Solar water-splitting method to provide clean energy

Researchers from Rice University have demonstrated an efficient new way to capture the energy from sunlight and convert it into clean, renewable energy by splitting water molecules.

The technology relies on a configuration of light-activated gold nanoparticles that harvest sunlight and transfer solar energy to highly excited electrons, which scientists sometimes refer to as "hot electrons".

"Hot electrons have the potential to drive very useful chemical reactions but they decay very rapidly and people have struggled to harness their energy," said lead researcher Isabell Thomann, assistant professor at Rice University.

For example, most of the energy losses in today's best photovoltaic solar panels are the result of hot electrons that cool within a few trillionths of a second and release their energy as wasted heat.

Capturing these high-energy electrons before they cool could allow solar-energy providers to significantly increase their solar-to-electric power-conversion efficiencies and meet the goal of reducing the cost of solar electricity.

In the light-activated nanoparticles, light is captured and converted into plasmons, waves of electrons that flow like a fluid across the metal surface of the nanoparticles.

Plasmons are high-energy states that are short-lived but researchers have found ways to capture plasmonic energy and convert it into useful heat or light.

Plasmonic nanoparticles also offer one of the most promising means of harnessing the power of "hot electrons".

"Utilising hot electron solar water-splitting technologies were on par with considerably more complicated structures that also use more expensive components," Thomann said.

"We are confident that we can optimise our system to significantly improve upon the results we have already seen," he added.

The findings were described in the American Chemical Society journal Nano Letters.