Structure of the electrode interface

Question 1

What is a Inner sphere?

Answer 1

A redox chemical reaction that proceeds via a covalent linkage. Typical of electrocatalysis

Question 2

What is a Outer sphere?

Answer 2

Chemical species that remain separate and intact before, during, and after the ET event.

Question 3

Draw the inner / outer sphere diagram

Answer 3

Question 4

What does the electrode interface usually look like?

Answer 4

Question 5

What are the 3 interface models?

Answer 5

1. Helmholtz (H) (inner layer)
2. Gouy-Chapman (GC) (outer layer)
3. Gouy–Chapman–Stern (GCS) (both layers)

Question 6

Explain the Gouy-Chapman layer

Answer 6

1. Layer extends some distance into the liquid dispersing phase
2. Diffuses with a gradual fall in potential into bulk of the liquid
3. Takes into account thermal motion of the ions in solution
4. Balance between electrostatic forces (Poisson/Gauss) and thermal motion (Boltzmann)

Question 7

Draw Gouy–Chapman–Stern Model diagram

Answer 7

Question 8

What is double layer capacitance?

Answer 8

Current from the charge and discharging of the double layer

Non-Faradaic current – arises from a process that does not involve charge transfer (oxidation or reduction) at the surface

Question 8

What equation is Non-Faradaic current

Answer 8

Question 9

Draw the diagram showing solution resistance

Answer 9

Question 10

What is the equation for total current?

Answer 10

Question 11

Draw current graph of capacitive and Faraday current

Answer 11