Photo-Assisted CO/CO2 Methanation over Ni/TiO2 Catalyst: Experiment and Density Functional Theory Calculation

Supported Ni-based catalysts have been widely used in CO and CO2 methanation processes. However, the catalytic activity of presently available Ni-supported catalysts remains deficient at the low temperatures required to avoid sintering and carbon deposition. The present work addresses these issues by fabricating TiO2-nanoparticle-supported Ni (Ni/TiO2) photothermal catalysts achieve a CO and CO2 conversion of 94 % and 76 %, respectively, under Xe lamp irradiation at 300 degrees C than those obtained under strictly thermal catalysis conditions. Diffuse reflectance infrared Fourier-transform spectroscopy results conducted in situ with and without light irradiation demonstrate that photoinduced charge carriers on the surfaces of the Ni/TiO2 nanoparticles enhance the formation of intermediate species in the CO methanation process and the formation of CO2 delta- species conducive to CO2 activation in the CO2 methanation process. Moreover, density functional theory calculations with explicitly included charge carriers further demonstrate that electrons are transferred from Ti to Ni in the Ni/TiO2 catalyst under light irradiation. This research advances understanding of CO/CO2 low temperature methanation activity by light irradiation and provides a practical way to address the existing problem for Ni-based catalysts.

Automated summary

In this study, Ni catalysts supported by TiO2 nanoparticles were fabricated and showed significantly improved methane conversion of CO and CO2 at low temperatures under light irradiation. The photoinduced charge carriers on the surfaces of the Ni/TiO2 nanoparticles enhanced the formation of intermediate species in the methanation process, as well as the formation of CO2 delta- species conducive to CO2 activation in the CO2 methanation process.