New water-splitting materials for cheap production of clean energy

Posted 5 June 2017

UNSW chemists have invented a new catalyst for splitting water with an electrical current – to efficiently produce hydrogen fuel.

Using metal organic frameworks, Associate Professor Chuan Zhao and Drs Sheng Chen and Jingjing Duan created an electrocatalyst that drives the two reactions required for separating water into its constituent molecules, hydrogen and oxygen. Splitting water usually requires two different catalysts.

Until now, most metal organic frameworks, or MOFs, were considered to be poor conductors – so, not useful for electrochemical reactions. They are typically made into a bulky form, which means the active catalytic sites are deeply embedded inside the porous material, where it is difficult for the water to access.

“With nanoengineering, we made a unique MOF structure that solves the big problems of conductivity, and access to active sites,” says Zhao, who led the study just published in the journal, Nature Communications.

By creating MOF arrays that are ultrathin they were able to expose the pores, and increase the surface area for electrical contact with water. These MOF electrocatalysts were made of abundant, non-precious metals like nickel, iron and copper.

The team was excited about how well their MOF electrodes performed. Compared to other water-splitting electrocatalysts reported to date, their 2-dimensional MOF is among the most efficient.

Hydrogen is a great carrier for renewable energy because it is abundant, generates zero emissions, and is much easier to store than other energy sources, like solar or wind energy. But the most efficient water splitting catalysts reported so far are often made with precious metals, like platinum and ruthenium.

MOFs, are a family of porous materials with demonstrated potential for a huge range of applications, including, fuel storage, drug delivery, and carbon capture, to name just a few.

Zhao’s team now demonstrate that MOFs can be highly conductive too, introducing a host of new applications for this class of material. As ultrathin structures, MOFs can be efficient for water splitting, and other electrochemical reactions.

“It’s ground-breaking – it challenges a common concept that MOFs are inert electrocatalysts,” says Zhao, who has been awarded a Future Fellowship from the Australian Research Council in the recent funding round.

 

Read this story on UNSW Science News