Voltammetric sensor based on glassy carbon electrode modified with hierarchical porous carbon, silver sulfide nanoparticles and fullerene for electrochemical monitoring of nitrite in food samples

Square-Wave Voltammetric Detection of Zn(II) and Cd(II) with a Graphite/Carbon Paste Electrode Decorated with 2-Hydroxy-1,4-naphthoquinone

“…The linear equations obtained from the data are as follows: For Zn ( II ) : Log ( I pa ) = prefix− 0.086 + 0.586 Log ( υ ) goodbreak0em1em⁣ ( r 2 = 0.9874 ) For Cd ( II ) : Log ( I pa ) = prefix− 0.148 + 0.414 Log ( υ ) goodbreak0em1em⁣ ( r 2 = 0.9928 ) Furthermore, the slope values of approximately 0.586 for Zn(II) and 0.414 for Cd(II) indicate that the process corresponds to a coupled mechanism diffusion–adsorption control. A slope value close to 0.5 suggests that the rate-limiting step involves both diffusion and adsorption processes. , On the basis of these results, the reaction process of Zn(II) and Cd(II) metals is considered irreversible. To determine the number of transferred electrons during the oxidation processes, the relationship between E pa (peak potential) and ln(υ) (scan rate) is analyzed using Figure E.…”

“…To determine the number of transferred electrons during the oxidation processes, the relationship between E pa (peak potential) and ln(υ) (scan rate) is analyzed using Figure E. The linear equations obtained are presented as follows: For Zn ( II ) : E pa = prefix− 0.599 + 0.085 ln ( υ ) goodbreak0em1em⁣ ( r 2 = 0.9771 ) For Cd ( II ) : E pa = prefix− 0.270 + 0.068 ln ( υ ) goodbreak0em1em⁣ ( r 2 = 0.9136 ) To complement these results, eq is evaluated using the potential difference between E pa and E p 1/2 (Figure A), where E p 1/2 corresponds to the potential at half of the peak current (α = 0.50). E normalp normala − E p 1 / 2 = 0.0477 α × n The obtained results confirm a two-electron transfer process for the Cd(II) ( n = 2.3∼2) and Zn(II) ( n = 2.1∼2) oxidations …”

Selective determination of nitrite in water and food samples using zirconium oxide (ZrO2)@MWCNTs modified screen printed electrode

“…Afterward, using eqn (2), where E p/2 = the half-peak potential, and E p = the standard potential.| E p/2 − E p | = 1.857( RT/αF ) α was calculated to be 0.0795, and the n was estimated to be 1.89–2 electrons, which matches with the previous reported finding. 39 Thus, the proposed voltammetric oxidation mechanism of nitrite on two electrons could be presented as follows:NO 2 − + H 2 O → NO 3 − + 2H + + 2e − …”

Complete Degradation of Glassy Carbon Microspheres into Carbon Nanostructures: Implications for Sensing

“…Glassy carbon (GC), also known as vitreous or polymeric carbon, is produced by thermal treatment (undergoing slow curing and carbonization and then heating to elevated temperatures) of carbon-rich polymers, such as phenolic resins or furfuryl alcohol resins in an inert atmosphere. , GC has been commonly recognized to have many distinguishing physical and chemical properties, such as high thermal stability, relatively low density, impermeability to gas and liquid, high resistance to graphitization, unusual hardness, very low electrical resistivity, and good chemical inertness . Thanks to these good properties, GC has been widely used in a variety of fields, especially in electrochemistry, − and in medical applications. , In order to explain these unusual performances, the structures of GC have been explored constantly for decades. There are several models for GC microstructures, mainly including graphitic carbon ribbon models and fullerene-related carbon models. − Jenkins and Kawamura proposed a model, in which GC consisted of narrow curved and twisted graphitic carbon ribbons .…”