Methods for nitrogen activation by reduction and oxidation

Abstract

The industrial Haber-Bosch process to produce ammonia (NH3) from dinitrogen (N2) is crucial for modern society. However, N2 activation is inherently challenging and the Haber-Bosch process has significant drawbacks, as it is highly energy intensive, not sustainable due to substantial CO2 emissions primarily from the generation of H2 and requires large-centralized facilities. New strategies of sustainable N2 activation, such as low-temperature thermochemical catalysis and (photo)electrocatalysis, have been pursued, but progress has been hindered by the lack of rigor and reproducibility in the collection and analysis of results.In this Primer, we provide a holistic step-by-step protocol, applicable to all nitrogen-transformation reactions, focused on verifying genuine N2 activation by accounting for all contamination sources. We compare state-of-the-art results from different catalytic reactions following the protocol's framework, and discuss necessary reporting metrics and ways to interpret both experimental and density functional theory results. This Primer covers various common pitfalls in the field, best practices to improve reproducibility and cost-efficient methods to carry out rigorous experimentation. The future of nitrogen catalysis will require an increase in rigorous experimentation and standardization to prevent false positives from appearing in the literature, which can enable advancing towards practical technologies for the activation of N2.

Dual‐Metal Atom Electrocatalysts: Theory, Synthesis, Characterization, and Applications

“…[ 199,200 ] To face the challenge of producing such a vastly utilized chemical like NH 3 via a less energy‐intensive approach, electrochemical N 2 fixation (or nitrogen reduction reaction, N 2 reduction) has emerged as a suitable alternative. [ 201,202 ]…”

“…[199,200] To face the challenge of producing such a vastly utilized chemical like NH 3 via a less energy-intensive approach, electrochemical N 2 fixation (or nitrogen reduction reaction, N 2 reduction) has emerged as a suitable alternative. [201,202] 2.5.1. Theory N 2 reduction to NH 3 occurs in nature on the nitrogenase enzyme, with a Mo-Fe-S cofactor consisting of two Fe atoms at the catalytic center.…”

Quantitative Operando Detection of Electro Synthesized Ammonia Using Mass Spectrometry

“…The electrosynthesis of ammonia by reduction of molecular nitrogen provides an ambient condition, electricity‐driven alternative to the carbon intensive Haber‐Bosch process [1–4] . Using molecular nitrogen as the educt for electrochemical ammonia synthesis requires selective reductive splitting of the strong nitrogen triple bond, which makes it one of the most challenging catalytic reactions.…”

“…The electrosynthesis of ammonia by reduction of molecular nitrogen provides an ambient condition, electricity-driven alternative to the carbon intensive Haber-Bosch process. [1][2][3][4] Using molecular nitrogen as the educt for electrochemical ammonia synthesis requires selective reductive splitting of the strong nitrogen triple bond, which makes it one of the most challenging catalytic reactions. Nonetheless, when non-aqueous electrolytes are used to minimize proton activity in the electrolyte, faradaic efficiencies towards ammonia of up to 35 % can be achieved at meaningful rates and at ambient conditions.…”

Impact of the dopant-induced ensemble structure of hetero-double atom catalysts in electrochemical NH3 production

“…Group VIII elements (Fe, Ru and Os) have been known to have excellent activity in electrochemical NH 3 production. [17][18][19][20][21][22] In addition, the catalyst research has been expanded to noble metals (e.g. Rh, Pd, Au, Ru, Pt and their oxides, nitrides, and sulphides), non-noble metals (e.g.…”