Three-Phase Electrolysis by Gold Nanoparticle on Hydrophobic Interface for Enhanced Electrochemical Nitrogen...

Electrochemical nitrogen reduction reaction (NRR) provides a facile and sustainable strategy to produce ammonia (NH₃) at ambient conditions. However, the low NH₃ yield and Faradaic efficiency (FE) are still the main challenges due to the competitive hydrogen evolution reaction (HER). Herein, a three-phase electrocatalyst through in situ fabrication of Au nanoparticles (NPs) located on hydrophobic carbon fiber paper (Au/o-CFP) is designed. The hydrophobic CFP surface facilitates efficient three-phase contact points (TPCPs) for N₂ (gas), electrolyte (liquid), and Au NPs (solid). Thus, concentrated N₂ molecules can contact the electrocatalyst surface directly, inhibiting the HER since the lowered proton concentration and overall enhancing NRR. The three-phase Au/o-CFP electrocatalyst presents an excellent NRR performance with high NH₃ yield rate of 40.6 µg h^-1 mg^-1 at -0.30 V and great FE of 31.3% at -0.10 V versus RHE (0.1 m Na₂SO₄). The N₂-bubble contact angle result and cyclic voltammetry analysis confirm that the hydrophobic interface has a relatively strong interaction with N₂ bubble for enhanced NRR and weak electrocatalytic activity for HER. Significantly, the three-phase Au/o-CFP exhibits excellent stability with a negligible fluctuation of NH₃ yield and FE in seven-cycle test. This work provides a new strategy for improving NRR and simultaneously inhibiting HER.