Photo-catalytic reduction of carbon dioxide with in-situ synthesized CoPc/TiO2 under visible light irradiation

CO2 is photo-catalytically reduced to produce formic acid, methanol, formaldehyde in an aqueous solution using visible light irradiation and in-situ synthesized CoPc/TiO2, CoPc/TiO2 nano-composite is in-situ synthesized through the annulations of 1,2-dicyanobenzene on the surface of TiO2 with Co(II) as template. The prepared catalysts are characterized by means of XRD, DTA-TG, UV-vis and FT-IR methods. The photo-catalytic activity of these catalysts under visible light is discussed. The experimental results indicate that cobalt-phthalocyanine (CoPc) and TiO2 are indeed synthesized by the in-situ method. Under the visible light irradiation, CoPc molecules are excited first and the excited electrons are injected into the conduction band of TiO2, then the separation of electron-hole pairs is increased so that the photocatalytic efficiency is increased. The results show that the in-situ CoPc/TiO2 out performed physical absorbed CoPc/TiO2. The total organic carbon (TOC) yield of 0.7 wt% in-situ CoPc/TiO2 is 1714 9 mu mol/g catal. following 10 h of visible light illumination. The yield is much higher than those of TiO2 and physical absorbed CoPc/TiO2. (C) 2009 Elsevier Ltd. All rights reserved.