Effect of the Morphology of TiO2/Ti Electrodes on Photoactivity in the Electrochemical Reduction of Carbon Dioxide

Abstract

UDC 544.526.5, 544.653.3 M. L. Ovcharov, A. M. Mishura, V. V. Shvalagin, and V. M . GranchakA study was carried out on the photoelectrochemical reduction of CO 2 using TiO 2 /Ti photoelectrodes, whose activity increases in going from samples obtained by dip-coating method to films formed by electrochemical anodization of titanium and further increases in going from disordered structures (spongy structure) to ordered nanotube structure. The introduction of electron donors into the anode chamber of the photoelectrochemical cell considerably enhances the photoactivity of the system. In the series of electron donors studied, this photoactivity increases in the The photoelectrochemical reduction of CO 2 is a promising method for the conversion of solar energy into chemical energy, whose practical realization would permit us not only to obtain electrical energy and produce organic products from carbon dioxide [1] but also facilitate the use of organic wastes as secondary energy sources [2]. Intensive research is now underway on the photoelectrochemical production of organic compounds from carbon dioxide using various semiconductor electrodes [3]. However, there has been hardly any systematic investigation of the role of the morphology of semiconductor photoelectrode in the photoelectrochemical reduction of CO 2 even though this factor is known to have a significant effect on the activity of such electrodes [4].In the present work, we investigated the relationship between the morphology of the surface of TiO 2 /Ti electrodes, obtained both by electrochemical anodization under various conditions and by the sol-gel method, and the activity of these materials as anodes in the photoelectrochemical reduction of CO 2 . EXPERIMENTALMesoporous films of titanium dioxide (meso-TiO 2 /Ti) were obtained by the sol-gel method upon the hydrolysis of titanium tetraisopropoxide obtained from Aldrich in the presence of BASF Pluronic P123 triblock-copolymer of ethylene oxide and propylene as the template [5]. The films were deposited onto a titanium plate by dip-coating method with deposition rate 1.5 mm/s. After deposition, the films were left in the air for 2 h and then roasted in a muffle furnace at 400°C for 2 h. In the experiments, we used six-layer coatings obtained by consecutive film deposition after drying of each layer in the air. 2180040-5760/14/5004-0218