Reduction of carbon dioxide during the synthesis of metal nano-particles in water

An effort was made to synthesize “carbon-free” metal (Fe0, Co0, Ni0) nano-particles via the reduction of their salts with BH4− in aqueous solutions. Surprisingly it was found that when the synthesis is carried out in the presence of CO2, e.g., in aerated solutions, the CO2 is catalytically reduced by BH4− on the surface of the metal particles. Carbon-free metals can be prepared by reduction under an inert atmosphere. Thus metal surfaces might have acted as catalysts for CO2 fixation, probably via the initial formation of carbon clusters, in the reductive atmosphere in the prebiotic era.