In:
Energy & Environmental Science, Royal Society of Chemistry (RSC), Vol. 15, No. 7 ( 2022), p. 2776-2805
Abstract:
The electrocatalytic N 2 reduction reaction (NRR) offers an alternative to the traditional Haber–Bosch (H–B) process for the synthesis of ammonia (NH 3 ) and has received a surge of interest recently. However, as the prerequisite step for an efficient NRR, the N 2 activation process over an electrocatalyst is rather difficult to be realized under mild conditions due to the thermodynamic stability and chemical inertness of the N 2 molecule, which greatly limits the selectivity and activity of the NRR process, as well as the development of this renewable synthesis route for NH 3 . To date, a variety of electrocatalysts have been developed for effective N 2 activation in the past five years, although the presented activation abilities for N 2 molecules remain unsatisfactory even on the laboratory scale, and the corresponding design concepts/principles are still at the trial-and-error stage. Instead of focusing on labeling and classifying NRR electrocatalysts that have been extensively reviewed elsewhere, we herein present a timely and comprehensive review of emerging strategies to activate the inert N 2 molecule for NH 3 electrosynthesis at the microscopic and macroscopic level on the basis of an in-depth understanding of the physicochemical properties and microelectronic structure of the N 2 molecule. We initially analyze the physicochemical properties and the microelectronic structure of the N 2 molecule from the perspective of molecular orbital theory. On the basis of this, we then emphasize the microscopic electronic effects of electrocatalysts for enhancing N 2 activation at length, typically covering σ-donation, π-backdonation, and σ-donation/π-backdonation effects, along with the design concepts/principles of electrocatalysts. Subsequently, the driving forces of macroscopic external fields (such as light, plasma, etc. ) and the local microenvironment regulation-induced built-in electrostatic fields for assisting N 2 activation are introduced. In addition, the methodologies for studying the N 2 activation process over electrocatalyst surfaces are also presented from theoretical and experimental perspectives. Finally, we look at the future research directions and opportunities for improving N 2 activation and stimulating the practical application of NRR technology, covering electrocatalyst engineering, process intensification, and device architecture.
Type of Medium:
Online Resource
ISSN:
1754-5692
,
1754-5706
Language:
English
Publisher:
Royal Society of Chemistry (RSC)
Publication Date:
2022
detail.hit.zdb_id:
2439879-2
Permalink