Highly efficient electrochemical ammonia synthesis using superhydrophobic nanoporous silver

Abstract

Electrochemical nitrogen reduction reaction (ENRR) under ambient conditions offers a greatly promising alternative to the highly-polluting Haber–Bosch process for the production of ammonia. However, due to their unsatisfactory catalytic efficiency, and fussy and costly fabrication process, noble metal-based electrocatalysts can hardly promote the ammonia yield rate for industrial application efficiently. Herein, nanoporous silver structures with a superhydrophobic surface are fabricated via a simple approach. The porous network can afford more active catalytic sites and accessible channels for reactant species. Besides, the hydrophobic surface is achieved by functionalizing with 1H,1H,2H,2H-perfluorodecanethiol (PFDT) on the ligament surface and can weaken the absorbability of H on the catalyst surface, thereby suppressing the occurrence of hydrogen evolution reaction and enhancing ENRR. Hence, superhydrophobic nanoporous silver (SHNPS) displays a superior ammonia faradaic efficiency of (31.1 ± 1.0)% and high ammonia yield of (33.5 ± 1.7) μg h⁻¹ cm⁻², outperforming the ENRR performance of solid silver nanoparticles and hydrophilic nanoporous silver (NPS). Moreover, our catalyst structure also exhibits high electrochemical stability and excellent selectivity. Notably, the design of a hydrophobic nanoporous catalyst provides a valuable practical strategy for ENRR and other gas-relevant electrochemical reactions.