Enhanced photocatalytic reduction of CO2 using CdS/Mn2O3 nanocomposite photocatalysts on porous anodic alumina support with solar concentrators

Abstract

Photocatalytic reduction of CO2 has gained interest due to dual benefits of reduction of global warming and production of synthetic fuels. In this work, we report photochemical reduction of CO2 using CdS and CdS/Mn2O3 nanocomposites as photocatalyst supported on porous anodic alumnia (PAA) support. Incomplete anodization of an aluminum film substrate leaves a thin layer of aluminum in the middle that improves mechanical integrity and retain electrical conductivity of the support. The rod shaped crystals of CdS, grown on the support’s pore surface form a crumpled sheet like structure that helps in trapping of light energy incident on the catalyst surface. The photocatalytic reduction of CO2 was performed under the direct sunlight, using reflectors like flat mirrors, compound parabola, and concentrating Fresnel lens to direct solar radiation onto the catalytic surface. The combination of Fresnel lens as concentrator and CdS/Mn2O3 nanocomposite as the catalyst gave exceptional increase in the photocatalytic activity when compared with CdS alone, with a peak formation rate of 52.2 μmol/g.cat/hr of C2H5OH, 1392.3 μmol/g.cat/hr of HCOOH and H2 production at the rate of 2766 μmol/g.cat/hr.