Bionic Leaf is more efficient than photosynthesis

If you remember elementary school science, photosynthesis is the process used to create energy by plants. Scientists Daniel Nocera and Pamela Silver from Harvard have created what they call a bionic leaf that is able to use solar energy to split water molecules and hydrogen-eating bacteria to produce liquid fuel. The system is said to be more efficient than natural photosynthesis.

Nocera is the Patterson Rockwood Professor of Energy at Harvard University and Silver is the Elliott T. and Onie H. Adams Professor of Biochemistry and Systems Biology at Harvard Medical School. "This is a true artificial photosynthesis system," Nocera said. "Before, people were using artificial photosynthesis for water-splitting, but this is a true A-to-Z system, and we've gone well over the efficiency of photosynthesis in nature."

Silver says that the platform they have created can be used to create any downstream carbon-based molecule giving the system versatility. The latest version is called "bionic leaf 2.0" and builds on previous work by Nocera, silver, and other scientists. One challenge that the team has to overcome was caused by the nickel-molybdenum zinc alloy that created reactive oxygen species, which are molecules that attacked and destroyed the bacteria's DNA.

"For this paper, we designed a new cobalt-phosphorous alloy catalyst, which we showed does not make reactive oxygen species," Nocera said. "That allowed us to lower the voltage, and that led to a dramatic increase in efficiency."

The system is able to convert solar energy to biomass with 10% efficiency. The fastest-growing plants convert solar energy to biomass at around 1%. Nocera says that while there may be room to improve efficiency, the system is efficient enough as it is to consider possible commercial applications. The research in this project was sponsored by the Office of Naval Research, Air Force Office of Scientific Research, and the Wyss Institute for Biologically Inspired Engineering.

SOURCE: Harvard