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 Bi 2 MoO 6 /H 2 TPP 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), highresolution 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 E onset (0.942 V), E 1/2 (0.704 V) vs RHE, J d (−5.545 mA cm −2 ), and n = 4 physicochemical parameters were well appreciable. It exhibits good catalytic activity toward ORR through a fourelectron 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)/Bi 2 MoO 6 /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.

β-Bi2O3–Bi2WO6 Nanocomposite Ornated with meso-Tetraphenylporphyrin: Interfacial Electrochemistry and Photoresponsive Detection of Nanomolar Hexavalent Cr

“…However, the absorption peak at 1744 cm –1 increased with the increasing amount of H 2 TPP, indicating an increase in the N-containing π-conjugated organic species on the nanocomposites thus prepared . The peaks at 2854 and 2918 cm –1 are responsible for the symmetric and asymmetric stretching vibrations of the −CH 2 group. , The absorption bands at 963 and 798 cm –1 appeared due to the in-plane and out-of-plane δ N–H of H 2 TPP . This further confirmed the effective surface modification of β-Bi 2 O 3 –Bi 2 WO 6 by H 2 TPP, wherein H 2 TPP is firmly attached to the surface through electrostatic interactions.…”

“…Figure a indicates that all of the nanocomposites have strong absorption in the visible region. A significant Soret band at 438.57 nm due to the π–π* transition of the macrocyclic ring was observed , in the diffuse reflectance spectroscopy (DRS) spectrum of H 2 TPP, as shown in Figure S6b. The red-shifting of the Soret band of H 2 TPP in β-Bi 2 O 3 –Bi 2 WO 6 /5 wt % H 2 TPP at 526.28 nm indicates increased absorption in the solar region and the quick generation of photogenerated electron and hole pairs.…”

“…The electro-/photoelectrochemical performance of H 2 TPP-ornated β-Bi 2 O 3 –Bi 2 WO 6 nanomaterials for Cr 6+ sensing using electrochemical impedance spectroscopy (EIS), current–time curve ( i – t ) analysis, and cyclic voltammetry (CV) was systematically examined for the first time. The adsorption of chromium ions on the active site of H 2 TPP in β-Bi 2 O 3 –Bi 2 WO 6 /H 2 TPP facilitates the electro- or photoelectrochemical reduction of Cr 6+ with a low detection limit, high and quick sensitivity, and persisting stability by increasing the fluorescence lifetime of the photocarrier and decreasing the charge recombination rate of the photogenerated electron–hole pair, , making our sample a promising sensor for hexavalent chromium. Thus, H 2 TPP is a reliable electronic match between the material surface and hexavalent chromium.…”

Oyster Pearl-Shaped Ternary Iron Chalcogenide, FeSe0.5Te0.5, Films on FTO through Electrochemical Growth from the Exchange of Chalcogens Boosted the Enzyme-Free Urea-Sensing Ability toward Real Analytes

“…CV plots of FTO/FeSe and FTO/FeTe in the non-faradic region and capacitive current plots are shown in Figure S5a–c′ in the Supporting Information. The ECSA and R f values of the materials were determined by the following equations ECSA = C dl C normals R normalf = ECSA / GSA where C s is the ideal specific capacitance value of the same material under identical conditions of electrolyte per unit area. The geometrical surface area (GSA) is considered to be 1 cm 2 of the FeSeTe-modified FTO glass for the calculation of the roughness factor.…”

“…= R f ECSA/GSA (10) where C s is the ideal specific capacitance value 52 of the same material under identical conditions of electrolyte per unit area. The geometrical surface area (GSA) is considered to be 1 cm 2 of the FeSeTe-modified FTO glass for the calculation of the roughness factor.…”