Activation of Au-Ag Plasmonic Bimetallic Nanocatalysts with Cold Plasma: The Role of Loading Sequence of Plasmonic Metals and Discharge Atmosphere

作者：Zhu, Bin; Li, Xue; Deng, Xiao-Qing^*; Wang, Yan-Qun^*; Lu, Li-Lin

来源：Plasma Chemistry and Plasma Processing, 2022, 42(3): 671-687.

DOI：10.1007/s11090-022-10231-9

• Plasma treatment
• Photocatalysis
• Au-Ag nanocatalyst
• LSPR

The activation of Au-Ag plasmonic bimetallic nanocatalyst can make the nanocatalyst exhibit superior visible-light (VL) photocatalytic activity. An efficient activation of Au-Ag nanocatalyst by cold plasma requires the restructuring of Au and Ag species over catalyst surface to form Au-Ag alloy nanoparticles while suppressing agglomeration of the nanoparticles. We here report that the loading sequence of Au and Ag components on titanium dioxide (TiO2) support during catalyst preparation and discharge atmosphere play important roles in the plasma activation. Preparation of AuAg/TiO2 nanocatalyst by depositing Ag and Au in sequence could avoid the undesired loss of Ag component, and ensure an effective restructuring of Au and Ag species in O-2 plasma activation. Compared with the reductive (H-2) and inert (Ar and N-2) plasmas, discharge in oxidative O-2 establishes Coulomb field with the negatively charged species over catalyst surface and enable the restructuring and intimate interaction of Au and Ag species. The catalyst characterization and density functional theory calculations suggest that O-2 plasma endows AuAg/TiO2 nanocatalyst with large numbers of Au-Ag alloy nanoparticles, small size of plasmonic nanoparticles, high density of coordinatively unsaturated sites, and high content of surface oxygen species in the activation, which facilitates the adsorption and activation of O-2, and thus CO oxidation reaction under VL irradiation.