A catalyst for ‘greener’ hydrogen production

University of Delaware

A RESEARCHER at the University of Delaware (UD), US has patented a process that could enable greener production of hydrogen. The process uses electricity and a copper-titanium (Cu-Ti) catalyst to make hydrogen from water.

Hydrogen is an energy carrier and can be used to power fuel cells in vehicles, buildings, and other infrastructure. It can also be used to upcycle biomass, such as straw and grasses, into high-value chemicals to produce a range of products, such as  plastics, paint, and personal care items. However, using hydrogen for these purposes is challenged by the unsustainable methods required for hydrogen production. Currently, the main processes for production use fossil fuels and produce carbon dioxide.

Researchers at the lab of Feng Jiao, Associate Professor of Chemical and Biomolecular Engineering at UD, discovered a Cu-Ti alloy to be amongst only a few non-precious, metal-based catalysts suited to enabling water electrolysis. Water electrolysis uses an electric current to decompose water into hydrogen gas and oxygen.

The catalyst can  produce hydrogen at a rate twice as high as the current state-of-the-art platinum catalyst and in comparison, the overpotential is reduced by 40%. Overpotential is a key metric of electrochemical hydrogen evolution catalyst performance, explained Feng Jiao. It can be thought of as the difference in energy required to produce the same amount of hydrogen, he said.

The process can operate at near room-temperature (21–80°C), which increases the catalyst’s energy efficiency, and could greatly lower the capital cost for industrial systems. In addition, copper and titanium are considered relatively abundant and are inexpensive compared to precious metals typically required for the process.

Copper alone is not an effective catalyst for the water electrolysis process, but the addition of titanium creates unique active sites that enable hydrogen atoms to interact more strongly with the catalyst, in a way comparable to more expensive platinum-based catalysts. 

Jiao added: “With our new catalyst and advances in membrane technology which allow us to use far less expensive components in alkaline conditions, there is an opportunity to change the way we make hydrogen at scale.”

He said: “With our most recent paper [published in ACS Catalysis], we've not only established the high performance of nanoporous Cu-Ti but also the fundamental characteristics which drive its activity. At this point, we think it's time to take this catalyst out of the research lab and to start exploring commercial avenues.”

Future work includes scaling the electrolysis equipment for commercial use, Feng told a university reporter. Researchers also plan to test the stability of the catalyst and identify the Cu-Ti composition that provides the best balance between cost and performance.

This work was funded by the National Science Foundation, NASA, and the US Department of Energy.

Inciting research

The lab research focus had initially been the conversion of carbon dioxide into useful chemicals, such as ethylene (for synthesis fuel production), or ethylene, for the production of polymers.

A project funded by the National Science Foundation and NASA focussed on the conversion of carbon dioxide to oxygen – which NASA could employ in deep space. The group was experimenting with different metal catalysts for this reaction when they discovered the effectiveness of a Cu-Ti alloy in the electrolysis of water.

The researchers now plan to shift focus back towards carbon dioxide.

“At the moment, we are focussing on electrocatalysts for converting carbon dioxide waste into chemicals and fuels,” said Jiao. “Hydrogen is also generated during that process, and so the insights we gained through working with the Cu-Ti alloys have been valuable for tuning catalyst activities.”

ACS Catalysis: http://doi.org/gfjnqx

Nature Communications: http://doi.org/f68dkz