Self-supported coaxial nanocable CuO@Ni(OH)2@FeOOH heterojunction arrays catalyst with interfacial coupling for enhanced oxygen evolution and urea oxidation reactions

It is of essential importance to exploit electrocatalysts with excellent performance for anodic reactions in electrochemical water splitting, such as oxygen evolution reaction (OER) and urea oxidation reaction (UOR). Herein, we delicately constructed a coaxial nanocable-like structure containing Cu foam-supported CuO NWs as core and Ni(OH)₂@FeOOH heterogeneous nanosheets as a porous sheath (i.e., CuO@Ni(OH)₂@FeOOH NWs/CF). The particular architecture with 1D nanoarray frameworks in-situ grown on 3D conductive substrate and hierarchical microstructure ensures the adequate exposure of the active sites, facilitative electron/mass transfer, and high structural stability. Combined experimentation and DFT calculation demonstrate that Ni(OH)₂ and CuO in the hybrid served as active metal ions and scaffold for providing a fast electron conducting path, respectively. Meanwhile, FeOOH acted as an inductive agent to attract charge reorganization of adjacent Ni sites, thus modulating the electron structure and optimizing the d-band centers. Strengthened by the above desirable characteristics, CuO@Ni(OH)₂@FeOOH NWs/CF exhibited superior electrocatalytic activities towards both OER and UOR with a small overpotential of 310 mV and low potential of 1.37 V at 100 mA cm⁻², respectively, as well as the expected electrocatalytic stability. This work affords a way to design highly active catalysts via constructing heterojunctions for various applications.