Hierarchical Ce-doped NiMn-LDH nanoflowers: tailoring active sites via electrodeposition towards superior overall water splitting

This work addresses the critical challenges of expensive noble-metal catalysts and inferior conductivity of transition metal hydroxides in water electrolysis by developing in-situ grown NiMn layered double hydroxide (NiMn LDH/NF) self-supported electrodes through one-step electrodeposition on nickel foam. The engineered 2D porous nanosheet architecture delivers abundant active sites, achieving exceptional hydrogen evolution reaction (HER) performance with 17 mV overpotential at 10 mA cm-2. Furthermore, cerium doping strategy effectively regulates nucleation kinetics through Ce3+/Ce4+ redox couples, constructing flower-like hierarchical Ce-NiMn LDH/NF architecture. The optimized electronic structure and enhanced surface hydroxylation significantly boost oxygen evolution reaction (OER) kinetics, requiring merely 212 mV overpotential to deliver the current density of 50 mA cm-2. The NiMn LDH/NF||Ce-NiMn LDH/NF electrolytic system demonstrates exceptional performance for overall water splitting, achieving an ultralow cell voltage of 1.44 V at 10 mA cm-2. Remarkably, it retains 97.66 % of its initial activity after 100 h of continuous operation, underscoring the efficacy of the rare-earth cation-doped structural engineering strategy. This approach enables the rational design of high-performance, durable, and cost-effective electrocatalytic systems by synergistically optimizing electronic configurations, active site accessibility, and long-term stability.