New Catalyst for Hydrogen Production

Mineral pentlandite works just as efficient as expensive platinum electrodes commonly used today. In contrast to platinum, pentlandite is affordable and found frequently on Earth. In addition to platinum, there are numerous other substances that can catalyse the reaction of water to hydrogen and oxygen and do not contain any precious metals. Among such compounds are the so-called metal chalcogenides. Usually, however, these non-metallic materials are distinctly poorer conductors of electrons and are thus inefficient catalysts.

Pentlandite consists of iron, nickel, and sulfur. Its structure is similar to the active center of hydrogenases, which are hydrogen-producing enzymes, as found, for example, in green algae. In the current study, the researchers compared the hydrogen production rate of naturally obtained and artificially produced pentlandite with platinum and other non-metallic catalysts.

Artificial pentlandite and platinum prove to be equally good catalysts, with a performance that surpasses that of all the other materials tested. The mineral synthesized in the lab produced hydrogen much more efficiently than the naturally found variant. The reason: Inclusions of magnesium and silicon in natural pentlandite reduce its conductivity. The scientists called the output of artificial pentlandite “surprisingly high,” and the rate of synthesis also remained stable for a long time.

The mineral has another advantage compared to other non-precious-metal materials. It has a greater active surface area to which the reacting substances can dock. In other non-precious-metal materials, this surface has to be created using complex methods by applying the catalyst to an electrode in the form of nanoparticles.

http://aktuell.ruhr-uni-bochum.de/pm2016/pm00108.html.en

http://www.nature.com/ncomms/2016/160727/ncomms12269/full/ncomms12269.html