Integrated in-situ construction of electrode matrix and surface amorphous Ni-Co-Fe LDH catalytic layer for efficient water splitting

To address the limited activity and durability of oxygen evolution reaction (OER) electrocatalysts, we present an integrated in situ strategy for constructing a three-dimensional Ni-Co dendritic electrode matrix coupled with a surface amorphous Ni-Co-Fe layered double hydroxide (LDH) catalytic layer. A Ni-Co dendritic matrix (NCDEM) with enhanced electrolyte accessibility and mass transport properties is first fabricated via jet electrodeposition, followed by the in situ hydrothermal growth of Ni-Co-Fe LDH nanosheets to construct a Ni-Co-Fe dendritic electrode (NCFDE). The introduction of NaBO₂ during the hydrothermal process regulates surface etching kinetics and the Fe³ ⁺ coordination environment, promoting uniform nanosheet growth and triggering the crystalline-to-amorphous transition of the LDH structure. The amorphous LDH layer increases the accessible active surface area, facilitates the formation of reconstructed NiOOH active species during OER, and enhances structural stability during prolonged electrochemical operation. The optimized B2-NCFDE exhibits outstanding OER performance in 1 M KOH, requiring an overpotential of only 215.34 mV to achieve 100 mA cm⁻², with a Tafel slope of 38.29 mV dec⁻¹ and stable operation at 500 mA cm⁻² for 2000 h. Furthermore, the B2-NCFDE||B2-NCFDE electrolyzer achieves 100 mA cm⁻² at a cell voltage of 1.822 V and demonstrates excellent durability for overall water splitting. This work provides a scalable strategy that integrates electrode architecture engineering with amorphous LDH regulation for efficient and durable hydrogen production.