Tetraphenylporphyrin Decorated Bi2MoO6 Nanocomposite: Its Twin Affinity of Oxygen Reduction Reaction and Electrochemical Detection of 4-Nitrophenol.

Abstract

A selective electrode for oxygen reduction reaction (ORR) and electrocatalytic reduction of 4-nitrophenol (p-NP) was fabricated on a glassy carbon electrode using organic-inorganic Bi2MoO6/H2TPP nanocomposites with different weight percentages of tetraphenylporphyrin, synthesized by the solvothermal process. Materials thus synthesized were characterized through UV-Vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) analysis. The electrocatalytic performance of the modified electrode toward ORR in the 0.1 M KOH solution, the onset potential Eonset (0.942 V), E1/2 (0.704 V) vs RHE, Jd (-5.545 mA cm-2), and n = 4 physicochemical parameters were well appreciable. It exhibits good catalytic activity toward ORR through a four-electron pathway with excellent stability and high active site density, and thus, the in situ Porphy-decorated metal oxide system facilitates the electron transport process. High selectivity and efficacy for the oxygen reduction reaction (ORR) are a significant measure for several energy-converting applications. The decorated electrode, glassy carbon electrode (GCE)/Bi2MoO6/3 wt % Porphy, serves as an electrochemical sensor that exhibited good sensitivity (0.4683 μAμM-1 cm-2), good reproducibility, a low detection limit (0.0940 μM), and long-term stability in the aqueous phase without any appreciable effect in the presence of some common organic and inorganic interferences for the detection of p-NP in a linear concentration range of 0.5-350 μM. Therefore, the material performs as an effective electrode for both the ORR and the electrocatalytic reduction of p-NP with real matrix samples at room conditions.