Catalytic performance of silver nanowires in plasmon-driven X-C bond cleavage studied by SERS

Plasmonic photocatalysis shows huge potential for efficient light energy harvesting by leveraging the unique and peculiar properties of plasmonic metallic nanostructures (usually Ag or Au) to drive light-induced chemical reactions. Metallic plasmonic nanoparticles (NPs) exhibit unique optical properties due to the possibility of exciting the collective oscillation of surface electrons, known as localized surface plasmon resonance (LSPR).This plasmonic behavior is strictly related to the chemical nature, size, and shape of the NPs; this, adjusting the plasmonic resonance, varying the size and shape of the NPs, can be very essential to expand the application scope of the NPs, including areas like sensing, light and energy capture, biomedicine and catalysis, in addition to enabling more extensive generation of excited carriers (hot electrons and holes) in NPs with tips and corners. This is because, while spherical nanoparticles exhibit plasmon resonance over a relatively narrow wavelength range, anisotropic nanoparticles offer more options for controlling the plasmonic resonance wavelength, from the visible to the mid-infrared, depending on the morphology and aspect ratio of the NPs. In the present work, the dehalogenation of the substituted aromatic thiols 4- bromobenzenethiol (4BBT), 4-chlorobenzenethiol (4CBT) and 4-fluorobenzenethiol (4FBT) was studied using SERS, which resulted in the formation of thiophenol (TP). The reaction as a function of the incident radiation power, using silver nanowires (AgNW) and bimetallic (Ag/Pdx%) nanowires as substrates were monitored by SERS. Cleavage of the Br-C and Cl-C bonds was observed in the presence of AgNW, with the trend Br-C > Cl-C. However, it was possible to observe the cleavage of F-C bond in the presence of Ag/Pdx% with different yields depending on the molar percentage of Pd.