Muhammad Izuan Nasib, the Warburg impedance is a common feature observed in electrochemical impedance spectroscopy (EIS) measurements, particularly in systems involving diffusion-limited processes, such as electrode reactions involving faradaic processes at the electrode-electrolyte interface. The Warburg impedance is typically represented by a straight line with a 45-degree slope on a Nyquist plot, also known as a Warburg plot.

When you observe a straight line with a 45-degree slope in a Warburg plot, it indicates a Warburg diffusion-limited process. Here's how you can interpret this characteristic:

In summary, a straight line with a 45-degree slope in a Warburg plot indicates that the system's electrochemical behavior is influenced by diffusion-limited mass transport. This information can provide insights into the kinetics and transport processes occurring at the electrode-electrolyte interface, guiding the interpretation of the electrochemical system under study.

Dear Muhammad,

Could you provide further details about the measurements? More than resembling a Warburg element, it appears to be more like a significantly large semicircular shape. However, for a proper visual analysis, it's essential to represent the X-axis and Y-axis on the same scale at the very least.

Best regards,

Dmitry

Hello Muhammad!

Your EIS impedance spectra show the classical response for solution resistance in serial connection with a constant phase element.

If you increment the frequency range in your measurement, you can observe a loop that you can relate with a charge transfer resistance in parallel to the constant phase element.

However, how was your measurement carried out? Is it in a three-electrode cell? The working electrode was modified with the composites? This information is required to develop an adequate interpretation

For me, the behavior observed in your diagram can not be associated with Warburg impedance for the following two reasons:

i) The frequency range used in your measurement is too short to observe diffusion response. It classically appears at frequencies around 0.1 Hz or lower. Furthermore, the characteristic of Warburg diffusion is that Z"=Z', which is the reason that Warburg impedance reaches a phase angle of 45º. It seems to me that the previously mentioned behavior is not observed in your diagram.

ii) There is no diffusion expected in your materials, or is it?

Best wishes