New Catalysts for the Photocatalytic Reduction of Carbon Dioxide to C1 Organic Compounds

摘要

Photocatalytic reduction of carbon dioxide (CO2) has recently been identified as one of the five notable research areas in catalysis because it simultaneously reduces carbon emissions while storing clean, “green” solar energy in organic compounds. The development of efficient photocatalysts that take advantage of solar radiation is therefore an important area of research. Titanium dioxide (TiO2) is a commonly-used photocatalyst for this reaction, but it requires ultraviolet (UV) radiation to excite its electrons. Carbon-doping (C-doping) has been shown to reduce the intensity of energy required, thus allowing the photocatalyst to take advantage of the visible light spectrum. Copper (Cu), added as separated particles and not introduced into the catalyst structure, has also been reported to enhance the photocatalytic effect. Here, a comparison of the efficiency of CO2 reduction by the following photocatalysts is reported: commercial TiO2, commercial TiO2-Cu, C-doped TiO2, C-doped TiO2-Cu, undoped TiO2, and undoped TiO2-Cu. Photocatalytic reactions were conducted in a single neck flask which was irradiated by a Xenon lamp. The aqueous product was analyzed for total organic carbon (TOC) content and also by using a mass spectrometer. Gas analysis was not conducted in the present study. Results suggest that among the photocatalysts studied here, commercial TiO2 is the most effective in producing TOC. However, comparing only the samples synthesized from titanium sulfate (TiOSO4) in our laboratory, C-doped TiO2 is more effective than undoped TiO2. The addition of copper was found to have an inconclusive effect on the production of TOC.