Photo-catalytic reduction of carbon dioxide with in-situ synthesized CoPc/TiO 2 under visible light irradiation

Abstract

CO 2 is photo-catalytically reduced to produce formic acid, methanol, formaldehyde in an aqueous solution using visible light irradiation and in-situ synthesized CoPc/TiO 2. CoPc/TiO 2 nano-composite is in-situ synthesized through the annulations of 1,2-dicyanobenzene on the surface of TiO 2 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 TiO 2 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 TiO 2, 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/TiO 2 out performed physical absorbed CoPc/TiO 2. The total organic carbon (TOC) yield of 0.7 wt.% in-situ CoPc/TiO 2 is 1714.9 μmol/g catal. following 10 h of visible light illumination. The yield is much higher than those of TiO 2 and physical absorbed CoPc/TiO 2.