Photocatalytic Reduction of Carbon Dioxide to Methanol: Carbonaceous Materials, Kinetics, Industrial Feasibility, and Future Directions (original) (raw)

Carbon dioxide (CO 2) photoreduction by gaseous water over silica-pillared lamellar niobic acid, viz. HNb 3 O 8 , was studied in this work. The physicochemical characteristics of samples were examined by techniques such as XRD, FT-IR, SEM, TEM, and UV−visible diffuse reflectance spectroscopy. Aspects that influence CO 2 photoreduction, such as the layered structure, the protonic acidity, silica pillaring, and cocatalyst loading, were investigated in detail. Pt loading obvious promoted the activity for CO 2 photoreduction to methane. The loading of Pt also promoted the formation of methane from catalyst associated carbon residues, although this contributes insignificantly to the overall amount of methane produced. The layered structure and the protonic acidity of the lamellar niobic acid have significant influences on CO 2 photoreduction by water in gas phase. With layered structure, expanded interlayer distance, and stronger intercalation ability to water molecules, the silica pillared niobic acid showed much higher activity than the nonpillared niobic acid, Nb 2 O 5 , and TiO 2. Because of the unique adsorption ability to water molecules through hydrogen bonding, the activity of silica pillared HNb 3 O 8 increased more remarkably with elevated water content than the mostly investigated TiO 2 photocatalyst.