Synthesis of hierarchical Au/TiO2 plasmonic nanocomposite for enhancement of photocatalytic reduction of CO2 to CO

The increasing worldwide consumption of fossil fuels has accelerated the global energy consumption rate and led to overproduction of the carbon dioxide, resulting in global climate change and energy crisis. Semiconductor-based photocatalytic reduction of CO2 with H2O to renewable hydrocarbon fuels by solar energy has attracted enormously attention in recent years. Among the semiconductor photocatalysts, Titanium dioxide (TiO2) has been extensively used in the photocatalytic fields including water splitting, degradation of organic contaminants, and CO2 reduction due to its cheap, non-toxic, and light stability. Herein, High specific surface area three-dimensional pine tree-like hierarchical TiO2 nanotube array films loaded with Au nanoparticles were successfully prepared by one-step hydrothermal reaction combining with simple and feasible thermal evaporation system. These photocatalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), the elemental chemical status and compositions were analyzed with X-ray photoelectron spectroscopy (XPS). The result of the photo-reduction of CO2 shows that the composite Au/TiO2-branched nanotube arrays shows efficiently reduce CO2 to CO under UV visible light irradiation, which is about 2.4 times higher than that of pure TiO2 nanotube arrays. The Au/TiO2 nanocomposite photocatalyst is stable with the prolonged time and reaction duration. The enhancement of photocatalytic reduction of CO2 is attributed to the boost of plasmonic effect enhancement carrier generation and separation, higher specific surface area, faster charge transport, and superior light-harvesting efficiency for efficient charge collection. The work provides a cost-effective, flexible and clean method to develop high-performance photocatalytic reduction of CO2 to renewable hydrocarbon fuels by solar energy.