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A MIT research team created the world's first cost-effective, artificial leaves in 2011.  A functioning artificial leaf was invented more than ten years ago but it was highly unstable and expensive to produce. In 2013, the same team further developed their invention to enable the leaves to self-heal and to work even with dirty water.  

The artificial leaf is a wafer of silicon coated in a catalyst that, when exposed to sunlight and water, breaks down water into its hydrogen and oxygen components. However, bacteria can build up on the artificial leaf’s surface and will eventually terminate the production process. This problem was overcame by developing catalysts that artificial leaf actually heal themselves, meaning the process can work with dirty water.

Now, researchers at Harvard, led by the original team leader from MIT, Dr. Daniel Nocera have follow on to develop the "bionic leaf 2.0". Dr Nocera worked with Pamela Silver, Professor of Biochemistry and Systems Biology at Harvard Medical School on the latest research. The new invention greatly increases the efficiency of the photosynthesis process well beyond Mother Nature's own capabilities.  The Harvard scientists were also able to use sunlight to produce liquid fuels for the first time. This break through is tremendous considering that one of the main challenges of solar power system is how to improve the effectiveness and efficiency of the energy storage system.

The bionic leaf 2.0 works by absorbing solar energy and using the energy to split water molecules into their component gases, hydrogen and oxygen. These gases are then harvested to be used in fuel cells to generate electricity in the original invention. In bionic leaf 2, but now, with the help of an engineered bacteria, the hydrogen can be used to produce liquid fuels.

Where this latest device beats the efficiency of previous tests – and nature itself – is down to the catalyst that produces the hydrogen. In earlier versions, the nickel-molybdenum-zinc alloy catalyst used to produce the hydrogen also created reactive oxygen species, molecules that will destroy the working bacteria’s DNA. To prevent that, researchers had to use a high system voltage, resulting in reduced efficiency. The new cobalt-phosphorous alloy catalyst does not create reactive oxygen species, so the system voltage can be lowered, and that led to a huge increase in efficiency."

While the system can be further improved in term of efficiency, the research team is already considering commercial applications. They also plan to develop the technology for use as a cheap source of renewable energy, which could power individual homes in poor developing countries.