Self‐Reconstruction Induced Electronic Metal‐Support Interaction for Modulated Cu⁺ Sites on TiO₂ Nanofibers in Electrocatalytic Nitrate Conversion

The Cu⁺ active sites have gained great attention in electrochemical nitrate reduction, offering a highly promising method for nitrate removal from water bodies. However, challenges arise from the instability of the Cu⁺ state and microscopic structure over prolonged operation, limiting the selectivity and durability of Cu⁺-based electrodes. Herein, a self-reconstructed Cu₂O/TiO₂ nanofibers (Cu₂O/TiO₂ NFs) catalyst, demonstrating exceptional stability over 50 cycles (12 h per cycle), a high NO₃ ^--N removal rate of 90.2%, and N₂ selectivity of 98.7% is reported. The in situ electrochemical reduction contributes to the self-reconstruction of Cu₂O/TiO₂ nanofibers with stabilized Cu⁺ sites via the electronic metal-support interaction between TiO₂ substrates, as evidenced by in situ characterizations and theoretical simulations. Additionally, density functional theory (DFT) calculations also indicate that the well-retained Cu⁺ sites enhance catalytic capability by inhibiting the hydrogen evolution reaction and optimizing the binding energy of ^*NO on the Cu₂O/TiO₂ NFs heterostructure surface. This work proposes an effective strategy for preserving low-valence-state Cu-based catalysts with high intrinsic activity for nitrate reduction reaction (NO₃RR), thereby advancing the prospects for sustainable nitrate remediation technologies.