Velu Jeyalakshmi

Application of photo catalysis for mitigation of carbon dioxide

Photo catalytic reduction of carbon dioxide by water or artificial photosynthesis to yield hydrocarbons (methane and methanol, etc., termed “solar fuels”) is being studied extensively, with the twin objectives of developing an effective means of limiting atmospheric CO2 levels and evolving a sustainable alternative route for production of fuels and chemicals. This short review covers the origin and thermodynamic and kinetic features of the process, the basic photocatalytic principles involved, the rationale behind the choice of different catalysts and their performance, the effect of process conditions, the effect of the structural and photophysical properties of the different catalysts on their performance, mechanistic pathways, surface transformations, challenges involved in the practical application of the process, and future directions for research.

Visible light driven reduction of carbon dioxide with water on modified Sr3Ti2O7 catalysts

Layered perovskite type Sr3Ti2O7 catalysts, doped with N, S and Fe have been prepared by modified polymer complex method, characterized and evaluated for photo reduction of CO2 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 S6+ and Fe as Fe3+ 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 Sr3Ti2O7 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. Sr3Ti2O7 co-doped with N, S and Fe together, displays maximum apparent quantum yield for CO2 reduction products.