Influence of temperature on the hydrogen evolution reaction on Nickel in LiBr solution by means of polarization techniques

Refrigeration machines of Lithium Bromide need resistant alloys which support the aggressive conditions that cause corrosion problems and generate hydrogen in the cathodic reaction. Hydrogen formation is an important problem in the operating conditions of adsorption machines because they operate under vacuum condition and as a consequence of that hydrogen generation the efficiency of the system decreases. Nickel is one of the alloying elements of Stainless Steels and it is used as a conventional cathode for hydrogen generation processes. The objective of this work is to study the influence of temperature on the hydrogen evolution reaction (HER) on Nickel using different electrochemical techniques: Open Circuit Potential (OCP), potentiodynamic and galvano-static measurements and image analysis. The HER was study in 992 g/l LiBr at three different temperatures (25, 50 and 75 C). It was found that temperature improved electrocatalytic activity for the HER and reduced the energy consumption for hydrogen generation on nickel. The activation energy of the corrosion processes was governed by a diffusion mechanism. Nickel was spontaneously passive in heavy brine LiBr solutions and it remained passive after the hydrogen generation. (authors)