Hey all!
I've been messing around with making silver/silver chloride reference electrodes for a few days, as preample to a larger project of making a sweepable 3-electrode potentiostat for cyclic voltammetry analyses.
And today I've finally gotten them working!
See attached diagram for the general idea. The electrode body was made by cutting little discs of approx 1mm thick clay sheet and then letting them dry, and firing them in a gas flame (a few of them popped apart but some survived - use eye protection!!), then epoxying to the end of a 15cm lenght of 7mm glass tubing.
The silver electrode was made by coating a lenght of 1mm dia. 99.9% silver wire in silver chloride, this is best done by electrolysis, but the easiest option, and the one i used was to just put a lenght of the wire (bottom 5ish cm) in household hypochlorite bleach for an hour. a grey/blue coating is observed.
The wire was mounted in teh tube with some layers of wire insulation and bicycle valve latex tubing, whether the wire is centeredor leans against the edge of the tube doesn't seem to make any difference.
The tube is filled to ~3cm with concentrated potassium chloride solution and the wire inserted. When placed in sodium chloride solution, and tested against a similar electrode (I made two), there's only 2-3 mv between them. When measured against a copper foil electrode (reference positive they both measure 220 mv +-10mv.
I'm happy with this performance, although I do fear that iron oxide in the clay frit might give some strange signals in analytical voltammetry.
Anyway it was an interesting build!
--
Chris