IrO2 nanoparticle-decorated single-layer NiFe LDHs nanosheets with oxygen vacancies for the oxygen evolution reaction

A hybrid oxygen evolution catalyst, IrO2@single-layer NiFe layered double hydroxides (SL-NiFe LDHs), is successfully synthesized by anchoring highly dispersed IrO2 nanoparticles to SL-NiFe LDHs nanosheets with oxygen vacancies. Typically, during the synthesis process, the functional group –NH2 from the external anchor formamide acts as a coordination site to control the nucleation and growth of nanoparticles, which can ensure high dispersion without aggregation of IrO2 on SL-NiFe LDHs. In addition, this reducing synthetic environment causes a large number of holes and grooves in the NiFe-LDHs nanosheets, which result in the formation of oxygen vacancies in the SL-NiFe LDHs. The loading of IrO2 nanoparticles and the formation of oxygen vacancies endow IrO2@SL-NiFe LDHs with excellent performance for the oxygen evolution reaction (OER). IrO2@SL-NiFe LDHs nanosheets display outstanding OER performance with an overpotential of 270 mV at a current density of 10 mA cm−2 and good stability. Density functional theory (DFT) calculations indicate that the hybridization of IrO2 and SL-NiFe LDHs accelerates the reaction step. Notably, the Ir sites at the edges are more conducive to the formation of oxygen, and the oxygen sites on SL-NiFe LDHs are more conducive to the cleavage of the O–H bond, thereby improving the OER activity. This work highlights a potential synthetic strategy that can combine nanoprecious metals with transition metals to prepare highly active electrocatalysts for efficient water oxidation reactions.