CH 4 Synthesis from CO 2 and H 2 O of an Electron Source over Rh-Ru Cocatalysts Loaded on NaTaO 3 :Sr Photocatalysts.

CO 2 reduction as an artificial photosynthetic system is a promising technology to produce green energies and chemicals because it uses light energy to convert H 2 O and CO 2 into valuable products such as CO, HCOOH, CH 3 OH, CH 4 , and preferably higher hydrocarbons. In photocatalytic reduction, water should be used as hydrogen and electron sources for CO 2 reduction. Moreover, CH 4 formation is an attractive and challenging topic because of the eight-electron-reducing product of CO 2 . Herein, we report the development of a new Rh-Ru cocatalyst decorated on an alkaline earth-doped NaTaO 3 surface for the photocatalytic CO 2 reduction to form CH 4 using water as an electron donor. CH 4 was obtained by a photocatalytic "uphill" reaction of CO 2 reduction using Rh-Ru cocatalyst-loaded NaTaO 3 :Sr, water, and CO 2 in an aqueous suspension system. About 10% of a selectivity (electronic efficiency) was obtained for CH 4 formation under ambient conditions accompanied with O 2 evolution of the oxidation product of H 2 O.