Scientists have developed a new type of catalyst that is far better at splitting water into hydrogen and oxygen than previous methods. In fact, the new catalyst is three times better than the previous record holder.
"The good things about this catalyst are that it's easy to make, its production can be very easily scaled up without any super-advanced tools, it's consistent, and it's very robust," said Aleksandra Vojvodic, a SLAC staff scientist.
Scientists have long been searching for an efficient way to store electricity generated by solar and wind power so that it can be used any time - not just when the sun shines and the wind blows. One way in order to accomplish this is by using an electrical current to split water molecules into hydrogen and oxygen. Then, the hydrogen is stored to later use as fuel.
However, this reaction isn't always efficient. It takes place in several steps, and each of these steps requires a catalyst to move it along. In this case, though, the researchers focused on a step where oxygen atoms pair up to form a gas that bubbles away, which has long been a bottleneck in the process.
In this latest study, the researchers added tungsten to an iron-cobalt catalyst; this worked, but not very efficiently. The researchers then used computers and found that adding tungsten should dramatically increase the catalyst's activity. This would largely be true if the three metals could be mixed so that their atoms were uniformly distributed.
Based on this information, the researchers created a new way to distribute the three metals; they dissolved the metals in a solution and then slowly turned the solution into a gel at room temperature. This gel was then dried to a white particle whose particles were riddle with pores to increase the surface area where chemicals could attach and react with each other.
In this case, the researchers found that the catalyst was three times faster, per unit weight, than the previous record holder.
"It's a big advance, although there's still more room to improve," said Edward H. Sargent, a professor at the University of Toronto. "And we will need to make catalysts and electrolysis systems even more efficient, cost effective and high intensity in their operation in order to drive down the cost of producing renewable hydrogen fuels to an even more competitive level."
The findings are published in the March 2016 journal Science.
