Durable Electrocatalytic Reduction of Nitrate to Ammonia over Defective Pseudobrookite Fe2TiO5 Nanofibers with Abundant Oxygen Vacancies.

We propose the pseudobrookite Fe2TiO5 nanofiber with abundant oxygen vacancies as a new electrocatalyst to ambiently reduce nitrate to ammonia. Such catalyst achieves a large NH3 yield of 0.73 mmol h-1 mg-1cat. and a high Faradaic Efficiency (FE) of 87.6% in phosphate buffer saline solution with 0.1M NaNO3, which is lifted to 1.36 mmol h-1 mg-1cat. and 96.06% at -0.9 V vs. RHE for nitrite conversion to ammonia in 0.1M NaNO2. It also shows excellent electrochemical durability and structural stability. Theoretical calculation reveals the enhanced conductivity of this catalyst and an extremely low free energy of -0.28 eV for nitrate adsorption at the presence of vacant oxygen.