Jan. 21 (UPI) -- Scientists have discovered a molecule that can take advantage of the entire visible spectrum of sunlight. The molecule can both efficiently absorb sunlight and operate as a catalyst, triggering the conversion of solar energy into hydrogen, which can be used as fuel.
In a new paper, published this week in the journal Nature Chemistry, scientists suggest the novel molecule can be used to build more efficient solar cells and accelerate the transition to alternative, climate-friendly fuels like hydrogen.
"The whole idea is that we can use photons from the sun and transform it into hydrogen," lead researcher Claudia Turro, a chemistry professor at Ohio State University, said in a news release. "To put it simply, we are saving the energy from sunlight and storing it into chemical bonds so it can be used at a later time."
Turro and her colleagues were able to find a particle that absorbs the sun's low-energy wavelengths, the infrared portion of the spectrum.
"What makes it work is that the system is able to put the molecule into an excited state, where it absorbs the photon and is able to store two electrons to make hydrogen," Turro said. "This storing of two electrons in a single molecule derived from two photons, and using them together to make hydrogen, is unprecedented."
Most previous efforts to make full use of the sunlight spectrum have focused on ultraviolet light, and most relied on catalysts made of two or more molecules to convert solar energy into hydrogen. Attempts to use a single-molecule catalyst proved inefficient.
Scientists found that a single rhodium molecule can absorb the entirety of the visible light spectrum, from infrared to ultraviolent, and can catalyze the conversion of low-energy wavelengths into hydrogen without losing much energy.
To do all this, the molecule must be in an excited state. In the lab, scientists used an LED to excite rhodium molecules suspended in an acid solution.
"I think the reason it works is because the molecule is difficult to oxidize," Turro said. "And we have to have renewable energy. Just imagine if we could use sunlight for our energy instead of coal or gas or oil, what we could do to address climate change."
Scientists are now working to find a molecule that behaves similarly to rhodium, as the rare metal is expensive to process. Researchers also want to find a way to make the single-molecule catalyst produce hydrogen for a longer period of time.