Making hydrogen isn’t terribly difficult, but hydrogen isn’t a loner. It’s most abundant in water, but isolating hydrogen from H2O creates a toxic byproduct -- carbon dioxide.
Now scientists at the U.S. Department of Energy’s Argonne National Laboratory outside Chicago have developed what they call a “hydrogen generator,” a microscopic device that uses light and graphene to increase the production of pure hydrogen.
In the process, they also learned about a previously unknown property of graphene, a honeycomb sheet of carbon atoms one-atom thick. They found that graphene not only gives and receives electrons, but can also transfer them into another substance. Their research was published in the journal ACS Nano.
Generating pure hydrogen is a major breakthrough because the current method is to separate it from water using natural gas, a fossil fuel, to react with high-temperature steam to strip away hydrogen atoms for use as hydrogen fuel. But this process releases the greenhouse gas CO2 into the Earth’s atmosphere.
Argonne’s generator, however, shows that hydrogen can be produced without burning any fossil fuels.
So far the generator is small, even smaller than the diameter of spider silk, but if it can be enlarged, enough hydrogen can be produced to power cars and even power generators – an infinitely cleaner alternative to oil or coal because hydrogen fuel emits only water vapor.
Elena Rozhkova, a chemist at Argonne, said in a statement that the Argonne team was inspired by the function of a protein known to turn light into energy. Certain single-celled organisms are known to use a protein called bacteriorhodopsin (bR) to absorb sunlight and pump protons through a membrane, creating a form of chemical energy.
At the same time, she explained, water can be split into oxygen and hydrogen not only with natural gas but also by combining bR with titanium dioxide and platinum, then exposing these substances to ultraviolet light.
The trouble is that ultraviolet light makes up only 4 percent of the solar spectrum, Rozhkova said, so the Argonne researchers needed to find a new material that would produce more hydrogen using other lights from the solar spectrum.
What they found was graphene, which has enough surface area to move electrons quickly and evenly, and serves as a platform where biological components such as bR can not only survive but also make contact with the titanium dioxide. In short, graphene is very strong, very light and one of the best conductors of electricity known to science.
In the mini-hydrogen generator, both the bR protein and the graphene absorb visible light, creating electrons that are transmitted to the titanium dioxide, which thereby becomes sensitive to visible light. Meanwhile, light from the green end of the solar spectrum makes the bR protein move protons to the platinum particles on the titanium dioxide.
And this convergence on the platinum produces hydrogen – and nothing but hydrogen.
By Andy Tully of Oilprice.com
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Andy Tully is a veteran news reporter who is now the news editor for Oilprice.com