Photocatalytic CO2 conversion over Au/TiO2 nanostructures for dynamic production of clean fuels in a monolith photoreactor

Abstract

Global economic development intensifies the consumption of fossil fuels which results in increase of carbon dioxide (CO2) concentration in the atmosphere. The technologies for carbon capture and utilization to produce cleaner fuels are of great significance. However, phototechnology provides one perspective for economical CO2 conversion to cleaner fuels. In this study, CO2 conversion with H2 to selective fuels over Au/TiO2 nanostructures using environment friendly continuous monolith photoreactor has been investigated. Crystalline nanoparticles of anatase TiO2 were obtained in the Au-doped TiO2 samples. The Au deposited over TiO2 in metal state produced plasmonic resonance. CO2 was efficiently converted to CO as the main product over Au/TiO2 with a maximum yield rate of 4144 µmol g-catal.−1 h−1, 345 fold-higher than using un-doped TiO2 catalyst. The significantly enhanced photoactivity of Au/TiO2 catalyst was due to hindered charges recombination rate and Au metallic-interband transition. The photon energy in the UV range was high enough to excite the d-band electronic transition in the Au to produce CO, CH4, and C2H6. The quantum efficiency over Au/TiO2 catalyst for CO was considerably improved in the continuous monolith photoreactor. At higher space velocity, the yield rates of CO gradually reduced, but the initial rates of hydrocarbon yields increased. The stability of the recycled Au/TiO2 catalyst was sustained in cyclic runs. Thus, Au-doped TiO2 supported over monolith channels is promising for enhanced CO2 photoreduction to high energy products. This provides pathway that phototechnology to be explored further for cleaner and economical fuels production.