Boosting charge transfer via interface charge reconstruction between amorphous NiFe-LDH and crystalline NiCo₂O₄ for efficient alkaline water/seawater oxidation

Electrocatalysts with optimal efficiency and durability for the oxygen evolution reaction (OER) are becoming increasingly important as the demand for alkaline water/seawater electrolysis technology grows. Herein, a novel rose-shaped NiFe-layered double hydroxide (LDH)/NiCo₂O₄ composed of amorphous wrinkled NiFe-LDH and highly crystalline NiCo₂O₄ was synthesized with rich heterointerfaces. Many unsaturated metal sites are generated due to significant charge reconstruction at the heterointerface between the crystalline and amorphous phases. These metal sites could trigger and provide more active sites. The density functional theory (DFT) reveals that a new charge transfer channel (Co-Fe) was formed at the heterointerface between NiFe-LDH as electron acceptor and NiCo₂O₄ as electron donor. The new charge transfer channel boosts interfacial charge transfer and enhances catalytic efficiency. The NiFe-LDH/NiCo₂O₄/nickel foam (NF) drives current densities of 10 and 100 mA·cm⁻² with overpotentials of 193 and 236 mV, respectively. The composite electrode demonstrates a fast turnover frequency (0.0143 s⁻¹) at 1.45 V vs. RHE (RHE = reversible hydrogen electrode), which is 5.5 times greater than pure NiCo₂O₄, suggesting its superior intrinsic activity. Additionally, NiFe-LDH/NiCo₂O₄/NF electrode exhibited negligible degradation after 150 h of uninterrupted running in alkaline seawater oxidation. This study introduces a method for preparing high-efficiency electrocatalysts utilized in alkaline water/seawater electrolysis.