Researchers achieve electrosynthesis of ammonia from NO in pressurized electrolyzer

Electrocatalytic nitric oxide reduction reaction (NORR) offers a promising route for sustainable ammonia (NH₃) synthesis and for removing NO pollutants. However, achieving NH₃ production from NO with ampere-level current density and long-term stability remains a challenge for industrial applications.

One major obstacle is the poor solubility of NO in water combined with the undesirable hydrogen evolution reaction (HER), which limits the efficiency and durability of NH₃ production on an industrial scale.

In a study published in Nature Communications, a research group led by Prof. DENG Dehui, Assoc. Prof. CUI Xiaoju, and Prof. YU Liang from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences developed a sustainable electrosynthesis method for NH₃ from NO, achieving ampere-level current density in a pressurized electrolyzer.

Researchers used an in situ-grown hierarchical porous copper nanowire array (Cu NWA) monolithic electrode to regulate the kinetics and thermodynamics of the NORR. They achieved a NH₃ partial current density of 1007 mA cm^-2, a Faradaic efficiency of 96.1%, and an NH₃ yield rate of 10.5 mmol h^-1 cm^-2, demonstrating great potential for industrial applications.

The high NORR performance was revealed to benefit from the in situ-formed hierarchical porous structure of the Cu NWA electrode. This structure maximized the exposure of Cu active sites, enhancing internal mass transfer. The high-pressure environment within the electrolyzer enhanced NO solvation and external mass transfer, promoting NO adsorption onto the Cu surface. The high NO coverage destabilized the adsorbed NO and weakened hydrogen adsorption, facilitating efficient NO hydrogenation to NH₃ while suppressing the HER.

"Our study provides a new way for the industrial electrosynthesis of ammonia and the efficient catalytic conversion of inert small molecules," said Prof. DENG.