Regulation of defect structures has emerged as a powerful strategy for tailoring the electronic structures and reaction pathways of nanostructured electrocatalysts[1], as crystal defects can directly modulate metal—oxygen bond strengths and catalytic mechanisms. In particular, aliovalent substitution offers an effective and quantitative approach to defect engineering by inducing anion vacancies while maintaining charge neutrality. When combined with hybridization, defect-introduced conductive substrates can further amplify interfacial electronic interactions, providing a promising route to overcome the intrinsic activity and conductivity limitations of layered double hydroxides (LDHs). However, it is still unclear how defect-induced electronic modulation at hybrid interfaces controls the OER mechanism.

Herein, Ce³⁺substituted Ti_1-xCeN_1-δ—LDH nanohybrids are employed as a model system to elucidate the role of aliovalent-substitution-driven defects and interfacial interactions using density functional theory (DFT) calculations. Theoretical analyses reveal that Ce³⁺ substitution thermodynamically promotes nitrogen vacancy formation in the TiN lattice, generating localized Ce 4f – Ti t_2g electronic states that markedly strengthen interfacial electronic coupling with LDH. Bader charge analysis demonstrates a progressive increase in interfacial charge transfer from Ti_1-xCeN_1-δ to LDH upon Ce substitution and nitrogen vacancy formation, leading to a pronounced downshift of the Fe 3d and O 2p band centers in LDH. Notably, the reduced energy gap between the surface O 2p and Fe 3d band centers enhances metal—oxygen covalency, thereby promoting the lattice oxygen participation mechanism (LOM).

Free-energy calculations of the OER pathway further confirm that nitrogen-vacancy-containing Ti_1-xCeN_1-δ—LDH exhibits the lowest overpotential, as the energy barrier for oxygen vacancy formation during O₂ evolution is significantly reduced. And also, the highly activated lattice oxygen species reinforced by strong interficial bonding weaken the Ni/Fe—OH bonds in the LDH via an increase in the coordination number. This balanced activation of adsorbates and lattice oxygen establishes a defect-assisted, energetically favorable OER pathway. These theoretical insights demonstrate that aliovalent-substitution-driven defect engineering, synergistically coupled with hybridization, enables precise regulation of electrocatalytic operation mechanisms, offering a general design principle for high-performance LDH-based hybrid electrocatalysts.