Tafel Slope for Cathodic Reaction from Tafel Equation Calculator

Tafel Equation:

\[ \text{Tafel Slope} = \frac{-\text{Overpotential}}{\log_{10}\left(\frac{\text{Electric Current Density}}{\text{Exchange Current Density}}\right)} \]

Overpotential (η):

Electric Current Density (i):

A/m²

Exchange Current Density (i₀):

A/m²

Tafel Slope:

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1. What is the Tafel Equation?

The Tafel Equation describes the relationship between the current density through an electrode and the overpotential applied. It's fundamental in electrochemistry for understanding electrode kinetics and reaction mechanisms.

2. How Does the Calculator Work?

The calculator uses the Tafel equation for cathodic reactions:

\[ \text{Tafel Slope} = \frac{-\eta}{\log_{10}\left(\frac{i}{i_0}\right)} \]

Where:

\( \eta \) — Overpotential (V)
\( i \) — Electric current density (A/m²)
\( i_0 \) — Exchange current density (A/m²)

Explanation: The Tafel slope provides information about the electrode reaction mechanism and the rate-determining step in electrochemical processes.

3. Importance of Tafel Slope Calculation

Details: The Tafel slope is crucial for characterizing electrode kinetics, determining reaction mechanisms, and evaluating catalyst performance in electrochemical systems.

4. Using the Calculator

Tips: Enter overpotential in volts, current density and exchange current density in A/m². All values must be valid (current densities > 0).

5. Frequently Asked Questions (FAQ)

Q1: What does the Tafel slope indicate?
A: The Tafel slope provides information about the electrode reaction mechanism and the number of electrons transferred in the rate-determining step.

Q2: What are typical Tafel slope values?
A: Typical values range from 30-120 mV/decade depending on the reaction mechanism and electrode material.

Q3: Why is the negative sign used in the equation?
A: The negative sign accounts for the cathodic nature of the reaction where overpotential is negative for reduction reactions.

Q4: What affects the Tafel slope value?
A: Temperature, electrode material, electrolyte composition, and reaction mechanism all influence the Tafel slope value.

Q5: How accurate is the Tafel equation?
A: The Tafel equation provides good accuracy for well-behaved electrochemical systems but may deviate for complex multi-step reactions or at very low/high overpotentials.