The Active Interface of Iron-Decorated Cobalt (Oxy)Hydroxide for Oxygen Evolution Reaction

Abstract

Iron can significantly enhance the activity of Co (oxy)hydroxide. However, the nature of active sites is currently under debate for Fe-Co (oxy)hydroxide. Here, we use well-define crystalline cobalt hydroxide nanosheets and nanorods as model catalysts to investigate the role of Fe on different crystal planes. The electrochemical reactivity and morphology-dependent analysis suggest that the lateral facets of Co(OH)2 are active sites and the enhancement effect of iron incorporation only occurs on lateral facets rather than basal facets. Furthermore, by introducing tetramethylammonium cation (TMA+) as a chemical probe in KOH solution, we demonstrate the Fe species can interact strongly with the “active species” on the lateral facets and promote the improvement of OER activity. This work identifies the active site of cobalt hydroxides in the presence and absence of iron and elucidates the interaction of Fe species with “active oxygen” species on the lateral facets of cobalt hydroxide, which has a fundamental implication on the design of efficient OER catalysts.