Optimal design and preparation of titania-supported CoPc using sol-gel for the photo-reduction of CO2

CoPc-loading titania (CoPc/TiO2) was synthesized by an improved sol-gel method using a homogeneous hydrolysis technique. In order to increase C1 products in the photo-reduction of CO2, preparation conditions of photo-catalysts were optimized using a four-level OAD16 (4(5)) matrix in which molar ratio of reacting species, solvent, pH, mass ratio of CoPc to TiO2, and calcining temperature were chosen as main parameters. The results obtained by orthogonal array design (OAD) method indicate that calcining temperature was the most important parameter influencing the photo-reduction of CO2. Under optimal experimental conditions the total yield of reduction products of CO2 in NaOH aqueous solutions was 406.65 mu mol/g-catal. The grain size of CoPc/TiO2 was uniform with an average diameter of approximately 11 nm. In addition, the catalyst was characterized by X-ray powder diffraction, scanning electron microscopy. UV-vis DRS, BET and FT-IR spectroscopy. CoPc/TiO2 catalyst synthesized by sol-gel exhibited relatively high photochemical activity for the reduction of CO2 compared with TiO2 prepared by sol-gel method. (C) 2009 Elsevier B.V. All rights reserved.