Electronically regulated FeOOH/c-NiMoO4 with hierarchical sandwich structure as efficient electrode for oxygen evolution and hybrid supercapacitors

Electronic regulation via interface engineering is an effective strategy to promote electrochemical performances of nanomaterials. This work reported a facile method to prepare sandwich-like FeOOH/c-NiMoO4 with FeOOH as the mid-layer and the composite of NiMoO4-Ni(OH)2 nanosheets on both sides of FeOOH. Benefiting from the novel hierarchical porous structures and compositional features, the obtained FeOOH/c-NiMoO4 showed excellent electrochemical performances as electrodes for oxygen evolution reaction (OER) and hybrid supercapacitors (HSCs). It demonstrates excellent OER performances with an overpotential of 254 mV to reach the current density of 10 mA cm−2, a Tafel slope of 58 mV dec−1, and a low applied potential difference of 1.51 V at 10 mA cm−2 for overall water splitting and yields a high specific capacity of 1137 C g−1 (specific capacitance of 2273 F g−1) at 1 A g−1 for SCs in an alkaline electrolyte. First-principle calculations were employed to explore the origin. This work manifests the feasibility of rational design of multi-functional materials via electronic modulation for overall water splitting and energy-storage devices.