The photoassisted reaction of gaseous water and carbon dioxide adsorbed on the SrTiO3 (111) crystal face to form methane

The photosynthetic reaction of gas phase water and carbon dioxide molecules adsorbed onto strontium titanate surfaces that are in contact with platinum foils is reported. The dominant reaction product detected at 15 torr partial pressures of the reactant gases is methane. The reaction takes place without any externally applied potential (between the foil and SrTiO₂) and in the absence of liquid electrolyte, when the clean, reduced SrTiO₃ (111) crystal face in illuminated with light of energy greater than the band gap. A thermal process, which produces methane, when the SrTiO₃P?t sandwich is healed in CO₂ and water, is also observed. The photo and thermal processes are easily distinguished by the use of filters.