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Free keywords:
energy efficiency; electrocatalysis; morphology; SECM; activity; stability
Abstract:
The efficiency of electrocatalytic gas evolving reactions (hydrogen, chlorine and oxygen evolution) is a key challenge for important industrial processes, such as chlor-alkali electrolysis or water electrolysis. The central issue for the aforementioned electrocatalytic processes is their huge power consumption. Experimental results accumulated in the past, as well as some predictive models ("volcano" plots) indicate that altering the nature of the electrode material cannot significantly increase the activity of the mentioned reactions. Consequently, it is necessary to find a qualitatively different strategy for improving the energy efficiency of electrocatalytic gas evolving reactions. A usually disregarded fact is that gas evolution is an oscillatory phenomenon. Given the oscillatory behavior, a key parameter of macrokinetics of gas electrode is the frequency of gas-bubble detachment. Bearing in mind that gas evolution greatly depends on the surface morphology, a methodology is proposed that establishes a rational link between the morphological pattern of an electrode with its activity and stability. Characterization was performed using advanced analytical tools. The frequency of gas-bubble detachment was obtained in the configuration of scanning electrochemical microscopy (SECM), while the corrosion stability was analyzed using a miniaturized scanning flow electrochemical cell connected to a mass spectrometer (SFC-ICPMS).
