Synergistic redox coupling of Ce₂O₃ and Cu₂O in a NiFe-LDH ternary heterostructure for efficient oxygen evolution

Layered double hydroxides (LDHs), particularly NiFe-LDH, are promising electrocatalysts for the oxygen evolution reaction (OER) in water splitting, yet they suffer from limited stability and sluggish kinetics. Herein, we report a ternary heterostructure composed of NiFe-LDH nanosheets integrated with Ce₂O₃ nanoparticles on a Cu₂O-modified copper foam substrate (Ce₂O₃-LDH/Cu₂O). The redox coupling between Ce₂O₃ and Cu₂O synergistically enhances electronic conductivity, accelerates charge transfer, and promotes a favorable adsorbate evolution mechanism (AEM) pathway. The optimized catalyst, with 10 wt% Ce₂O₃, achieves an overpotential of only 231 mV at 10 mA cm^-2. Moreover, it retains 95% of its initial current density after 35 h of continuous operation, demonstrating exceptional durability. Mechanistic studies reveal that the Ce³⁺/Ce⁴⁺ and Cu⁺/Cu⁰ redox couples induce strong electronic interactions at the heterointerfaces, facilitating deep structural evolution of NiFe-LDH into active (oxy)hydroxide species. This work provides a new strategy for designing non-precious metal electrocatalysts with enhanced activity and stability via dual metal oxide redox coupling.