Active Plasmonics with Polyaniline-Coated Gold Nanoparticles: A Facile Annealing and Electrochemical Approach

Noble metal nanostructures with real-time tunable plasmonic resonances have aroused wide research interest in the fields of materials science, physics, and chemistry. Among various engineering techniques for dynamic plasmonics, combining electrochromic polymers with plasmonic nanostructures is considered a significant strategy in constructing efficient dynamic plasmonic-based photonic devices. We demonstrate electrochemically depositing polyaniline (PANI) on gold nanoparticles (Au-NPs) to realize dynamic localized surface plasmon resonance (LSPR). To simplify the fabrication process, Au-NPs are obtained through thermal evaporation and the following annealing treatment. The dynamic plasmonic color switching is carried out through the electrochemically induced redox reaction of PANI. As a consequence, excellent switching performance on the plasmon resonance of Au-NPs is achieved through combining with electrochromic PANI. The PANI@Au-NP nanostructures show prominent reversibility over 50 switching cycles without distinct degradations, which is promising for a range of applications in optical devices, smart windows, and plasmonic chemical sensors.