Nanotechnology & Photosynthesis

It is widely known that we are running out of fossil fuels. Researchers have been trying to find alternative means of generating energy such solar power. While silicon photovoltaic cells forming solar panels have been used for decades, its efficiency is still not very large. Thus, other methods are being investigated. One of them is the use nanotechnology in a bottom-up approach similar to natural photosynthesis, where engineered nanostructures are used for the capture and conversion of light into usable energy.

The system tries to mimic the essence of natural photosynthesis where chlorophyll molecules in plants form a receptor that collects light energy from the sun. After that, the energy is used to drive a charge separation reaction at a reaction center which produces both an electron and an "electron hole" where the electron was removed from. Next, the free electron is used to produce usable electrochemical energy that is then stored in adenosine triphosphate molecules, also known as ATP.

Recently, scientists were successful in conducting the same fundamental process that occurs in natural photosynthesis but with simpler nanostructures. Researchers at Arizona State University created a hexad, or six-part nanoparticle made of four zinc tetraarylporphyrin molecules, (P_ZP)₃-P_ZC, a free-base porphyrin, and a fullerene molecule, P-C₆₀. This material is capable of forming the basic steps of photosynthesis such as light gathering, charge separation, and recombination.

When one of the three outer zinc porphyrin is excited by light energy, the energy is transferred through the central zinc porphyrin to the free-base porphyrin, which is connected to the fullerene. The energy causes the free-base porphyrin and fullerene to be excited in conjunction with electron transfer and charge separation take place. The free-base porphyrin and fullerene then decay, resulting in recombination and an output of electrochemical energy.

You can also look up the group work on: http://web.stanford.edu/group/mota/education/Physics%2087N%20Final%20Projects/Group%20Gamma/photo.htm

Drawbacks of this method include lower efficiency than the natural process. However, one of the reasons that the technology is being pursued is that it has also suggested that artificial photosynthesis on a large industrial scale could reverse global warming since the process consumes carbon dioxide and releases oxygen, imagine how cool is that?