Interstitial polydopamine layer stabilizing catalysts/electrode interface for sustainable water oxidation

Abstract

Cobalt-based oxygen-evolving catalyst (Co-OEC) exhibits high catalytic activity for water oxidation in the neutral pH regime. However, as the externally applied potential toward oxidation is lowered, the catalyst is slowly dissolved and eventually decomposed from the electrode because of their poor interfacial compatibility. Here, we introduce an interstitial polydopamine (PDA) layer to strengthen the Co-OEC/electrode interface for sustainable catalytic activity. The PDA layer efficiently stabilizes the catalyst/electrode interface as a redox-active adhesive interlayer. Under high applied potential conditions, the oxygen evolving catalytic activity is reduced by 95 % in the absence of the PDA layer. On the other hand, the Co-OEC/PDA/ITO electrode keeps the catalytic activity above 70 % under the same condition because the redox mediation of PDA suppresses the dissolution of Co2+ ions. The PDA layer also promotes water oxidation catalysis presumably through proton-coupled electron transfer. It is expected that the redox-active PDA can be applied to various catalysts as a means to improve their microenvironments for enhanced catalytic activity and sustainability.