Green synthesis of plasmonic Ag nanoparticles anchored TiO2 nanorod arrays using cold plasma for visible-light-driven photocatalytic reduction of CO2

A novel method employing atmospheric pressure dielectric barrier discharge (DBD) cold plasma has been developed to reduce supported Ag nanoparticles (AgNPs) without the use of any environmentally and biologically hazardous reducing chemicals. X-ray photoelectron spectroscopy and UV-vis absorption spectra show that the supported metal ions are completely reduced to the metallic state within a short time (30 s). The morphology and dispersion of the AgNPs were characterized by scanning electron and transmission electron microscopy. The results show that the AgNPs are homogeneously distributed with an average particle size of less than 6 nm, which brings the effect of localized surface plasmon resonance (LSPR). The AgNPs-modified samples show remarkable improvement for reducing CO2 to CO and CH4 under visible light compared to pristine TiO2. The formation mechanism of the method for the reduction and stabilization of AgNPs is also discussed.