Numerous schemes have been described as artificial photosynthesis.  
*Photocatalytic water splitting, the conversion water into hydrogen and oxygen:
This scheme is the simplest form of artificial photosynthesis conceptually, but has not been demonstrated in any practicable way.
*Light-driven carbon dioxide reduction, the conversion water, carbon dioxide into carbon monoxide or organic compounds and oxygen.  In the conceptually simplest manifestation, this process gives CO:
Related processes give formic acid (HCO2H):
Variations might produce formaldehyde or, equivalently, carbohydrates:
These processes replicate natural carbon fixation.
Because of the socio-economic implications, Artificial photosynthesis is very topical, despite the many challenges. 
  Ideally the only inputs to produce such solar fuels would be water, carbon dioxide, and sunlight. The only by-product would be oxygen. 
 by using direct processes,