Visible light driven reduction of carbon dioxide with water on modified Sr sub(3)Ti sub(2)O sub(7) catalysts

Layered perovskite type Sr sub(3)Ti sub(2)O sub(7) catalysts, doped with N, S and Fe have been prepared by modified polymer complex method, characterized and evaluated for photo reduction of CO sub(2) in aqueous alkaline medium using UV-visible radiation. EDXA and XRD data reveal the incorporation of the dopants into the titanate matrix. The presence of N in substitutional and interstitial locations, S as S super(6+) and Fe as Fe super(3+) species are indicated by XPS analysis. DRS and photo luminescence studies show that the dopants form additional energy levels within the band gap, promoting visible light absorption and retarding recombination of the charge carriers. Morphological changes and smaller crystallites also minimize recombination. Layered structure of Sr sub(3)Ti sub(2)O sub(7) facilitates easy transport of charge carriers and separation of oxidation/reduction reaction centres. Structural, morphological and photo physical characteristics of doped catalysts improve the activity significantly. Sr sub(3)Ti sub(2)O sub(7) co-doped with N, S and Fe together, displays maximum apparent quantum yield for CO sub(2) reduction products.