Nitrogenase-Inspired Atomically Dispersed Fe–S–C Linkages for Improved Electrochemical Reduction of Dinitrogen to Ammonia

Abstract

The electrochemical nitrogen reduction reaction (NRR) provides a sustainable alternative to the Haber−Bosch process for ammonia (NH 3 ) production. Transition metal catalysts have poor NRR performance due to the highly competitive hydrogen evolution reaction and the scaling relation between inert dinitrogen (N 2 ) and other reaction intermediates. Owing to the enhanced active sites and the anomalous quantum size effect, single-atom catalysts (SACs) have been proven to be effective in overcoming these limitations. Inspired by our understanding of metal− sulfur (M−S) linkages in the nitrogenase enzyme, we have modulated the electronic structure of iron by tethering to sulfur in a mesoporous carbon matrix. Theoretical calculations identified enhanced electron transfer and flexible coordination as important features of Fe−S−C linkages responsible for the improved NRR performance, which is achieved due to enhanced N 2 interaction with localized charge density sites formed by Fe−S−C linkages. A high faradaic efficiency (6.1 ± 0.9%) with an improved rate of NH 3 formation (8.8 ± 1.3 μg h −1 mg −1 ) is obtained on the best-performing sample at −0.1 V versus RHE. Our work reveals the importance of M−S linkages for improved NRR performance and provides a strategy for the rational catalyst design.

Regulating the spin order of transition metal embedded-MXenes for boosting electrocatalytic nitrogen reduction to ammonia

“…Sulfur was chosen as the capping functional group of clean Mo 2 C to simulate the Mo-S-Fe structure in biological nitrogen xation enzymes. 59,60 The passivated Mo 2 C surface that introduces iron (Fe) atoms and the sulfur (S) capping functional group of MXenes has been synthesized experimentally. 61 There are three functional group adsorption sites on the surface of Mo 2 C, which can be classied into the top site, hcp site and fcc site according to the coordination environment, 62 as shown in Fig.…”

Anchoring Mo Single-Atom Sites on B/N Codoped Porous Carbon Nanotubes for Electrochemical Reduction of N2 to NH3

“…As an essential component of chemical products, ammonia (NH 3 ) is currently one of the most important raw materials for fertilizers and has the potential to become a major form of transportable renewable energy in the future. − However, the current industrial production method combining the Haber–Bosch process and steam hydrocarbon reforming has the disadvantages of high energy consumption, high pollution, need for nonrenewable energy, high temperature (about 600 °C), and pressure (about 30 MPa), which all cause obstacles to the development of future ammonia recycling economy. − Therefore, the direct use of renewable electricity to convert N 2 to NH 3 [electrochemical N 2 reduction reaction (ENRR)] in small-scale electrolytic cells using H 2 O and N 2 as feedstock is a better option, which also facilitates small-scale and distributed production. − However, because of the presence of competing hydrogen evolution reactions (HER), relatively weak N 2 adsorption, and slow reaction kinetics, the rate and selectivity of ENRR are inhibited. , Therefore, the ENRR process demands high-performance electrocatalysts to catalyze the complex six-electron reduction of N 2 while preventing the occurrence of competitive HER. , …”

Defective 2D silicon phosphide monolayers for the nitrogen reduction reaction: a DFT study

“…Within the framework of 2D SiP, the electronegativity of Si is just a little bit lower than that of P (2.1), thus localized sites with high electron density will appear for N 2 adsorption and activation. 46 In this work, we employed density functional theory (DFT) calculations to investigate the possibility of the ENRR on 2D SiP. We found that pristine 2D SiP monolayers cannot activate inert N 2 due to surface phosphorus (P) atom covering (see Fig.…”