Scientists closer to perfecting hydrogen-producing artificial leaf

Scientists are a step closer to achieving perfection in engineering a solar energy-based artificial leaf capable of generating hydrogen as an alternative source of energy.

In a recent early online edition of Nature Chemistry, scientists at Arizona State University College of Liberal Arts and Science (ASU), along with colleagues at Argonne National Laboratory, 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

Hydrogen is an important fuel in itself and serves as an indispensable reagent for the production of light hydrocarbon fuels from heavy petroleum feed stocks.

Society requires a renewable source of fuel that is widely distributed, abundant, inexpensive and environmentally clean.

Society needs cheap hydrogen.

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

"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 namely hydrogen and oxygen."

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, reports Science Daily.

"We looked in detail and found that nature had used an intermediate step," said Moore.

"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.

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.