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(sic)N triple bond and high reaction barrier. Modification of catalyst surface to increase N-2 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 mu g 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 N-2 molecules for better activation. This work provides a facile strategy toward the electrocatalyst design for efficient NRR under ambient conditions.