Plasmonic Ag@TiO₂ Core–Shell Nanoparticles\nfor Enhanced CO₂ Photoconversion to CH₄

Abstract

Ag@TiO₂ nanoparticles (NPs) with Ag metal cores and\nTiO₂ semiconductor shells were prepared with a hydrothermal\nmethod and their structure was characterized by scanning electron\nmicroscopy, transmission electron microscopy, and X-ray diffraction.\nThe core–shell Ag@TiO₂ NPs were deposited on a glass\nplate and employed as photocatalysts for CO₂ conversion\nby irradiation of solar simulator (AM1.5) under CO₂ atmosphere.\nSelective CH₄ evolution by CO₂ photoconversion\nwas attained with the core–shell Ag@TiO₂ NP photocatalyst.\nThe CH₄ evolution rate normalized by specific surface areas\nwas 10 times higher than those of reference TiO₂ NPs and\nconventional TiO₂ NPs with accompanying Ag deposits. The\nrole of the Ag core was also demonstrated in photodecomposition of\na dye by the core–shell Ag@TiO₂ NPs. These results\nsuggested that the high photocatalytic activity of the core–shell\nAg@TiO₂ NPs was archived due to bandgap improvement of\nthe TiO₂ shell and increase of photon flux to the TiO₂ shell by the plasmonic Ag core.