The collaborative research among three institutions, the California Institute of Technology, St. Andrews University (Scotland), and Robert Gordon University (Scotland) resulted in the synthesis and characterization of composite catalytic systems composed of earth-abundant metal oxide semiconductors, mixed metal oxide semiconductors, coupled with carbon nitride for the reduction of carbon dioxide into hydrogen carbons injunction with the reduction of protons and water to produce hydrogen.   The various composite catalysts were able to split water photochemically into hydrogen and oxide, to reduced carbon dioxide into methane, ethane, propane, butane, ethene, propene, butene, formate, oxalate, and methanol.  A composite catalyst consisting of multi-walled sodium titanate nanotubes, nano-particle elemental copper embedded in the walls of the nanotube base support, and nano-particle cadmium sulfide as a light-absorbing semiconductor was shown to be able to simply use CO₂, water, and light under-illumination with visible light to produce methane, ethane, and propane along with the corresponding alkenes.  Higher reactivity was obtained by increasing the non-stoichiometric fraction of sodium in the multi-walled titanate nanotubes.  Results of this collaborative project illustrate approaches to achieve artificial photosynthesis using earth-abundant inorganic materials to produced useful hydrocarbons for chemical synthesis, for energy production, and for carbon dioxide capture and recycling into useful materials.  With increased photo-efficiencies the use of composite inorganic materials for CO₂ capture and transformation in to useful byproducts may have a significant impact on reducing worldwide carbon footprints, less the impact of increasing CO₂ concentrations in the atmosphere and lead to greater energy and environmental sustainability.

Last Modified: 07/18/2014
Modified by: Michael R Hoffmann