Kinetics of electrodeposition and catalytic activity of thin films of ruthenium

It is shown that a single layer only, of ruthenium, is deposited electrochemically on to mercury from acid solutions of ruthenium chloride. Evidence is presented that the layer has half the thickness of unit lattice repeat in the c0 direction of the close-packed hexagonal lattice and that it is formed by the two-dimensional growth of centres, nucleated in the initial stages of electrodeposition on the substrate electrode. The electrodeposition is accompanied by catalytic hydrogen evolution and this process is restricted to the edges of the growth centres, the surface of the fully-formed film having low catalytic activity. The characteristics of the catalytic hydrogen evolution are similar to those which have been observed on bulk platinum metals; high rates of reaction may be reached at the catalytic sites.