Ir-Surface Enriched Porous Ir-Co Oxide Hierarchical Architecture for High Performance Water Oxidation in Acidic Media

摘要

The large-scale application of acidic water electrolysis as a viable energy storage technology has been hindered by the high demand of precious metal oxides at anode to catalyze the oxygen evolution reaction (OER). We report an Ir—Co binary oxide electro catalyst for OER fabricated by a multistep process of selective leaching of Co from Co-rich composite oxides prepared through thermal decomposition. The stepwise leaching of the Co component from the composites leads to the formation of macro- and mesoscale voids walled by a cross-linked nanoporous network of rod- and wedge-like building units of Ir—Co binary oxide with a rutile phase structure and an Ir-enriched surface. In comparison, Ir—Co binary oxide with similar composition prepared by direct thermal decomposition method exhibits a loose nanoparticle aggregation morphology with a Co-enriched surface. The cross-linked porous Ir—Co binary oxide from selective leaching is about 3-fold more active for the OER than that from direct thermal decomposition. Compared with pure Ir02 from thermal decomposition, the Co-leached binary oxide is ca. two times more active and is much more durable during continuous oxygen evolution under a constant potential of 1.6 V, thus showing a possibility of reducing the demand of the expensive and scarce Ir in OER electrocatalyst for acidic water splitting.