A study has been made to determine the potential of a mixed nickel-hydrogen electrode containing up to about 0.7 H atoms per N'i atom. Nickel layers electrodeposited on copper foils were charged cathodical]y in sulfuric acid solutions containing thiourea or selenium dioxide as catalytic poisons of the hydrogen recombination reaction. The electrode potential of nickel charged with hydrogen and kinetics of decomposition of the hydride phase were studied as functions of time of hydrogen desorption and pH of the electrolyte. The results show that the nickel-hydrogen system behaves electrochemically like the palladiumhydrogen system. The open-circuit potential of NiH0.4, i.e., of a nickel-hydrogen electrode presumably containing a mixture of alpha and beta phases, is a linear function of pH, with a value approximately 0.13v less noble than that of the hydrogen electrode. The desorption rate of hydrogen from Ni-H depends on the pH. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.226.37.5 Downloaded on 2015-06-02 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 128.226.37.5 Downloaded on 2015-06-02 to IP

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Measurements of the permeation rate of electrolytic hydrogen through steel membranes have shown that compounds of P, As, Sb, S, Se, and Te enhance the entry of hydrogen into the steel only under conditions resulting in the formation of hydrides of hydrides of these elements. It may be presumed that the hydrides which are dissociatively chemisorbed on the cathode are able to assit in the transmission of hydrogen atoms across the electrolyte metal interface, while adsorbed hydroxylions, may be presumed to interfere with the action of hydrides and thus to inhibit permeation.