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The fabrication of nanocomposites
is essential because a multiphase interface delivers highly sensitive
and selective method for the individual and simultaneous electrochemical
determination of drugs. Herein, we introduce an electrochemical sensor
using Pt/CeO2@Cu2O nanocomposites for simultaneous
detection of dopamine (DA) and paracetamol (PA), which were synthesized
using a low temperature clean aqueous phase additives-free method
with Cu2O as sacrificial template. We investigated the
electrochemical behavior of the various modified electrodes by cyclic
voltammetry (CV) and differential pulse voltammetry (DPV), in which
Pt/CeO2@Cu2O proved to be highly sensitive and
selective toward individual and simultaneous detection of DA and PA.
Sensitive electrooxidation peak potential at 160 mV and 380 mV from
the DPV technique was observed for DA and PA, respectively. Both DA
and PA exhibit linear response over the range of 0.5 μM to 100
μM. The stability, reproducibility, and repeatability of the
Pt/CeO2@Cu2O were also inspected. The lower
detection limits of 0.079 μM and 0.091 μM were recorded
for DA and PA, respectively. The practical applicability of the Pt/CeO2@Cu2O–carbon paste electrode (CPE) is toward
the simultaneous detection of DA and PA in drugs, as well as in spiked
human serum and urine samples.
Development of highly active and stable low-cost Pt-free catalysts for ethanol electrooxidation (EOR) in alkaline medium has drawn a lot of attention in recent years. Palladium-based catalysts are on the forefront of this research. Pd 2 Ge, previously developed by our group, is a highly active and stable catalyst for EOR because of its ordered structure and the presence of Ge. In this work, we used it as a platform to further enhance its efficiency by Ni substitution (Pd 2−x Ni x Ge), which shifts the d-band center of the catalysts toward the Fermi level with the increasing binding energy toward the adsorbate. Stronger interaction between the Ni, Pd, and Ge atoms leads to stronger adsorption of −OH intermediates (−436 kJ/mol) and weaker adsorption of −CH 3 CO (−220 kJ/mol). As a result, this catalyst exhibits 3.8 times higher mass activity and 70 mV lower onset potential than pristine Pd 2 Ge for EOR in alkaline media.
This work reports a graphene-based nonenzymatic electrochemical sensing platform for the detection of dopamine (DA), uric acid (UA), and ascorbic acid (AA). Graphene oxide, synthesized by modified Hummers method, was thermally reduced in an induction furnace at 200 °C in an Ar-H2 atmosphere to obtain thermally reduced graphene oxide (tRGO). Nanocomposites of tRGO-TiO2 were obtained by a hydrothermal method, and were characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray diffraction (XRD). FTIR spectra showed Ti-O-C peaks, indicating covalent linkage between the TiO2 nanoparticles and the reduced graphene oxide sheets. Glassy carbon electrode (GCE) was modified with the nanocomposite (tRGO-TiO2-GCE), and the modified electrode could detect dopamine (DA: 1 to 1000 µM), uric acid (UA: 1 to 900 µM), and ascorbic acid (AA: 10 to 1000 µM) in each other's presence over wide ranges, with adequate separation in peak potentials. Differential pulse voltammetry experiments yielded linear responses with sensitivities of 133.18, 33.96, and 155.59 µA mM(-1) cm(-2) for DA, UA, and AA, respectively.
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