Harnessing interfacial synergy between bimetallic nanoparticles and oxygen-deficient oxide nanofibers toward...

Designing high-performance electrocatalysts toward the nitrate reduction reaction (NO₃RR) is essential for sustainable ammonia (NH₃) production. In this study, we have developed a hybrid catalyst with bimetallic CuAg nanoparticles (NPs) anchoring on oxygen vacancies (OVs)-rich TiO₂ nanofibers (CuAg@TiO₂ NFs) via an in-situ reduction route. Experimental results demonstrate that the bimetallic CuAg@TiO₂ NFs catalyst presents accelerated pre-reaction kinetics toward NO₃RR compared to its monometallic analogues (Cu@TiO₂ and Ag@TiO₂ NFs), attributed to its excellent dynamic equilibrium between *H generation and consumption during NO₃RR. Furthermore, the Lewis acid character inherent to TiO₂ accelerates interfacial water supply and boosts proton migration on the catalyst surface by optimizing the hydrogen-bond network and the local distribution of interfacial water molecules, thereby benefitting for the electrocatalytic process. Consequently, the optimized CuAg@TiO₂ achieves a remarkable NO₃RR performance, delivering an NH₃ yield rate of 55.44 mg cm^-2 h^-1 at -0.969 V vs. RHE, significantly superior to that of its single-metal counterparts and also exceeds many current benchmark NO₃RR electrocatalysts. Notably, it also attains a Faraday efficiency (FE) of 98.6% alongside an NH₃ selectivity of 95.3% at -0.569 V vs. RHE, respectively. This work proposes a strategic design principle that guides the engineering of synergistic active sites in nanostructured catalysts toward efficient and selective NH₃ production.