Boosting oxygen evolution reaction of hierarchical spongy NiFe-PBA/Ni3C(B) electrocatalyst: Interfacial engineering with matchable structure

Abstract Rational interfacial structure with excellent charge transfer and exposure of numerous active sites plays vital roles in heterogeneous catalysis. Herein, a hierarchical spongy electrocatalyst with active NiFe Prussian blue analogues and nickel carbides interface (NiFe-PBA/Ni3C(B)) is proposed and fabricated by a borate-assisted strategy. The unique structure and matchable interface benefit from the desorption of borate ligands in-situ during the pyrolysis and carbonization process. The optimal electrocatalyst composing of metal-organic framework (NiFe prussian blue analogues) in conjunction with a metallic transition carbide phase (nickel carbide) exhibits an ultra-low overpotential of only 196 mV at 10 mA cm-2 and a small Tafel slope of 30.1 mV dec-1 for OER in KOH. The robust water oxidation performance can be ascribed to the abundant adsorption sites and effective interfacial interaction. In addition, computational simulations further confirm that NiFe-PBA/Ni3C(B) is favorable for OER since the optimized electronic distribution and metal-3d orbitals interact around Fermi level at the interface. This research provides a new insight into rationally designing efficient electrocatalysts via morphology engineering and integrating different functional phase with complementary advantages for catalysis application.