Exploring CuxO-doped TiO2 modified with carbon nanotubes for CO2 photoreduction in a 2D-flow reactor

Abstract

Different photocatalysts based on the combination of TiO2 and CuxO have been prepared by simple and reproducible procedures. The synthesized systems have been applied in the photoreduction of CO2 to yield CH4 inside a 2-dimensional flow reactor in which the gas stream was passed over a thin layer of the catalyst under UV irradiation. Analysis of the photocatalysts reveals that the oxidation state of Cu changes throughout the reaction, thus modifying the physicochemical properties of the catalysts. The combination of core-level and valence-band level spectroscopies allowed us to draw the band diagram for the best catalyst, showing a Z-scheme structure. The reactor design and the photocatalyst developed can produce CH4 at a very high production rate with extreme efficiency. After further optimization through suppression of side reactions, we obtained one of the highest values reported for any type of reactor or catalytic system with a CH4 formation rate over 100 μmolCH4·gcat−1 h−1 using low power LED lighting.