The platinum rod counter electrode is an auxiliary electrode with a short Ø1.0 mm platinum rod at the tip of an insulating body. In a three-electrode cell it closes the current circuit while the potential is measured against the reference electrode. Platinum is inert in most media, so the counter electrode reaction usually does not disturb the measurement.
The immersed surface is small: if the whole rod is in solution, about 0.16 cm² (5 mm) and 0.32 cm² (10 mm). The counter electrode area should not be much smaller than about three times the working electrode area, so choose it for small-volume cells, small working electrodes and low currents. For high currents, gas evolution or bulk electrolysis a platinum mesh, sheet or long wire is a better fit.
| Electrode type | Platinum rod counter (auxiliary) electrode with insulating body |
| Electrode material | Platinum |
| Rod diameter | Ø1.0 mm |
| Rod length | 5 mm (PT1005) or 10 mm (PT1010) |
| Approx. geometric area (side + end face) | PT1005: ≈0.16 cm² · PT1010: ≈0.32 cm² (if the whole rod is immersed) |
| Limitation | Because of the small area the counter electrode reaction may become limiting at high currents or in long electrolysis; choose a larger-area electrode then |
| Compatible media | Widely used as a counter electrode in aqueous acid media (e.g. H₂SO₄). In organic solvents the solvent compatibility of the insulating body must be checked separately |
| Platinum dissolution / redeposition | At high anodic potentials and in long or many-cycle experiments platinum can dissolve and redeposit on the working electrode; in tests of Pt-free catalysts this can make the activity look higher than it is. For such work prefer a graphite/glassy-carbon counter electrode or a separate compartment |
| Cleaning | After use rinse with a suitable solvent, then with high-purity water; check the surface for deposits and run a blank scan if cross-contamination is possible. Do not flame-anneal electrodes with a polymer body |
| Connection | Connects to the counter electrode (CE/auxiliary) lead of the potentiostat. Contact pin type and cell/cable fit can be confirmed before ordering |
| Custom production | On request (size) |
| Model | Description |
| PT1005 Ø1.0 × 5 mm | Platinum rod: Ø1.0 × 5 mm |
| PT1010 Ø1.0 × 10 mm | Platinum rod: Ø1.0 × 10 mm |
For sizes and specifications not listed above, you can request a custom quotation through the Quote Form.
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