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.