Platinum has been the main catalyst for hydrogen-producing reactions, but it has a low affinity for water molecules. This results in a slow rate of water electrolysis. Attempts have been made to combine metal-sulfide with platinum nanoparticles that promote water electrolysis, but the unstable nature of platinum/metallic-sulfide surfaces reduces the durability of catalysts.
To overcome those limitations, a research team — led by professor In Su Lee and Soumen Dutta of the Dept. of Chemistry, Pohang University of Science and Technology (Pohang, South Korea; www.postech.ac.kr) — has designed a “sandwich” catalyst consisting of a platinum/metal-hydroxide interface. The team grew a 1-nm platinum layer on the surface of nickel/iron-double-hydroxide, thus synthesizing 2D-2D nanohybrid materials in the form of sandwiches containing 2D-nickel/iron-hydroxide-nano plates.
This synthesized sandwich catalyst has shown more than six times the activity of the conventional catalytic material (20%-Pt/C), and is said to maintain stable catalytic action in the H2-producing reaction of water electrolysis for more than 50 hours. “Sandwich catalysts have the highest alkali solution hydrogen-producing catalytic activity among substances that do not use carbon supports, but are significantly more durable than similar electrochemical catalysts that are stable for just three to five hours,” says Lee.