An
efficient and simple way has been described to prepare gold
and silver bimetallic alloy nanoparticles (Au-AgNPs) in an organic
framework with a metal-free core. The growth of alloy Au-AgNPs was
monitored by UV–visible spectroscopy (UV–vis) and confirmed
using various spectral, microscopy, and electrochemical techniques.
The field-emission scanning electron microscopy (FE-SEM) and transmission
electron microscopy (TEM) results revealed that the covalent organic
framework (COF) had a uniform flake-like morphology, and the alloy-based
Au-AgNPs had a flower-like structure. The results of X-ray photoelectron
spectroscopy (XPS) and X-ray diffraction (XRD) indicated that Au-AgNPs
are metallic in nature and highly crystalline. The surface of a glassy
carbon electrode (GCE) was then modified with Au-AgNPs-COF, which
was subsequently employed for enzyme-free electrochemical reduction
of H2O2. The electrocatalytic cyclic voltammetry
performance of the different modified electrodes was in the following
order: COF (−14.82 μA) < AgNPs-COF (−26.95
μA) < AuNPs-COF (−31.78 μA) < Au-AgNPs-COF
(−46.15 μA). The Au-AgNPs-COF/GCE displayed an excellent
electrocatalytic activity toward reduction of H2O2, over a dynamic range of 2.0 nM–1.0 mM with a limit of detection
(LOD) of 0.44 nM (S/N = 3). Furthermore, the present sensor showed
appreciable selectivity, stability, and reproducibility against the
reduction of H2O2. Practicality was demonstrated
in fetal bovine serum (FBS), cat blood serum (CBS), and living cells
(RAW 264.7).
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