Tungsten oxide decorating-regulated iron-nickel oxide heterostructure as electrocatalyst for oxygen evolution reaction

The development of efficient and long-term stable electrocatalysts for oxygen evolution reaction (OER) is the key to harness hydrogen energy by water electrolysis. In this work, tungsten oxide decorated iron-nickel oxide heterostructure was grown on nickel skeleton by hydrothermal synthesis through simultaneously chemical etching reaction and decomposition of transition metal oxalate, forming porous WO ₃/Fe ₂O ₃-NiO/NF composite. The decoration of WO ₃ creates WO ₃/Fe ₂O ₃ -NiO heterostructure interface with high-density heterometal-oxygen bridge sites, which can effectively modulate the intrinsic electronic structure of the catalyst and optimize the adsorption energy of the reaction intermediates, thus accelerate the OER through the adsorbate evolution mechanism. In addition, abundant oxygen vacancy (V _O) sites induced by high valence W ⁶⁺ further boost OER activity through the lattice oxygen-mediated mechanism. With the unique porous interfacial structure, the as-synthesized WO ₃/Fe ₂O ₃ -NiO/NF exhibits remarkable OER electrocatalytic activity with low overpotential of 211 mV at OER current density of 100 mA cm ^-2, and high stability at 100 mA cm ^-2 with overpotential fluctuates within ± 2.8% range during the 100 h test. The as-proposed method is effective in lowering the overpotential of OER, and may be applicable for other electrochemical energy conversion applications.