Engineering Self-Reconstruction via Flexible Components in Layered Double Hydroxides for Superior-Evolving Performance.

Most transition metal-based catalysts for electrocatalytic oxygen evolution reaction (OER) undergo surface reconstruction to generate real active sites favorable for high OER performance. Herein, how to use self-reconstruction as an efficient strategy to develop novel and robust OER catalysts by designing pre-catalysts with flexible components susceptible to OER conditions is proposed. The NiFe-based layered double hydroxides (LDHs) intercalated with resoluble molybdate (MoO4 2- ) anions in interlayers are constructed and then demonstrated to achieve complete electrochemical self-reconstruction (ECSR) into active NiFe-oxyhydroxides (NiFeOOH) beneficial to alkaline OER. Various ex situ and in situ techniques are used to capture structural evolution process including fast dissolution of MoO4 2- and deep reconstruction to NiFeOOH upon simultaneous hydroxyl invasion and electro-oxidation. The obtained NiFeOOH exhibits an excellent OER performance with an overpotential of only 268 mV at 50 mA cm-1 and robust durability over 45 h, much superior to NiFe-LDH and commercial IrO2 benchmark. This work suggests that the ECSR engineering in component-flexible precursors is a promising strategy to develop highly active OER catalysts for energy conversion.