Scientists split water into hydrogen, oxygen utilizing light, nanoparticles

December 17, 2013 by  
Filed under Solar Energy Tips

According to a December 15 news release from the University of Houston (UH), researchers there have discovered a catalyst that can rapidly separate hydrogen and oxygen from water using the sun’s rays and cobalt oxide nanoparticles.  The discovery could potentially create a clean and renewable source of energy.

The complete research findings appear online in Nature Nanotechnology, in an article entitled, “Efficient solar water-splitting using a nanocrystalline CoO photocatalyst.”

According to Jiming Bao, lead author of the paper and an assistant professor in the Department of Electrical and Computer Engineering at UH, the investigation yielded a new photocatalyst and established the potential of nanotechnology in engineering a material’s property.

Since the 1970s, Bao said, photocatalytic water-splitting experiments have been attempted, but this was the first experiment to use cobalt oxide and neutral water under visible light at a high energy exchange efficiency without co-catalysts or sacrificial chemicals.  The project drew from the expertise of researchers from UH, Sam Houston State University, the Chinese Academy of Sciences, Texas State University, Carl Zeiss Microscopy LLC, and Sichuan University.

The researchers primed the nanoparticles in two ways: femtosecond laser ablation, and mechanical ball milling.  Bao said that although there were some notable differences, both methods worked equally well.

The experiments used different sources of light, ranging from a laser to white light simulating the solar spectrum.  Bao also said he would anticipate the reaction to work equally well using natural sunlight.

As soon as the nanoparticles are added and light is applied, the water splits into hydrogen and oxygen almost instantly, producing twice as much hydrogen as oxygen, as expected from the 2:1 hydrogen to oxygen ratio in water molecules.

The experiment demonstrates potential as a viable source of renewable fuel; however, with a solar-to-hydrogen efficiency rate of approximately 5 percent, the conversion rate is still too low to be commercially viable.  Bao recommended a more practicable efficiency rate would be approximately 10 percent, signifying that 10 percent of the incident solar energy will be converted to hydrogen chemical energy by the process.

Additional issues wait to be resolved, including reducing costs and extending the lifespan of cobalt oxide nanoparticles, which the researchers discovered became deactivated after approximately one hour of reaction.

Bao said that the ultimate goal of the experiments is that they will lead to future scientific investigations, including discovering why cobalt oxide nanoparticles have such a short lifespan, and questions concerning chemical and electronic properties of the material.

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