Engineering imperfections in MnFe-LDH through Ce doping to exploit 3d–4f electronic interactions for the realization of a high-performance bifunctional electrocatalyst for overall water splitting in a basic electrolyte

Bifunctional electrocatalysts that combine superior electrocatalytic activity with excellent stability are prerequisites for facilitating efficient electrochemical water splitting. This work reports the synthesis of a binder-free cerium-doped manganese–iron layered double hydroxide electrocatalyst on nickel foam (MnFeCe-LDH/NF) via a facile hydrothermal method. The as-prepared material exhibits a unique hierarchical nanosheet array that self-assembles into a three-dimensional network on NF, providing abundant active sites, enhanced conductivity, shortened ion diffusion pathways, and improved electrolyte penetration. In addition, the Ce doping serves to modulate the electronic structure of MnFe-LDH through 3d–4f interactions, thereby promoting surface reconstruction of MnFe-LDH to highly electrocatalytically active crystalline MnOOH and FeOOH species, controlling the leaching of active sites, and optimizing adsorption energetics. In 1.0 M KOH, the optimized MnFeCe-LDH/NF requires overpotentials of 46 mV (10 mA cm⁻²) and 141 mV (100 mA cm⁻²) for the oxygen evolution reaction and 138 mV and 233 mV for the hydrogen evolution reaction at the same current densities. MnFeCe-LDH/NF shows excellent stability after surface reconstruction to MnOOH/FeOOH during chronopotentiometry and amperometry over 80 h in 1.0 M KOH, due to strong adhesion to NF, thereby confirming its eligibility as a durable binder-free and bifunctional electrocatalyst. As an electrolyzer, it achieves 10 mA cm⁻² at 1.43 V. Consequently, this work establishes a new paradigm for designing economical and efficient bifunctional electrocatalysts for water splitting technologies.