Electrochemical Synthesis of Nitric Acid from Nitrogen Oxidation

Abstract

Nitric acid is widely applied in agriculture and industry. The present manufacturing process via a combination of the Haber–Bosch process and the Ostwald oxidation process is accompanied by massive energy consumption and greenhouse gas emissions. The direct electrocatalytic nitrogen oxidation reaction (NOR) to nitric acid is a promising alternative, especially when it is driven by renewable energy sources. The standardization of performance evaluation is the prerequisite for the design and synthesis of efficient electrocatalysts for NOR. In this context, this Minireview first discusses the history of the development of HNO3 manufacturing and the possible reaction mechanisms for electrocatalytic NOR. Then, a strict protocol for electrochemical NOR experiments is recommended. Finally, general research targets associated with techno‐economic analysis, challenges, and prospects for NOR are summarized for future studies.

Catalytic Kinetics Regulation for Enhanced Electrochemical Nitrogen Oxidation by Ru‐Nanoclusters‐Coupled Mn3O4 Catalysts Decorated with Atomically Dispersed Ru Atoms

“…The typical 15 NO 3 − signal at 376.6 ppm is observed in the 15 N-NMR spectra of the electrolyte after electrolysis with the Ru-Mn 3 O 4 catalyst (Figure 3G). Mass spectrometry results show that in the 15 N 2 -saturated electrolyte, the molecular weight of 15 NO 3 − was 62.9884, whereas that of 14 NO 3 − in the 14 N 2 -saturated electrolyte was 61.9899 (Figure S42, Supporting Information). The nitrate yield was also quantified with by 15 N-NMR calibration method (Figure S43, Supporting Information).…”

“…After the first work by Zhang et al, [13,14] the electrochemical N 2 oxidation reaction (NOR), using water and N 2 in the atmosphere (78%), has been demonstrated as a sustainable and promising approach for nitric production. [14][15][16][17][18][19][20][21] Electrochemical NOR is an endothermic and entropy-reducing process, [22,23] involving activation of N 2 , adsorption of OH (*OH), and multielectron transfer at "gas-liquid-solid" three-phase interface. This process is hindered by the slow cleavage of the N≡N bond owing to its high bond energy (941 kJ mol −1 ) and insurmountable first-bond dissociation energy (410 kJ mol −1 ).…”

“…In previous studies, OER-inactive catalysts and carriers were served to restrain competitive OER, and gained reasonable performance. [13][14][15][16][17][18][19][20][21] However, simply suppressing OER would reduce the activation of N 2 , the supply of *OH and sacrifice the inherently low activity towards NOR, insufficient to obtain satisfactory performance. Besides, on count of the obvious difference in dynamics between OER and NOR, electron transfer also largely affect the catalytic selectivity.…”

Recent advances in nanostructured heterogeneous catalysts for N-cycle electrocatalysis

“…−1 and an FE of 11.34% on Pd-decorated Mxene nanosheets (Pd-MX) in 0.01 M Na2SO4 electrolyte. We would recommend that a recent good review for the readers is the paper by Zhang' group [55], including possible reaction mechanisms and challenges in N2 oxidation electrochemistry. The development of such multicomponent catalysts (noble metals + compounds, such as oxides) appears to be an effective method of increasing NOR catalytic activity.…”

Electrocatalytic Oxidation of Dinitrogen to Nitric Acid via Direct Ten–Electron Transfer Using Manganese Phthalocyanine

“…Electrocatalytic dinitrogen oxidation reaction (N 2 OR) using electrocatalyst under ambient conditions is an optimistically promising alternative to develop sustainable nitrate product using various heterogeneous catalysts such as Ru/TiO 2 , Pd-MXene, ZnFe x Co 2-x O 4 , Fe-SnO 2 , Nb 2 O 5-x , Pd-s PNSs, etc. [4][5][6][7][8][9][10][11][12][13][14] . Electrocatalytic N 2 oxidation processes follow a two-step pathway.…”