Heterostructure of ultrafine FeOOH nanodots supported on CoAl-layered double hydroxide nanosheets as highly efficient electrocatalyst for water oxidation.

The supported and dispersed ultrafine active species for electrocatalytic water oxidation are quite promising for the high intrinsic activity. A novel heterostructure of ultrafine FeOOH nanodots with an average size of 2.3 nm supported on CoAl-LDH nanosheets, is constructed by a facile method under ambient conditions. The as-prepared FeOOH@CoAl-LDH shows a strong interfacial interaction upon the formation of heterostructure, and is demonstrated as a highly efficient and stable electrocatalyst that demands 272 mV to attain 50 mA cm-2 and exhibits a Tafel slope of 40 mV dec-1. Moreover, density functional theory calculations manifest the coupling of FeOOH with CoAl-LDH can effectively decrease the energy barrier during the water oxidation process by optimizing the adsorption free energy of intermediates in the reaction pathway. The successful development of FeOOH@CoAl-LDH can shed light on the design of novel electrocatalysts that can fully take advantages of small size, heterostructure and synergistic effect.