Deciphering Nickel-catalyzed Electrochemical Ammonia Synthesis from Nitric Oxide

Abstract

Electrochemical conversion of nitric oxide (NO) to ammonia (NH3) is a highly attractive route to achieve artificial nitrogen fixation and rebalance the global nitrogen-circle. Yet today’s poor mechanistic understanding and unsatisfied selectivity towards NH3 curtails NOR ecologic prospects. Here, we screened a library of transition metals as electrocatalysts, in which non-noble Ni outperformed others at the top of a volcano-shaped plot. To further elucidate the active motifs, we rationally designed and fabricated five single-crystal Ni foils with various surface orientations as electrocatalysts, and observed higher conversion efficiencies on high-index facets. In particular, Ni(210) demonstrates a unique selectivity towards NH3 with a yield rate nearly two-folds higher than those of low-index facets. Under the guidance of density functional theory (DFT) calculation, the energy required for key intermediates switching from hollow to bridge sites in the rate-determining hydrogenation step, was established as a descriptor for the capability towards NH3 production. Our work guides the rational design of NOR electrocatalysts, and more importantly, establishes a paradigm to understand the structure-function correlation in catalysis.

Selective Electrocatalytic Conversion of Nitric Oxide to High Value‐Added Chemicals

“…[28] Compared to the SCR method, electrocatalytic technology can selectively convert NO into a series of high-value nitrogen-containing chemicals, such as NH 3 , nitrate (NO 3 − ), hydroxylamine (NH 2 OH), and hydrazine (N 2 H 4 ) under mild conditions. [29,30] Furthermore, when NO is co-electrolyzed with specific carbonaceous molecules, some higher-value chemicals with C─N bonds (e.g., urea, oximes, amino acids, amines, and amides) can be precisely synthesized. [31] At present, many studies focus on the electroreduction of NO 3 − and nitrite (NO 2 − ), which are major pollutants of groundwater, but it is unclear whether this approach is economically feasible in view of the fact that the sources are generally highly diluted.…”

Optimizing Intermediate Adsorption over PdM (M=Fe, Co, Ni, Cu) Bimetallene for Boosted Nitrate Electroreduction to Ammonia

“…[4][5] Such a strategy is high energy-consuming and will cause excessive emission of carbon dioxide, so researchers are continuously seeking for its substitutes. [6][7][8] In recent years, the use of nitrate which is widely spread in nature for ammonia synthesis has been considered a green alternative to traditional ammonia synthesis process. [9][10][11][12] Electroreduction of nitrate to high value-added ammonia (NO 3 RR) is not only an effective way to solve nitrate pollution, but also an optimal strategy for low-temperature ammonia synthesis.…”

Optimizing Intermediate Adsorption over PdM (M=Fe, Co, Ni, Cu) Bimetallene for Boosted Nitrate Electroreduction to Ammonia

“…[4][5] Such a strategy is high energy-consuming and will cause excessive emission of carbon dioxide, so researchers are continuously seeking for its substitutes. [6][7][8] In recent years, the use of nitrate which is widely spread in nature for ammonia synthesis has been considered a green alternative to traditional ammonia synthesis process. [9][10][11][12] Electroreduction of nitrate to high value-added ammonia (NO 3 RR) is not only an effective way to solve nitrate pollution, but also an optimal strategy for low-temperature ammonia synthesis.…”