Electrochemical properties of proton-exchange membrane in process of hydrogen production
Electrolysis is considered as the cleanest way to produce hydrogen, when the required electricity is derived from renewable energy sources. Currently two main types of low-temperature electrolysers exist, which have been developed on the market, namely alkaline and proton exchange membrane. The main difference is in electrolyte used inside a cell, accordingly liquid or solid polymer [1, 2] . Single cell used for electrolysis in this research was built with Nafion117 catalyst coated membrane
... coated membrane (CCM)  . Materials used for producing membranes are sulphonated fluoropolymers, in general perfluorosulfonic acid (PFSA), which is a result of substitution fluorine in fluoroethylene and sulfonation process (adding side chain ending with sulphonic acid). Membrane thickness is usually in range of 50 -250 μm , one used in experiment had 183μm. The electrochemical properties of a PEM electrolyser were investigated at different temperatures, including hydrogen production rate for few current density values. The Faradic and electrical efficiencies were determined. The decomposition voltage values for both temperatures were obtain (Fig.1) as well as the polarization curves for two cases (Fig.2) . Degradation of hydrogen production rate was observed as a result of self-heating of cell which indicate a need for more complex control system for industrial scale electrolysers (Fig.3) . Fig. 1. Estimation of decomposition voltage of the PEM cell for two temperatures, namely 24°C and 60°C.