Reinforcement of Electrocatalytic Oxygen Evolution Activity Enabled by Constructing Silver-Incorporated NiCo-PBA@NiFe-LDH Hierarchical Nanoboxes.

Complicated oxygen evolution reaction (OER) poses the bottleneck in improving the efficiency of hydrogen production through water electrolysis. Herein, an integrated strategy to modulate the electronic structure of NiFe layered double hydroxide (NiFe-LDH) is reported by constructing Ag-incorporated NiCo-PBA@NiFe-LDH heterojunction with a hierarchical hollow structure. This "double heterojunction" facilitates local charge polarization at the interface, thereby promoting electron transfer and reducing the adsorption energy of intermediates, ultimately enhancing the intrinsic activity of the catalyst. It is noteworthy that an exchange bias field is observed between NiCo-PBA and NiFe-LDH, which will be conducive to regulating the electron spin states of metals and facilitating the production of triplet oxygen. Additionally, the unique hierarchical nanoboxes provide a large specific surface area that ensures adequate exposure to adsorption sites and active sites. Profiting from the synergistic advantages, the overpotential is as low as 190 mV at a current density of 10 mA cm, with a low Tafel slope of 21 mV dec. Moreover, density functional theory (DFT) calculation further substantiated that the incorporation of Ag in the heterojunction can effectively reduce the adsorption energy of reactant intermediates and enhance the conductivity.