Plasmon-enhanced oxygen reduction reaction using silver nanoparticle-decorated N-doped carbon nanotubes

Abstract

The oxygen reduction reaction (ORR) generally limits the efficacy of hydrogen fuel cells, due to its sluggish kinetics. Here, we present an effective plasmon-enhanced catalyst for the ORR, based on silver nanoparticle-decorated carbonized polypyrrole nanotubes (Ag-cPNTs). Silver nanoparticles (AgNPs) were incorporated onto the surface of carbonized polypyrrole nanotubes (cPNTs) using a straightforward and reproducible method without the need for wet synthesis. The cPNTs serve as redox-active supports with a high surface area, while AgNPs efficiently absorb and convert light energy into plasmonic excitation, facilitating oxygen activation. The successful introduction of AgNPs and their uniform morphology and size distribution were observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The analysis of the chemical composition, performed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), confirmed the formation of AgNPs. Having been thoroughly characterized, the performance of the Ag-cPNTs was tested in the ORR under both illumination and dark conditions. LED illumination (455 nm central wavelength) of the prepared plasmon-active catalyst results in an increase of current density and LSV curve shift of potential to more positive values. Overall, a high surface area, porous interconnected structure, and photo-enhanced catalytic activity demonstrated high potential of the prepared composite as a novel catalyst for fuel cell applications.