Electrospun zirconia nanofibers for enhancing the electrochemical synthesis of ammonia by artificial nitrogen fixation

Abstract

The electrocatalytic nitrogen reduction reaction (NRR) has been deemed a promising and reliable approach to massively produce ammonia under ambient conditions. A high-efficiency electrocatalyst with an excellent selectivity is highly required to reduce the multiple reaction barriers of N₂ + 3H₂O → 2NH₃ + 1.5O₂. Here, we report electrospun zirconia nanofibers as a non-noble NRR electrocatalyst to convert nitrogen to ammonia. Theoretical calculations predict that the Zr sites with oxygen vacancies are favorable for nitrogen adsorption and reduction. Experimentally, the larger concentration of oxygen defects in such an electrocatalyst allowed achieving a NH₃ formation rate of 9.63 μg h⁻¹ mg_cat.⁻¹ and an optimal faradaic efficiency of 12.1% at −0.7 V vs. the reversible hydrogen electrode in 0.1 M Na₂SO₄.