Porous LaFeO3 nanofiber with oxygen vacancies as an efficient electrocatalyst for N2 conversion to NH3 under ambient conditions

Abstract

Electrocatalytic N 2 reduction to NH 3 under ambient conditions is an eco-friendly and sustainable alternative to the traditional Haber-Bosch process. However, inhibited by the high activation barrier of N 2 , this process needs efficient electrocatalysts to adsorb and activate the N 2 , enabling the N 2 reduction reaction (NRR). Herein, we report that porous LaFeO 3 nanofiber with oxygen vacancies acts as an efficient NRR electrocatalyst with abundant active sites to enhance the adsorption and activation of N 2 . When tested in 0.1 M HCl, such electrocatalyst achieves a high Faradaic efficiency of 8.77% and a large NH 3 yield rate of 18.59 µg h –1 mg cat. –1 at −0.55 V versus reversible hydrogen electrode. This catalyst also shows high long-term electrochemical stability and excellent selectivity for NH 3 formation. Density functional theory calculations reveal that, by introducing oxygen vacancy on LaFeO 3 , the subsurface metallic ions are exposed with newly localized electronic states near the Fermi level, which facilitates the adsorption and activation of N 2 molecules as well as the subsequent hydrogenation reactions. As a N 2 reduction reaction electrocatalyst, porous LaFeO 3 nanofiber with oxygen vacancies (Vo-LaFeO 3 NF) achieves a large NH 3 yield of 18.59 μg h −1 mg cat. −1 and a high Faradic efficiency of 8.77% at –0.55 V vs. RHE in 0.1 M HCl.