It takes 94 k-cal of energy per mol of CO2 (about 44g) to separate the O2 from the carbon atom.

 

Some work is being done on the Counter-Rotating-Ring Receiver Reactor Recuperator which is using solar power to make a fuel.

 

I'm not interested in a useful by product, I just want to extract the O2 with sunlight and leave the carbon. Is there possibly a nanoprocess using thin film technology and solar panels? Consider that the high temperatures used for bubble jet printing was found by accident in the semiconductor industry.

I just want to extract the O2 with sunlight and leave the carbon.

Grow plants and make charcoal.

Oh I want to do it on non-arable land so without water.