Characterization, X-ray Absorption Spectroscopic Analysis and Photocatalytic Activity of Co/Zn Co-Doped TiO2 Nanoparticles Synthesized by One-Step Sonochemical Process

The Photocatalytic Conversion of Carbon Dioxide to Fuels Using Titanium Dioxide Nanosheets/Graphene Oxide Heterostructure as Photocatalyst

Carbon dioxide (CO₂) photoreduction to high-value products is a technique for dealing with CO₂ emissions. The method involves the molecular transformation of CO₂ to hydrocarbon and alcohol-type chemicals, such as methane and methanol, relying on a photocatalyst, such as titanium dioxide (TiO₂). In this research, TiO₂ nanosheets (TNS) were synthesized using a hydrothermal technique in the presence of a hydrofluoric acid (HF) soft template. The nanosheets were further composited with graphene oxide and doped with copper oxide in the hydrothermal process to create the copper-TiO₂ nanosheets/graphene oxide (CTNSG). The CTNSG exhibited outstanding photoactivity in converting CO₂ gas to methane and acetone. The production rate for methane and acetone was 12.09 and 0.75 µmol h^-1 g_cat^-1 at 100% relative humidity, providing a total carbon consumption of 71.70 µmol g_cat^-1. The photoactivity of CTNSG was attributed to the heterostructure interior of the two two-dimensional nanostructures, the copper-TiO₂ nanosheets and graphene oxide. The nanosheets-graphene oxide interfaces served as the n-p heterojunctions in holding active radicals for subsequent reactions. The heterostructure also directed the charge transfer, which promoted electron-hole separation in the photocatalyst.