Electrochimica Acta, Vol.306, 466-476, 2019
Wall thickness-tunable AgNPs-NCNTs for hydrogen peroxide sensing and oxygen reduction reaction
The nitrogen-rich carbon nanotubes doped with well-dispersed fine silver nanoparticles (AgNPs-NCNTs) were fabricated by carbonization of the silver-polydopamine (AgNPs-PDA) multilayers. The wall thickness of the nanotube is tunable by varying the numbers of the layer-by-layer alternate deposition of Ag and PDA on electrospun polystyrene (PS) fibers. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) demonstrate the tunable tubular structure by various AgNPs-PDA layers and the uniform distribution of fine silver nanoparticles with the size of about 6 nm in the nanotube. The composition of the nanocomposites was characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) demonstrate that the electrochemical properties of AgNPs-NCNTs depend on the numbers of AgNPs-PDA layers. The composite material shows excellent electrocatalytic activity to H2O2 reduction, with a low limit of detection (LOD) of 0.03 mu M(S/N >= 3) and a sensitivity of 1004.9 mu A mM(-1) cm(-2). Meanwhile, the AgNPs-NCNTs present a high catalytic activity to O-2 reduction reaction with near 4-electron transfer process. The related catalysis mechanisms were proposed and validated by rotating disk electrode and dissolved oxygen analysis. This catalyst shows high stability for oxygen reduction over 500 cycles. (c) 2019 Elsevier Ltd. All rights reserved.