Modulating the Active Sites of Oxygen-Deficient TiO₂ by Copper Loading for Enhanced Electrocatalytic Nitrogen Reduction to Ammonia

The electrocatalytic nitrogen reduction reaction (NRR) provides a sustainable route for NH₃ synthesis. However, the process is plagued by the strong N≡N triple bond and high reaction barrier. Modification of catalyst surface to increase N₂ adsorption and activation is crucial. Herein, copper nanoparticles are loaded on the oxygen-deficient TiO₂, which exhibits an enhanced NRR performance with NH3 yield of 13.6 μg mg_cat^-1 h^-1 at -0.5 V versus reversible hydrogen electrode (RHE) and Faradaic efficiency of 17.9% at -0.4 V versus RHE compared to the pristine TiO₂. The enhanced performance is ascribed to the higher electrochemically active surface area, promoted electron transfer, and increased electron density originated from the strong metal-support interaction (SMSI) between Cu nanoparticles and oxygen-deficient TiO₂. The SMSI effect also results in lopsided local charge distribution, which polarizes the adsorbed N₂ molecules for better activation. This work provides a facile strategy toward the electrocatalyst design for efficient NRR under ambient conditions.