Enhanced electrocatalytic nitrate reduction to ammonia using plasma‐induced oxygen vacancies in CoTiO3 − x nanofiber

Abstract

Abstract Electrochemical nitrate (NO3−) reduction is a green and economic route for ammonia (NH3) synthesis. However, this conversion suffers from low NH3 selectivity due to strong competition from other NO3− reduction pathways. Here, we report that a plasma‐induced defective CoTiO3 − x nanofiber with oxygen vacancies acts as an efficient electrocatalyst for NO3− reduction to NH3. In 0.1 M NaOH solution containing 0.1 M NO3−, it is capable of achieving a remarkable NH3 yield of 30.4 mg h–1 mgcat.–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‐NO3− battery using CoTiO3 − x as the cathode catalyst offers a peak power density of 5.04 mW cm−2 and a large NH3 yield of 3.08 mg h−1 mgcat.−1. The catalytic mechanism is further discussed by density functional theory calculations.

Keywords

• CoTiO3 − x nanofiber
• electrocatalysis
• NH3 synthesis
• NO3– reduction reaction
• oxygen vacancies