Thin Film Coating of Mg-Intercalated Layered MnO2 to Suppress Chlorine Evolution at an IrO2 Anode in Cathodic Protection

Titanium-supported electrocatalysts composed of novel metal oxides have exclusively been utilized as anodes in the cathodic protection (CP) of steel structures. These types of anodes have a small overpotential toward the chlorine evolution reaction (CER) in impressed-current cathodic protection (ICCP) systems and vigorously evolve chlorine (Cl 2 ) in electrolytes containing Cl − , such as seawater. Cl 2 has a negative impact on the ecosystem because of its intrinsic toxicity and corrosivity. We present herein a thin film coating that can effectively suppress the CER without prevention of the oxygen evolution reaction (OER) at the underlying iridium oxide (IrO 2 ) layer coated on a titanium substrate in 0.5 M NaCl solution. The thin film consists of buserite-type layered manganese dioxide (MnO 2 ), the interlayer of which accommodates Mg 2+ cations and two layers of H 2 O molecules, and is uniformly deposited via an electrochemical route and subsequent ion-exchange. The CER efficiency of the electrode modified with the Mg-buserite layer was as small as 11% at + 1.7 V vs. Ag/AgCl. Graphical Abstract Thin film coating of Mg-intercalated layered MnO 2 to suppress chlorine evolution at an IrO 2 anode in cathodic protection by Hikaru Abe, Tamie Kobayakawa, Heishi Maruyama, Toru Wakabayashi, Masaharu Nakayama*.