Self-cleaning electrode makes fuel cell use gas

Using cerium oxide nanoparticles, researchers at the Georgia Institute of Technology have developed a self-cleaning technology that allows solid oxide fuel cells to use gas directly as a fuel at a temperature of 750°C. This technology can provide a more clean and effective alternative to traditional power plants. Related research results were published at Nature Communications.

Traditional coal-fired power plants can only use one-third of the fuel's own energy, and fuel cells can use about 50%. If gas turbines and fuel cells can form a hybrid system, researchers believe that the energy utilization rate can be increased to 80%, reducing the amount of coal needed to provide the same amount of energy and thus reducing carbon dioxide emissions. However, so far, carbon-containing fuels, such as gas or propane, have blocked the electrodes by the carbon deposits produced by the coking process and quickly deactivated the anode of the fuel cell, especially at low temperatures.

To solve this problem, a research team led by the Georgia Institute of Technology used a vapor deposition process to attach cerium oxide nanoparticles to the fuel cell anode. These particles are between 10 and 100 nanometers in diameter and form an "island" on the nickel surface without blocking electrons from passing through the electrode surface. When the water vapor in the gas comes into contact with the cerium oxide, it is absorbed and decomposed into H+ and OH- ions. The OH- ions move toward the nickel surface where they combine with the deposited carbon atoms to become an intermediate and then decompose into CO and H2, which both provide energy to the fuel cell and form CO2 and water. Half of CO2 returns to coal gasification. With this method, the surface of the nickel electrode can be kept clean.

The researchers also evaluated the use of propane as a fuel cell fuel using a new electrode system. Like the gas system, the propane system operated successfully for a while.

Researchers have been testing the new process for hundreds of hours, and no carbon deposition has been found. The formation of the yttria structure can be part of a conventional electrode assembly process and does not require additional steps. One of the major challenges in the current study is to test the durability of the system to accommodate fuel cell systems with a design life of five years.