IrO₂-Based Interlayers With High Oxygen Evolution Performance For Enhancing Electrochemical Stability Of DSA^?

Dimensionally stable anodes (DSA) have been widely used in antifouling, chlor-alkali industry, wastewater treatment and other fields for its excellent electrocatalytic performance. However, the poor stability of DSA restricts their service lifetime in electrolysis industries for electeode aging or even deactivation. The formation of passivated film may be responsible for DSA deactivation. The oxygen intermediate species can penetrate into the cracks of coatings and form passivated TiO2 layer between the coating and underlying titanium substrate. Therefore how to design DSAs with high activity and stability becomes an urgent problem to be solved. In this paper, the effects of electrochemical properties of interlayer on the stability of DSAs are characterized in detail.Firstly, the Ti/IrxPb1-xO2/RuIrSnO2 electrodes were prepared. The polarization curve, accelerated electrolysis lifetime and activation energy calculation show that the increase of Ir:Pb ratio in IrxPb1-xO2 interlayer tends to enhance the oxygen evolution reaction (OER) activity and stability of interlayer to some extent. Meanwhile, The service lifetime of RuIrSnO2 electrodes prolong significantly when the activity and stability of IrxPb1-xO2 interlayer increase. Besides, the service life of Ti/Iro.7Pbo.302/RuIrSn02 electrode is enhanced by 12.5 times than the national standard value.Secondly, the influence of IrO2-based interlayers on DSA stability is deeply explored. The results show that the mechanism of interlayers can be summarized as chemical shielding. The interlayers not only prevent erosive species from permeating into substrates, but also preferentially convert active oxygen species into oxygen gas on defect region for its higher OER activity.Base on this mechanism, another four Ti/IrO2-MexOy/RuIrSnO2 (Me=Sn, Ni, Mn, Co) electrodes with different IrO2-based interlayers are prepared. The results are similar to Ti/ IrxPb1-xO2/RuIrSnO2, further demonstrate the conclusion above. The higher the OER activity and stability of interlayer, the more stable the electrode. Besides, the acceletated lifetime of Ti/IrO2-Co3O4/RuIrSnO2 even reaches 731 h. Therefore, adding interlayers with outstanding activity and stability may be an effective strategy to prolong service lifetime of DSA. This research provides a new chemical shielding thought for the development of DSAs with high activity and stability in harh electrolysis industries.