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 photo-catalytic 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 μmol/g catal. following 10 h of visible light illumination. The yield is much higher than those of TiO2 and physical absorbed CoPc/TiO2.