Princeton University discovers platinum alternative that could lead to cheaper fuel cells

(Image source: Princeton University official website)

As we all know, platinum is expensive and is one of the serious obstacles to the large-scale application of hydrogen fuel cells, one of the energy sources for electric vehicles , because hydrogen fuel cells require platinum. However, according to foreign media reports, a research team led by Bruce E. Koel, a professor of biological and chemical engineering at Princeton University, successfully found a cheaper alternative to platinum. The researchers said that they found a hafnium-based compound that is about 60% as efficient as platinum, but the cost is only about one-fifth of platinum.

Fuel cells work by converting the energy stored in hydrogen atoms directly into electricity. NASA has long used fuel cells to power satellites and other space missions, and now they are also being used in electric cars and buses. Hydrogen is the simplest and most abundant element on the planet and in the universe.

At its most basic, fuel cells generate electricity by splitting hydrogen into protons and electrons. The protons flow through a membrane to combine with oxygen to form water, and the negatively charged electrons flow to the positively charged electrodes in the fuel cell. The flow of electrons is the current generated by the fuel cell, which can power a motor or other electronic device, but the splitting process requires materials such as platinum as catalysts.

Catalysts are also used in hydrogen-fueled fuel cells to produce hydrogen. In the best-case scenario, renewable electricity can be used with the help of catalysts to split water molecules (two hydrogen atoms and one oxygen atom) into oxygen and hydrogen, and the more efficient the catalyst, the less energy is required to split the water.

Some advanced fuel cells, called renewable fuel cells, combine both reactions. However, most current fuel cells rely on hydrogen produced by a separate system to become a hydrogen fuel cell. However, the best catalysts for both reactions are currently platinum group precious metals. Researchers believe platinum is perfect because platinum group precious metals can quickly and efficiently catalyze the chemical reactions to extract hydrogen, and these metals can withstand the harsh acidic conditions required for these reactions.

The problem is that platinum is both rare and expensive, but researchers feel that hydrogen fuel cells for electric vehicles and the like do not need platinum as a perfect material. The researchers found that hafnium hydroxide is a good substitute, and nitrogen atoms can be drawn into the material by treating it with nitrogen plasma (plasma is an ionized gas, a state of matter found in fluorescent lamps and the sun).

Previously, many materials were overlooked because they do not conduct electricity. However, the researchers found that treating hafnium oxide with nitrogen plasma formed a thin film of material that can act as a highly active catalyst that can survive strong acid conditions. Although the hafnium-based film is only about two-thirds as efficient as platinum, it is much cheaper. The researchers plan to test zirconium next because it is even cheaper.

While the material is well suited for use in fuel cells, the researchers believe it would be most valuable in systems that use catalysts to electrochemically split water to produce hydrogen as a fuel. The researchers also stressed that their discovery would not enable new, inexpensive technologies to be commercialized in the near future. Currently, the process of making the material is complex and limited to the laboratory. While they have determined the properties of the film, they still need to consider the engineering technology required to mass-produce the material. However, the research opens the door to further exploration of alternative materials to platinum.