Plasmon-enhanced catalysis of photo-induced charge transfer from TCNQF4− to TCNQF42−

Abstract

Ag₂–TCNQF₄ (TCNQF₄ = 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane) was synthesized for the first time via a photo-induced charge transfer of the precursor of semiconductor Ag–TCNQF₄ using Au nanoparticles (AuNPs) as a catalyst. We first prepared the one-dimensional Ag–TCNQF₄ crystal wires on a solid-supported substrate via a solution process. Then, Ag–TCNQF₄ was reacted with KAuCl₄via the galvanic replacement reaction to form a metal–semiconductor complex, AuNPs decorated Ag–TCNQF₄ (AuNPs@Ag–TCNQF₄). The resulting Ag–TCNQF₄ crystal wires and AuNPs@Ag–TCNQF₄ complex were characterized by scanning electron microscopy (SEM), X-ray diffraction, ultraviolet-visible (UV-vis) and X-ray photoelectron spectroscopies. Under the plasmon-enhanced catalysis of AuNPs, a laser-induced charge transfer process occurred on Ag–TCNQF₄, altering it to Ag₂–TCNQF₄. Time-resolved in situ Raman spectra were recorded to monitor the photo-induced charge transfer process. The Raman data show that this photo-induced charge transfer process is laser wavelength-dependant, power-dependant and irradiation time-dependant. It is also affected by the loading of AuNPs. The SEM images, UV-vis and infrared spectra of the AuNPs@Ag–TCNQF₄ before and after laser irradiation further prove that the charge transfer product is Ag₂–TCNQF₄. The mechanism of the plasmon-enhanced catalysis of photo-induced charge transfer from TCNQF₄⁻ to TCNQF₄²⁻ is suggested, which provides a good model to study the charge transfer process in metal–semiconductor systems. In addition, this material has significance for applications in memory storage and photoelectric devices.