Broadening the Action Spectrum of TiO 2 -Based Photocatalysts to Visible Region by Substituting Platinum with Copper.

In this study, TiO 2 -based photocatalysts modified with Pt and Cu/CuO x were synthesized and studied in the photocatalytic reduction of CO 2 . The morphology and chemical states of synthesized photocatalysts were studied using UV-Vis diffuse reflectance spectroscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. A series of light-emitting diodes (LEDs) with maximum intensity in the range of 365-450 nm was used to determine the action spectrum of photocatalysts. It is shown for, the first time, that the pre-calcination of TiO 2 at 700 °C and the use of Cu/CuO x instead of Pt allow one to design a highly efficient photocatalyst for CO 2 transformation shifting the working range to the visible light (425 nm). Cu/CuO x /TiO 2 (calcined at 700 °C) shows a rate of CH 4 formation of 1.2 ± 0.1 µmol h -1 g -1 and an overall CO 2 reduction rate of 11 ± 1 µmol h -1 g -1 (at 425 nm).