This is why adopting fuel-cell vehicles for widespread use offers an attractive option for meeting climate sustainability goals.

However, it has been difficult to find the sweet spot between achieving catalytic efficiency and fuel cell durability because the platinum dissolves over time, dropping the fuel cell’s performance.

“A major challenge in wider fuel cell adoption continues to be making their optimal performance last long enough to be commercially viable,” said Huang, who holds the Traugott and Dorothea Frederking Endowed Chair at UCLA Samueli. “Our research demonstrated an atomic interior scaffold that holds platinum atoms in place in the catalyst so they remain stable over an extended period of time.”

Rather than using a traditional platinum alloy, the researchers embedded clusters of cobalt-oxide molecules inside shells of platinum atoms. The design leverages the strong platinum-oxide interaction, which makes the catalyst more durable structurally and chemically without sacrificing fuel cell activity. The resulting hybrid structure helps the platinum ions stick and stay together despite extended use, reducing catalyst-replacement costs. In their experiments, the researchers saw this design outperformed traditional platinum-cobalt alloys in durability and longevity. The team also verified the nanoscale structure using a suite of microscopic, spectroscopic and simulation techniques.

Lead authors on the study are UCLA Ph.D. graduates Bosi Peng and Zeyan Liu of the Huang Research Group, which specializes in developing nanoscale building blocks for complex materials, including fuel cell catalysts.

Joining Huang as a senior co-corresponding author is Alessandro Fortunelli of the National Research Council in Italy. UCLA chemistry and biochemistry professor Xiangfeng Duan and UC Irvine materials science and engineering professor Xiaoqing Pan are also authors of the study, which was funded in part by the U.S. Office of Naval Research.

Duan and Huang are members of the California NanoSystems Institute at UCLA. The UCLA Technology Development Group has filed for a provisional U.S. patent on the technology.

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