Johnson Matthey Public Limited Company

Other

Peter M Willis

Barry A Murrer

John Overstall

Ralph L Phillips

A process for making a polymer-modified electrode comprising electrocatalytic metal, a metal substrate (1) and small polymer particles (2) by contacting the substrate with a (preferably aqueous) dispersion containing the particles and also a dissolved compound of electrocatalytic metal of greater electronegativity than the metal of the substrate, whereby contacting the substrate with the dispersion cause spontaneous deposition of electocatalyst, which in turn causes desposition of the particles onto the substrate, and then drying the substrate and deposit at a temperature below the softening point of the polymer. The deposited particles retain their shape and only a few are mutually contiguous, with the result that the poison resistance of the electrodes is increased and their overpotentials are reduced. Also, electrodes in which at least 70% of the particles are fully spaced from their neighbors and the amount of particles deposited is preferably from 0.0005 to 2 cm.sup.3 m.sup.2 of substrate surface. The electrodes are useful as chloralkali cathodes.

Process for making a polymer-modified electrode and process using same

A cathode suitable for use in an electrochemical process evolving hydrogen (for example the chloralkali process) in which the cathode comprises an electrically conductive substrate (1) made of a non-ferrous metal or having a coherent coating of non-ferrous metal on which is provided an electrocatalyst (4) comprising platinum and ruthenium and wherein the cathode is made more poison-resistant by a deposition of gold or silver and, optionally, a further deposition of PTFE. The cathode is particularly resistant to poisoning by iron.

Cathodes suitable for use in electrochemical processes evolving hydrogen

Apparatus for measuring electrical potential in a cell, especially at a point close to a sample electrode, comprises an accommodation for a reference electrode, a modified luggin tube, elements for locating the sample electrode, and supports for both the luggin tube and the locating elements, respectively, the supports being fixed relative to each other. The apparatus requires less skill in the positioning of the sample electrode close to the point at which electrical potential is measured and is less vulnerable to inadvertent disturbance.

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Oxfordshire, United Kingdom

Peter M Willis