Fuel cells are devices that produce electricity by converting chemical energy directly into electrical energy.
Unlike batteries, which store electricity and eventually run out, fuel cells can keep generating power as long as they receive a supply of fuel and oxygen from the air.
Because of this ability, many researchers see fuel cells as an important technology for clean energy in the future.
Different types of fuels can be used in fuel cells, including hydrogen, natural gas, and other energy sources.
However, the chemical reactions that release electricity inside these systems are very complex and not fully understood.
These knowledge gaps make it harder to design fuel cells that can work reliably with a wide range of fuels.
One major problem affects a type called solid oxide fuel cells, often abbreviated as SOFCs.
These fuel cells operate at high temperatures and are considered promising for generating clean electricity from fuels such as natural gas, biogas, or synthetic gas.
But they are highly sensitive to sulfur contamination.
Even very small amounts of sulfur, especially in the form of hydrogen sulfide, can quickly damage the fuel cell. This problem is known as “sulfur poisoning.”
When sulfur reaches the fuel cell’s anode—the electrode where fuel reactions occur—it forms chemical compounds that stick to the surface and block important reaction sites. As a result, the fuel cell loses efficiency and produces less electricity.
Researchers at the University of Utah have now discovered a promising way to overcome this problem. In a new study published in the Journal of the American Chemical Society, the team found that adding a small amount of the metal rhodium to the fuel cell’s nickel-based anode can help the system clean itself during operation.
The research team was led by chemical engineering professor Chuancheng Duan, with graduate student Yue Bao serving as the study’s lead author. Their work shows that rhodium helps form extremely small particles made of both nickel and rhodium on the surface of the anode. These particles behave differently from ordinary nickel surfaces.
In traditional fuel cells, sulfur binds tightly to nickel atoms, creating stable nickel-sulfur compounds that block the surface. But when rhodium is present, this bonding becomes weaker. At the same time, rhodium helps activate water molecules in the fuel cell’s environment. These water molecules produce highly reactive hydroxyl species.
These reactive molecules then interact with the sulfur attached to the surface and convert it into sulfur dioxide, a gas that can easily escape from the fuel cell. In other words, the catalyst essentially removes the sulfur contamination on its own.
Because of this process, the fuel cell becomes much more resistant to sulfur poisoning. In experiments, fuel cells using the new nickel-rhodium catalyst produced more than three times the power of traditional designs when operating with fuel containing small amounts of sulfur contamination.
Another advantage is that the catalyst can regenerate itself during normal operation when steam is present. This means the fuel cell can maintain performance without requiring complicated cleaning procedures or special sulfur-removal equipment.
The researchers say this discovery could help make fuel cells more practical for real-world energy systems, especially those that rely on fuels like natural gas or biogas, which often contain trace amounts of sulfur.
Beyond fuel cells, the findings may also improve other high-temperature chemical technologies and energy systems that face similar contamination challenges.
The study shows that carefully designing catalyst materials could allow future energy devices not only to tolerate impurities but to actively clean themselves while running.
