Enhanced electrocatalytic nitrate reduction to ammonia using plasma‐induced oxygen vacancies in CoTiO 3 − x nanofiber

Electrochemical nitrate (NO 3 − ) reduction is a green and economic route for ammonia (NH 3 ) synthesis. However, this conversion suffers from low NH 3 selectivity due to strong competition from other NO 3 − reduction pathways. Here, we report that a plasma‐induced defective CoTiO 3 − x nanofiber with oxygen vacancies acts as an efficient electrocatalyst for NO 3 − reduction to NH 3 . In 0.1 M NaOH solution containing 0.1 M NO 3 − , it is capable of achieving a remarkable NH 3 yield of 30.4 mg h –1 mg cat. –1 and a high Faradaic efficiency of 92.6%. The catalyst also shows strong electrochemical stability for a 20‐h electrolysis test. Additionally, a Zn‐NO 3 − battery using CoTiO 3 − x as the cathode catalyst offers a peak power density of 5.04 mW cm −2 and a large NH 3 yield of 3.08 mg h −1 mg cat. −1 . The catalytic mechanism is further discussed by density functional theory calculations.