Toward a comprehensive understanding of effect of cation distribution and M2+ constituent in spinel ferrite nanocrystals MFe2O4 (M = Co, Mn, and Ni) on the electrochemical response in sensitive detection of chloramphenicol

An Optimized MnO2-Ag Nanocomposite-Based Sensing Platform for Determination of 4-nitrophenol in Tomato Samples: Influences of Morphological Aspect of MnO2 Nanostructures and Synergic Effect on Electrochemical Kinetic Parameters and Analytical Performance

“…In addition, the linear relationships between the peak current intensity against the square root of the scan rate (ν 1/2 ) were found, revealing the reversible redox reaction of [Fe(CN) 6 ] 3−/4− probes occurring at the electrode-electrolyte interface was a diffusion controlled process. From that, the electrochemical active areas (A) of these electrodes were calculated by using the Randles-Ševčík equation as follows (25 °C): 11,34 This result was consistent with the results observed from physical characterizations when MnO 2 nanosheet-Ag possessed a unique nanocomposite structure with synergic effects coming from the uniform distribution of AgNPs on the MnO 2 nanosheet surfaces. In this case, MnO 2 nanosheets acted as an effective conductive matrix possessing ultrathin thickness, small diffusion ion length, good structural flexibility, and high active area as well as other unique physicochemical properties including better electrical conductivity, and chemical stability, while, the strong active AgNPs were decored effectively on this matrix.…”

“…6a′-6c′), confirming that the electrode reaction is an adsorption-controlled process nature rather than diffusion process. 43 According to that, the adsorption capacity of 4-NP (Г) on the modified electrode surfaces was also determined through the equation 11,42 (I p = n 2 F 2 AГν/4RT) at around 6.42 × 10 -11 , 7.56 × 10 -11 , and 8.22 × 10 -11 mol cm −2 for MnO 2 rods-Ag/SPE, MnO 2 wires-Ag/SPE, and MnO 2 sheets-Ag/SPE, respectively. Besides, the redox peak potential shift of 4-NP was positive according to a linear relationship with ln(ν), corresponding to the linear regression equations: Based on the Laviron equation 40,41,44 for the surface-controlled transfer model:…”

Electrochemical Kinetic Behaviors and Sensing Performance of Au@ZIF-8 and Ag@ZIF-8 Nanocomposites-Based Platforms Towards Ultrasensitive Detection of Chloramphenicol

“…Additionally, the electrochemical active area (A) was determined using the Randles-Sevcik equation at the room conditions (25 °C). [27][28][29][30] The equation is given by: 31 I p (μA) = 2.69 × 10 5 n 3/2 AD 1/2 ν 1/2 C; where n = 1 (the number of electrons transferred in redox reaction of Fe(CN) 6 3−/4 ), D = 6.5 × 10 -6 (diffusion coefficient-cm 2 s −1 ), C is bulk concentration of Fe(CN) 6 3−/4− . According to that, then calculated electrochemical active area (A) was approximately 0.146 cm 2 for the unmodified electrode (bare SPE) and 0.184, 0.186, and 0.186 cm 2 for the modified electrodes (ZIF-8/SPE, Ag@ZIF-8/SPE, and Au@ZIF-8/ SPE), respectively.…”