RESEARCH INTO THE EFFECT OF ETCHING PROCESS OF POROUS TITANIUM CURRENT COLLECTORS IN HYDROCHLORIC ACID ON THE PERFORMANCE OF WATER ELECTROLYZERS WITH A PROTON EXCHANGE MEMBRANE

Abstract

Based on the modern methods of SEM, voltammetry, and gravimetric analysis, samples of current collectors used in electrolyzers with a solid polymer electrolyte, made of porous titanium with various degrees of etching in concentrated hydrochloric acid, were studied. A gravimetric study of the etching process of samples of various sizes from porous titanium showed that throughout the process there is a loss of mass of the sample, with the exception of two short intervals, presumably due to the formation of hydrides (60-80 sec) and oxides (4-5 min), and the samples of smaller volumes were more sensitive to weight loss and weight growth. The use of the SEM method made it possible to reveal that etching over different time intervals changes the structure of porous titanium, reducing the average particle size and increasing their porosity .In this case, the surface inhomogeneity increases due to the formation of cavities in titanium and deterioration of the contact of the current collector surface with the catalytic layer. The consequence of this is the difference in the current-voltage characteristics of electrolysis cells with different duration of etching of the current collectors: there is a decrease in the productivity of electrolysis with an increase in the duration of etching of the current collectors by ~8% for etching more than 1 minute and ~18% for etching more than 4 minutes as compared to the simultaneous immersion of the sample in acid to clean the surface.