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Temperature-Dependent Kinetic Studies of the Chlorine Evolution Reaction over RuO 2 (110) Model Electrodes

2017; American Chemical Society; Volume: 7; Issue: 4 Linguagem: Inglês

10.1021/acscatal.6b03415

2155-5435

Iman Sohrabnejad‐Eskan, Andrey Goryachev, Kai S. Exner, Ludwig A. Kibler, Emiel J. M. Hensen, Jan P. Hofmann, Herbert Over,

Advanced battery technologies research

Ultrathin single-crystalline RuO2(110) films supported on Ru(0001) are employed as model electrodes to extract kinetic information about the industrially important chlorine evolution reaction (CER) in a 5M concentrated NaCl solution under well-defined electrochemical conditions and variable temperatures. A combination of chronoamperometry (CA) and online electrochemical mass spectrometry (OLEMS) experiments provides insight into the selectivity issue: At pH = 0.9, the CER dominates over oxygen evolution, whereas at pH = 3.5, oxygen evolution and other parasitic side reactions contribute mostly to the total current density. From temperature-dependent CA data for pH = 0.9, we determine the apparent free activation energy of the CER over RuO2(110) to be 0.91 eV, which compares reasonably well with the theoretical value of 0.79 eV derived from first-principles microkinetics. The experimentally determined apparent free activation energy of 0.91 eV is considered as a benchmark for assessing future improved theoretical modeling from first principles.