Electrical precipitators electrode insulators

The formation of a platinum oxide surface layer as given in Eq. (20.6) prevents dissolution or precipitation of platinum according to Eq. (20.5), since dissolution of platinum oxide as shown by Eq. (20.7) is rather slow [14, 15]. Precipitation of Pt + ions by reaction with hydrogen may occur within the membrane, forming an electrically insulated Pt band [16]. Platinum losing electrical contact with the electrode is referred to as catalyst islanding [17]. The electrochemically active platinum surface area decreases because of these mechanisms, resulting in performance... 

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