A team of researchers at the University of Houston, attempting to split water using light (an ongoing task since the 1970’s), made the breakthrough by using cobalt oxide nanoparticles
A manipulation of matter at an atomic and molecular scale, nanotechnology is fast becoming one of the most important drivers of technological growth, with a wide spectrum of applicable uses, one of which is in the engineering of a material’s property.
In this particular case, the team used the aforementioned cobalt oxide nanoparticles to split the water into hydrogen and oxygen. They accomplished this by preparing the nanoparticles using two methods: femtosecond laser ablation and mechanical ball milling. Despite differences, the team lead, Dr. Jiming Bao, noted that both worked equally well.
When the nanoparticles are added and light applied, the water separates into hydrogen and oxygen almost immediately, producing twice as much hydrogen as oxygen. “This is as expected from the 2:1 hydrogen to oxygen ratio in H2O water molecules,” Bao said.
Although photocatalytic water-splitting experiments have been a scientific pursuit for about 40 years now, Bao mentioned that “this was the first to use cobalt oxide and the first to use neutral water under visible light at a high energy conversion efficiency without co-catalysts or sacrificial chemicals.”
The successful experiment has potential as a source of renewable fuel, but there are a few roadblocks to navigate before creating a satisfactory final result. With a a solar-to-hydrogen efficiency rate of around 5%, the conversion rate is still at a level way too low to be commercially viable. Bao suggested a more realistic efficiency rate would be around 10%.
Lowering cost to a realistic price point is another major concern, along with finding ways to extend the lifespan of cobalt oxide nanoparticles, which the researchers found became deactivated after about an hour of reaction.
“It degrades too quickly,” said Bao
The next step in the process is figuring out exactly why cobalt oxide nanoparticles have such short lifespans, in addition to learning more about the chemical and electronic properties of the material.
There is still much to do, but this breakthrough has certainly helped shorten the timeline.