Electrosynthesis of NH3 from N2 using nanostructured Bi4Ti3O12 catalyst†

Abstract

The electrocatalytic N₂ fixation provides a carbon-neutral and energy-efficient pathway for producing ammonia effectively under ambient conditions. However, it typically faces significant challenges in achieving a high ammonia yield and FE. This is attributed to the lack of efficient electrocatalysts that can easily activate the strong N₂ triple bond and suppress the competing HER. Metal oxides are widely acknowledged as effective electrocatalysts for nitrogen reduction reaction (NRR) because they can assist in easily activating the triple bond of N₂. Herein, we demonstrate that a mixed metal oxide, Bi₄Ti₃O₁₂, holds potential as a catalyst for electrocatalytic NRR under ambient conditions with an ammonia yield of 27.8 μg h⁻¹ mg_cat⁻¹ and FE of 22% at −0.6 V in 0.1 M HCl. The synergistic effect of the N₂ binding ability of Ti and Bi, coupled with a robust interaction of the Bi 6p band and N 2p orbitals and the low hydrogen adsorption energy of Bi collectively inhibit surface electron accessibility for the HER, thereby facilitating the easy activation of N₂ and results in better electrocatalytic activity and selectivity for NRR.