As work to make solar power more efficient and affordable proceeds – important work that can boost solar’s share of the electricity we consume – some scientists are off on an entirely different research path. This is the effort to turn sunlight into fuel.
It’s a path that figures to be long and winding before reaching a marketable payoff, yet signs of progress continue to emerge. The latest is from the University of North Carolina, where scientists at the Energy Frontier Research Center report they are producing hydrogen using the power of the sun.
True, we began hearing about “major breakthroughs” on this front at least five years ago, but incremental progress is still important in building the stable and economically viable systems that can make the move from laboratory to real world – and that appears to be what we’re talking about here. (We saw similar headway reported last fall from the government’s Joint Center for Artificial Photosynthesis in Berkeley, where new advances in combining light-absorption and fuel-producing catalyst structures and functions are unfolding.)
Here’s the basic outline of UNC chemist Tom Meyer’s work, according to the university:
His design has two basic components: a molecule and a nanoparticle. The molecule, called a chromophore-catalyst assembly, absorbs sunlight and then kick starts the catalyst to rip electrons away from water. The nanoparticle, to which thousands of chromophore-catalyst assemblies are tethered, is part of a film of nanoparticles which shuttles the electrons away to make the hydrogen fuel.
Meyer’s challenge was to keep the system from “crashing” – “either the chromophore-catalyst assembly kept breaking away from the nanoparticles or … the electrons couldn’t be shuttled away quickly enough to make hydrogen,” UNC said.
That’s where Greg Parsons at North Carolina State University lended a hand:
Meyer turned to the Parsons group at NCSU to use a technique that coated the nanoparticle, atom by atom, with a thin layer of a material called titanium dioxide. By using ultra-thin layers, the researchers found that the nanoparticle could carry away electrons far more rapidly than before, with the freed electrons available to make hydrogen. They also figured out how to build a protective coating that keeps the chromophore-catalyst assembly tethered firmly to the nanoparticle, ensuring that the assembly stayed on the surface.
Cool as this system is – and Meyer believes that existing technologies can put it in reach for real-world use – his more ambitious goal, as with the Berkeley researchers, is to use the process to create hydrocarbon fuels that can go in your gas tank.