Nickel Catalysts Get a Boost from Halogen Friends

Nickel catalysts are not as good as their noble metal counterparts for hydrogen oxidation in alkaline environments. They only have 1-2% of their activity. This is a problem because scientists don't fully understand why. But recent research sheds some light on this issue. The study looked at how different anions, like OH - , Br - , Cl - , and SCN - , affect the hydrogen oxidation reaction (HOR) in nickel-based catalysts. The findings were interesting. Br - and Cl - ions stick to the catalyst's surface. This helps speed up hydrogen transfer, making the reaction more efficient. Plus, these ions also block OH - from sticking, which prevents the nickel from oxidizing. This anion adsorption trick improved the HOR activity of the NiMoO x catalyst by 13%. It also delayed the start of nickel oxidation by 40 mV. However, not all anions are helpful. SCN - ions, which are pseudohalogens, are a problem. They stick too tightly to the nickel, poisoning the catalyst and making it less effective. The research showed that using Cl - -modified NiMoO x catalysts in alkaline anion exchange membrane fuel cells can boost peak power density to 234. 3 mW cm -2 . This is 24% higher than unmodified NiMoO x . This study highlights the importance of anion adsorption in improving the performance of nickel-based catalysts. It's a step forward in making these catalysts more viable for practical applications.