In this study, TiO2-based photocatalysts modified with Pt and Cu/CuOx were synthesized and studied in the photocatalytic reduction of CO2. 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 TiO2 at 700 °C and the use of Cu/CuOx instead of Pt allow one to design a highly efficient photocatalyst for CO2 transformation shifting the working range to the visible light (425 nm). Cu/CuOx/TiO2 (calcined at 700 °C) shows a rate of CH4 formation of 1.2 ± 0.1 µmol h-1 g-1 and an overall CO2 reduction rate of 11 ± 1 µmol h-1 g-1 (at 425 nm).
Keywords: CH4 production; CO2 reduction; TiO2; copper oxides; photocatalysis; platinum; ultraviolet light; visible light.