Definition - What does Potentiostaircase mean?
A potentiostaircase is a potentiostep technique for polarizing an electrode in a series of constant potential steps wherein the time duration and potential increments or decrements are equal for each step. It is a variation of potentiodynamic polarization in corrosion testing.
A potentiostaircase is a polarization method similar to cyclic voltametry, and the two are often used for laboratory corrosion testing. These techniques can provide significant useful information regarding corrosion mechanisms, corrosion rate and susceptibility of specific materials to corrosion in designated environments.
Corrosionpedia explains Potentiostaircase
Several methods may be used in polarization of specimens for corrosion testing. The potentiostaircase method is one in which an electrode is polarized in a series of potential steps where the time spent at each potential is constant, while the current is often allowed to stabilize prior to changing the potential to the next step. The step increase may be small, in which case, the technique resembles a potentiodynamic curve, or it may be large.
Additionally, the time frames involved are usually very short compared to the projected life. Unfortunately, long-term potentiostatic testing is extremely time-consuming and expensive.
In staircase polarization the potential sweep is a series of stair steps. The current is measured at the end of each potential change, right before the next, so that the contribution to the current signal from the capacitive charging current is minimized. The differential current is then plotted as a function of potential, and the reduction or oxidation of species is measured as a peak or trough.
A potentiostaircase involves sweeping the potential of the working electrode linearly with time at rates faster than cyclic voltametry, typically between 10 V/s and 100 V/s.
Potentiostaircases generate high sweep rates. High sweep rates have three advantages:
- Allow for the detection of species while preventing the formation of an insulating layer
- Allow extracellular detection
- Discriminate against chemical events after the initial electron transfer.
Potentiostaircase tests can be performed in lieu of potentiodynamic tests, though at equivalent potential scan rates, the results should be identical.