A magnetron sputtered Mo3Si thin film: an efficient electrocatalyst for N2 reduction under ambient conditions

Abstract

Industrially, large-scale NH₃ production mainly depends on the Haber–Bosch process, which is accompanied by heavy greenhouse gas emission and serious energy consumption. Electrochemical N₂ reduction is considered a sustainable strategy to solve this problem. Herein, we report for the first time that a Mo₃Si thin film sputtered on graphite paper is a favorable electrocatalyst for NH₃ synthesis under ambient conditions. Electrochemical tests suggest a large NH₃ yield rate of 2 × 10⁻¹⁰ mol s⁻¹ cm⁻² and a high Faraday efficiency of 6.69% at −0.4 V and −0.3 V vs. a reversible hydrogen electrode, respectively, in 0.1 M Na₂SO₄. It also demonstrates the high electrochemical and structural stability of such a catalyst as well as excellent selectivity for NH₃ generation. Density functional theory calculation reveals that the synergy of the metallic conductivity of Mo₃Si and the high chemical activity of the exposed Mo ions benefits the adsorption and activation of N₂, and a further proton–electron transfer reaction to produce NH₃.