Reference electrode
While the SHE might seem to be a reasonable reference for nonaqueous work as it turns out the platinum is rapidly poisoned by many solvents including acetonitrile [3] causing uncontrolled drifts in potential.
While for short periods it may be possible to use such aqueous electrodes as references with nonaqueous solutions the long-term results are not trustworthy.
[4] The best argument against using aqueous reference electrodes with nonaqueous systems, as mentioned earlier, is that potentials measured in different solvents are not directly comparable.
Since QREs are made fresh, there is also no concern with improper storage or maintenance of the electrode.
Yttria-stabilized zirconia (YSZ) membrane electrodes were developed with a variety of redox couples, e.g., Ni/NiO.
When the pH value is known, these electrodes can be employed as a reference with notable applications at elevated temperatures.
1) Platinized platinum electrode,
2) Hydrogen gas,
3) Acid solution with an activity of H + = 1 mol/L,
4) Hydroseal for prevention of oxygen interference,
5) Reservoir via which the second half-element of the galvanic cell should be attached. The connection can be direct, through a narrow tube to reduce mixing, or through a salt bridge , depending on the other electrode and solution. This creates an ionically conductive path to the working electrode of interest.
