Continuous Photocatalytic Reduction of CO₂ Using Nanoporous Reduced Graphene Oxide (RGO)/Cadmium Sulfide (CdS) as Catalyst on Porous Anodic Alumina (PAA)/Aluminum Support.

Solar conversion of CO₂, using a photocatalyst in the presence of water, has attained considerable attention due to added value of the process in terms of both reduction of an environmental pollutant and production of valuable synthetic chemicals. Room temperature fabrication of porous anodic alumina (PAA), for sufficiently low time, facilitates the synthesis of self-withstanding PAA with a middle layer of aluminum. Nanoporous reduced graphene oxide (RGO), deposited on the pore walls of PAA, with subsequent deposition of cadmium sulfide (CdS) as photocatalyst over it, and efficiently enhances the photocatalytic reduction of CO₂. Morphological, structural and optical characterizations of the catalyst are executed using field emission scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRD), electron dispersive X-spectroscopy (EDX) and UV-Vis absorption spectroscopy methods. Continuous photocatalytic reduction of CO₂ was carried out using flat sheet reactors and a compound parabola as the solar reflector. Semiconducting CdS nanorods, grown over PAA support with conducting RGO, show enhanced photocatalytic reduction of CO₂ to 153.8 mol/g/hr of CH₃OH with higher photocatalytic stability than CdS alone.