Artificial leaf

Massachusetts Institute of Technology scientist Daniel Nocera's artificial leaf device, on a real leaf, is a step closer to making artificial photosynthesis possible. Credit: MIT, Photograph courtesy Dominick Reuter, MIT

Nature through evolution has become a great chemical factory that makes the most out the energy available. By far, most of the energy on Earth is the one coming from the Sun, from its light. The "invention" of photosyntheses goes to the very beginning of life on Earth. The consensus is the the Earth was born some 4.6 billion years ago and just 1.2 billion years after that the first bacteria having photosynthesis capability appeared. They absorbed infrared light (not the light used by vegetation today) and produced sulphur (rather than oxygen). At that time though, that was the best strategy for converting Sun energy into chemical energy that could be stored and used as need arose. 600 million years went by and cyanobacteria made their appearance and started to produce oxygen. Brown and red algae appeared only 1.2 billion years ago with some form of chlorophyll and the green algae, the first having the photosynthesis processes we see today in plants appeared just 750 million years ago. Today's plant ancestors made their appearance less than 500 million years ago.

Hence it took some 3 billion years to create that very sophisticated process that we find in leaves today.

It took a lot of time to discover the photosynthesis, it became somewhat clear in the second half of the XVIII century but the full chemical reactions involved in photosynthesis and the role of quantum mechanics that eventually clarified all aspects of the process required 150 more years.

After the phase of discovery and understanding research moved to the phase of emulation: creating photosynthesis in the lab and then perfecting it to improve its efficiency.  We are still in this phase, and making progress.

This lengthy introduction to emphasise the value of this news about the invention of an artificial leaf. The invention is reported in an article on Science.

The team of researchers at Harvard managed to obtain the separation of water molecules into hydrogen and oxygen using light by using as catalyst an alloy made of cobalt and phosphorous. This has resulted in in a yield that is 10 times better than the natural photosynthesis. The hydrogen is used to feed hydrogen eating bacteria to produce fuel.

The cobalt phosphorous alloy betters a previous alloy used by the same research team that was as effective but resulted in a type of oxygen production that killed the bacteria.

I am really amazed both at Nature and our growing capability of learning and do it better!

Author - Roberto Saracco

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