Three-Dimensional Hierarchical Multimetal-LDH Nanoflakes and Their Derived Spinel Oxides for Efficient Oxygen Evolution

Electrocatalysts with three-dimensional (3D) hierarchical architectures, large surface areas, and coherent transmission routes are highly desired. In this work, hierarchical multimetal layered double hydroxide (LDH) nanoflakes based on earth abundant metals (Ni, Fe, and Co) have been fabricated through chemical and structural transformations of a starting solid precursor α-Co(OH)2. Herein, the surfactant sodium dodecylbenzenesulfonate (SDBS) adsorbed on the α-Co(OH)2 serves as both a protector to avoid the hydrolysis of hydroxide and an exfoliant to reconstruct the original α-Co(OH)2 platelets into much thinner nanoflakes. Furthermore, the derived spinel oxide sheets from the hierarchical CoNiFe-LDH can be endowed with numerous mesopores which improve the exposure of catalytic active sites and enhance mass transports of reactants and products of electrochemical processes. Tested for oxygen evolution reactions (OER), both the hierarchical CoNiFe-LDH and its derived spinel oxide nanoflakes display excellent electrocatalytic activities and good long-term durability.