text: 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,