Lattice oxygen-mediated Ni O O M formation for efficient oxygen evolution reaction in MOF@LDH core–shell structures
Ziqi Liu, Haoyu Li, Hung-Sen Kang, Alpha T. N’Diaye, Min Hwan Lee
Abstract
Two-dimensional (2D) layered double hydroxides (LDHs) are promising as an effective electrocatalyst towards oxygen evolution reaction (OER), but their poor conductivity and tendency to stack together limits their activity and durability as an electrocatalyst. Herein, a three-dimensional (3D) core–shell catalyst, in which numerous LDH nanoplates are vertically grown on cuboidal metal organic framework (MOF) structures, is synthesized through a facile one-pot reaction strategy. The representative electrocatalyst (CoNi-BDC@LDH) achieves an excellent OER performance (with an overpotential of 282 mV at 100 mA cm−2) and stability. A series of quasi-operando and ex-situ characterization reveals a lattice oxygen-mediated mechanism where Ni and its neighboring metal site collaboratively forms Ni-O-O-M (M = Ni, Co) bridges, and the high valence state of Ni facilitates O2 desorption from the bridges. The high OER performance is additionally attributed to γ-NiOOH and CoOOH phases, and a large electrochemically active surface area.