The roles of the ruthenium concentration profile, the stabilizing component and the substrate on the stability of oxide coatings

On the deactivation mechanism of RuO2–TiO2/Ti anodes prepared by the sol–gel procedure

“…The same amount of coating of the same composition was prepared by the conventional thermal decomposition [10,11] of RuCl 3 and TiCl 3 dissolved in 2-propanol. These samples were dried and annealed in air under the same temperature regime as in the case of the sol-gel prepared anode.…”

“…doi:10.1016/j.jelechem.2005.01.026 potential could be caused by (1) the growth of an insulating TiO 2 layer in the substrate/coating interface, originating from substrate corrosion and (2) the anodic dissolution of a catalytically active oxide species, RuO 2 , which enriches the coating surface with TiO 2 . Coating erosion can also be involved in deactivation process [10,11]. Coating morphology appeared to play an important role in the consideration of the cause of anode deactivation.…”

“…The anode service life and coating stability can be evaluated by an accelerated stability test (AST) [8,[10][11][12], which involves the electrolysis of dilute chloride solution at constant high current densities. The end of anode service life, i.e., the loss of electrocatalytic activity, is recognized as a sudden increase in the potential.…”

Differences in the electrochemical behavior of ruthenium and iridium oxide in electrocatalytic coatings of activated titanium anodes prepared by the sol-gel procedure

“…2 ATA coatings with RuO 2 and/or IrO 2 undergo degradation due to the electrochemical dissolution of noble metal oxide species. [3][4][5][6] Since these products of noble metal oxide degradation are soluble, the anode coating is gradually enriched in insulating TiO 2 during operation, since not only is this oxide already present as a stabilizing component of binary and/or ternary coatings, but it also comes from the coating substrate. These processes lead to anode passivation.…”

“…These processes lead to anode passivation. [3][4][5] The anode activity for the oxygen evolution reaction plays a key role in the process of anode degradation. 5,6 It is known that ATA with iridium oxide in the coating is more stable against passivation in the electrolysis of NaCl solutions than a binary RuO 2 -TiO 2 coating.…”