The so-called hydrogen economy – based around storage and usage of hydrogen rather than oil products as an energy carrier – has always stumbled because of lack of availability of hydrogen. Currently, its major sources all use fossil fuels as their source, which is counter-productive. Splitting water into hydrogen and oxygen uses electricity, which must be carbon neutral if the goal of reducing carbon emissions is to be met, and depends on the use of catalysts to reduce the energy needed to split the stable water molecule. The most efficient catalysts are based on costly platinum and only work under acidic conditions. Many researchers have been trying to solve this problem, and a team from the University of Toronto believes it may have found a solution.
In a paper in Nature Energy, engineers working with Prof Ted Sargent describe how the electrolysis catalyst is based on copper, nickel and chromium, all of which are more abundant and less costly than platinum. "But what's most exciting is that it performs well under pH-neutral conditions, which opens up a number of possibilities," said Cao-Thang Dinh, a postdoctoral student and co-lead author with Prof Sargent.
Because of the need for low pH, platinum catalysts cannot be used to electrolyse seawater, which is the most abundant source of water on earth but is pH neutral. It needs to go through a desalination process first, which raises the costs further. Using the new copper-nickel-chromium catalyst would enable seawater to be used without so much prior treatment.
But that’s not all, explained team member Garcia de Arquer. "There are bacteria that can combine hydrogen and CO2 to make hydrocarbon fuels," he said. "They could grow in the same water and take up the hydrogen as it's being made, but they cannot survive under acidic conditions."
This possibility makes discovery eligible for the NRG COSIA Carbon X-Prize, which is aimed at developing ways of using renewable energy to convert waste CO2 into fuels or other value-added products. A team from Prof Sargent’s lab is among the five finalists in the international competition for the $7.5 million grand prize.
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