Eoin Treacy's view -
In conventional water splitters, the hydrogen and oxygen catalysts often require different electrolytes with different pH — one acidic, one alkaline — to remain stable and active. “For practical water splitting, an expensive barrier is needed to separate the two electrolytes, adding to the cost of the device,” Wang explained.
“Our water splitter is unique because we only use one catalyst, nickel-iron oxide, for both electrodes,” said graduate student Haotian Wang, lead author of the study. “This bi-functional catalyst can split water continuously for more than a week with a steady input of just 1.5 volts of electricity. That’s an unprecedented water-splitting efficiency of 82 percent at room temperature.”
Wang and his colleagues discovered that nickel-iron oxide, which is cheap and easy to produce, is actually more stable than some commercial catalysts made of expensive precious metals.
The key to making a single catalyst possible was to use lithium ions to chemically break the metal oxide catalyst into smaller and smaller pieces. That “increases its surface area and exposes lots of ultra-small, interconnected grain boundaries that become active sites for the water-splitting catalytic reaction,” Cui said. “This process creates tiny particles that are strongly connected, so the catalyst has very good electrical conductivity and stability.”
The challenge for a hydrogen fuelled economy has always been in delivering the gas at an acceptable price. More recently the fact the majority of hydrogen is produced from natural gas has acted against it as a potential solution because of environmental concerns. Technological innovation has the potential to change that scenario if a scalable, low Energy solution can be delivered.
Toyota is making a big bet on hydrogen fuel cells with its Mirai vehicle due for release this summer. Removing a reliance on natural gas from the fuel cycle would represent a major selling point for the vehicles.
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