Can Hydrogen Fuels Be Produced With Solar Energy? New Tech Advances Include an ‘Artificial Leaf’

Two studies published this week explore innovative ways to produce hydrogen fuels through solar energy, one via a catalyst and another via a solar-powered artificial leaf device. Both methods mimic photosynthesis to produce hydrogen in more efficient and sustainable ways.

Researchers at the University of Michigan developed a catalyst to split water into oxygen and hydrogen. The catalyst, which has reached 9% efficiency, is about 10 times more efficient than other similar methods of solar water-splitting.

The study, published in the journal Nature, includes two technological advances to make the more efficient photocatalytic water-splitting. One is a smaller, self-heating semiconductor that can withstand the light of an equivalent to 160 suns. Reducing the semiconductor’s size also makes the process less expensive.

“We reduced the size of the semiconductor by more than 100 times compared to some semiconductors only working at low light intensity,” Peng Zhou, University of Michigan research fellow and first author of the study, said in a statement. “Hydrogen produced by our technology could be very cheap.”

Secondly, the team used a higher energy part of the solar spectrum in order to split the water, while they relied on a lower energy part of the solar spectrum for heat needed for the reaction.

Moving forward, the researchers plan to further improve the efficiency of the process and ultimately create ultrahigh purity hydrogen that can be used directly in fuel cells.

Meanwhile, researchers at Ecole Polytechnique Fédérale de Lausanne (EPFL) have created a solar-powered artificial leaf that similarly mimics photosynthesis in order to harvest moisture in the air and convert it into hydrogen fuel.

The engineers developed a transparent, porous electrode from felt wafers made with a type of glass wool. The felt wafers are coated with a thin, transparent fluorine-doped tin oxide, an excellent conductor that is also easy to scale up.

Then the felt wafers are coated again with a thin layer of semiconductor materials that absorb sunlight. While the felt wafer can absorb sunlight and produce hydrogen on its own, the researchers also built a small chamber around the coated wafer with a membrane that could separate the hydrogen produced during the reaction for measuring.

This study, published in Advanced Materials, didn’t cover efficiency of the process, although the maximum theoretical efficiency of the wafers is about 12%.

Still, the findings represent a potential for scalable methods to produce hydrogen from solar power.

“To realize a sustainable society, we need ways to store renewable energy as chemicals that can be used as fuels and feedstocks in industry,” EPFL chemical engineer Kevin Sivula and principal investigator of the study, said in a statement. “Solar energy is the most abundant form of renewable energy, and we are striving to develop economically competitive ways to produce solar fuels.”