Multilayer Films of Cerium Doped TiO₂ for Photocatalytic Reduction of CO₂

Abstract

Carbon dioxide, generated largely from combustion of fossil fuels, is one the most discussed gases of present time. It is one of the major greenhouse gases and also the most abundant and not utilized carbon source. This work is focused on photocatalytic reduction of carbon dioxide to not only reduce its emissions, but also to convert it into more useful products like methane, methanol, formic acid and others. The photocatalytic reduction of CO₂ was carried out in the gas phase in the presence of cerium doped TiO₂ photocatalysts in the form of multilayer films. All the prepared photocatalysts were characterized by available methods; the products of the reaction were methane, carbon monoxide and hydrogen, which originated from the photocatalytic water splitting. The photocatalysts with higher amount of cerium (15 and 25 wt.%) were the most active. Both these samples were amorphous and showed more than twice as high photoactivity compared to multilayer film of TiO₂. Such a high photocatalytic activity of amorphous samples is probably connected to lower recombination rate of electrons and holes due to amorphous TiO₂ acting as hole scavenger and the cerium in ion form (Ce⁴⁺) acting as electron scavenger.