FeOOH-induced electronic modulation of metal-organic framework-derived CoNi-ZLDH for overall water splitting

Developing and designing inexpensive and efficient bifunctional electrocatalysts with high activity and long-term stability is highly essential for overall water splitting (OWS). Herein, a facile synthesis route is demonstrated to produce a hierarchical nanostructure comprising MOF-based cobalt-nickel layered double hydroxides (CoNi-ZLDH) nanosheets (NSs). These NSs are further coupled with self-supported FeOOH nanoparticles (NPs) demonstrating remarkable stability and high efficiency for water electrolysis. The resulting FeOOH/CoNi-ZLDH electrocatalyst possesses high intrinsic activity and outstanding electrical conductivity along with well-defined 3D structure having enhanced active electrochemical surface area. The FeOOH/CoNi-ZLDH functioning as a bifunctional electrocatalyst exhibits excellent performance in both oxygen evolution reaction (OER) with an overpotential of 226 mV at 50 mA cm-2 and hydrogen evolution reaction (HER) with an overpotential of 203 mV at 10 mA cm- 2. It is worth noting that the FeOOH/CoNi-ZLDH possesses outstanding durability for the OER, lasting for more than 150 h at 50 mA cm-2 without any noticeable change in performance. Additionally, to drive the OWS, electrode system requires a cell voltage of only 1.645 V to reach at a current density of 10 mA cm- 2. Our work emphasizes the modulation of the local electronic structure of hollow hierarchical CoNi-ZLDH via strong interfacial interactions with FeOOH NPs for the rational design of efficient bifunctional electrocatalysts derived from MOF.