If only it were so simple. What plants actually achieve is the synthesis of sugar by joining carbon dioxide to water, using enrgy from light. I won't start explaining the biochemistry of it because it'll be easy enough to find on the web.

Simulating it would be a clever way of getting rid of carbon dioxide from the air... wouldn't it? A lot of clever people are trying to find efficient ways to do just that.

Most timely, a BBC item about an article in "Science" from 3 days ago, concerning essentially man-made photosynthesis.

http://www.bbc.co.uk/news/science-environment-12051167

The photosynthesis of plants involves hydrogen,oxygen and carbon dioxide.It is very unlikely that humans could devolop photosynthesis in the same way as plants do since they don't contain the required organs or the same cells.Earlier I said in the same way as plants because humans have some processes very simialar to photosynthesis in their digestive systems.

Plants do NOT separate oxygen from CO2. All of the oxygen in photosynthesis comes from the photolysis of water. This can be shown by isotope labeling of the components.

While great strides have been made in using light as an energy source to synthesize organic molecules, they will not try to replicate photosynthesis. There are cheaper and simpler chemical approaches to achieve the same results.