Scientists take step closer towards creating 'artificial leaf'

Arizona State University scientists, along with colleagues at Argonne National Laboratory, have reported advances toward perfecting a functional artificial leaf.

Designing an artificial leaf that uses solar energy to convert water cheaply and efficiently into hydrogen and oxygen is one of the goals of BISfuel - the Energy Frontier Research Center, funded by the Department of Energy, in the Department of Chemistry and Biochemistry at Arizona State University.

"Initially, our artificial leaf did not work very well, and our diagnostic studies on why indicated that a step where a fast chemical reaction had to interact with a slow chemical reaction was not efficient," ASU chemistry professor Thomas Moore, said.

"The fast one is the step where light energy is converted to chemical energy, and the slow one is the step where the chemical energy is used to convert water into its elements viz. hydrogen and oxygen," the researcher said.

The researchers took a closer look at how nature had overcome a related problem in the part of the photosynthetic process where water is oxidized to yield oxygen.

The researcher said, this intermediate step involved a relay for electrons in which one half of the relay interacted with the fast step in an optimal way to satisfy it, and the other half of the relay then had time to do the slow step of water oxidation in an efficient way.

They then designed an artificial relay based on the natural one and were rewarded with a major improvement.

Seeking to understand what they had achieved, the team then looked in detail at the atomic level to figure out how this might work.

They also found subtle magnetic features of the electronic structure of the artificial relay that mirrored those found in the natural system.

Not only has the artificial system been improved, but the team understands better how the natural system works.

This will be important as scientists develop the artificial leaf approach to sustainably harnessing the solar energy needed to provide the food, fuel and fiber that human needs are increasingly demanding.

The study was published in the journal Nature Chemistry.