Visible Light Photoreduction of CO₂ Using CdSe/Pt/TiO₂ Heterostructured Catalysts

Abstract

A series of CdSe quantum dot (QD)-sensitized TiO₂ heterostructures have been synthesized, characterized, and tested for the photocatalytic reduction of CO₂ in the presence of H₂O. Our results show that these heterostructured materials are capable of catalyzing the photoreduction of CO₂ using visible light illumination (λ > 420 nm) only. The effect of removing surfactant caps from the CdSe QDs by annealing and using a hydrazine chemical treatment have also been investigated. The photocatalytic reduction process is followed using infrared spectroscopy to probe the gas-phase reactants and gas chromatography to detect the products. Gas chromatographic analysis shows that the primary reaction product is CH₄, with CH₃OH, H₂, and CO observed as secondary products. Typical yields of the gas-phase products after visible light illumination (λ > 420 nm) were 48 ppm g⁻¹ h⁻¹ of CH₄, 3.3 ppm g⁻¹ h⁻¹ of CH₃OH (vapor), and trace amounts of CO and H₂