MoO3 nanosheets for efficient electrocatalytic N2 fixation to NH3

Abstract

The synthesis of NH₃ heavily depends on the energy-intensive Haber–Bosch process with a large amount of greenhouse gas emission. Electrochemical reduction offers a carbon-neutral process to convert N₂ to NH₃ at ambient conditions, but requires efficient and stable catalysts for the N₂ reduction reaction. Mo-dependent nitrogenases and synthetic molecular complexes have attracted increasing attention for N₂ fixation; however, less attention has been paid to Mo-based nanocatalysts for electrochemical N₂ conversion to NH₃. Herein, we report that MoO₃ nanosheets act as an efficient non-noble-metal catalyst for electrochemical N₂ fixation to NH₃ with excellent selectivity at room temperature and atmospheric pressure. In 0.1 M HCl, this catalyst exhibits remarkable NRR activity with an NH₃ yield of 4.80 × 10⁻¹⁰ mol s⁻¹ cm⁻² (29.43 μg h⁻¹ mg_cat.⁻¹) and a faradaic efficiency of 1.9%. Moreover, this catalyst also shows high electrochemical stability and durability. Density functional theory calculations reveal that the outermost Mo atoms serve as the active sites for effective N₂ adsorption.