Issue 20, 2021

Highly efficient ammonia synthesis at low temperature over a Ru–Co catalyst with dual atomically dispersed active centers

Abstract

The desire for a carbon-free society and the continuously increasing demand for clean energy make it valuable to exploit green ammonia (NH3) synthesis that proceeds via the electrolysis driven Haber–Bosch (eHB) process. The key for successful operation is to develop advanced catalysts that can operate under mild conditions with efficacy. The main bottleneck of NH3 synthesis under mild conditions is the known scaling relation in which the feasibility of N2 dissociative adsorption of a catalyst is inversely related to that of the desorption of surface N-containing intermediate species, which leads to the dilemma that NH3 synthesis could not be catalyzed effectively under mild conditions. The present work offers a new strategy via introducing atomically dispersed Ru onto a single Co atom coordinated with pyrrolic N, which forms RuCo dual single-atom active sites. In this system the d-band centers of Ru and Co were both regulated to decouple the scaling relation. Detailed experimental and theoretical investigations demonstrate that the d-bands of Ru and Co both become narrow, and there is a significant overlapping of t2g and eg orbitals as well as the formation of a nearly uniform Co 3d ligand field, making the electronic structure of the Co atom resemble that of a “free-atom”. The “free-Co-atom” acts as a bridge to facilitate electron transfer from pyrrolic N to surface Ru single atoms, which enables the Ru atom to donate electrons to the antibonding π* orbitals of N2, thus resulting in promoted N2 adsorption and activation. Meanwhile, H2 adsorbs dissociatively on the Co center to form a hydride, which can transfer to the Ru site to cause the hydrogenation of the activated N2 to generate N2Hx (x = 1–4) intermediates. The narrow d-band centers of this RuCo catalyst facilitate desorption of surface *NH3 intermediates even at 50 °C. The cooperativity of the RuCo system decouples the sites for the activation of N2 from those for the desorption of *NH3 and *N2Hx intermediates, giving rise to a favorable pathway for efficient NH3 synthesis under mild conditions.

Graphical abstract: Highly efficient ammonia synthesis at low temperature over a Ru–Co catalyst with dual atomically dispersed active centers

Supplementary files

Article information

Article type
Edge Article
Submitted
16 jan 2021
Accepted
07 apr 2021
First published
07 apr 2021
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2021,12, 7125-7137

Highly efficient ammonia synthesis at low temperature over a Ru–Co catalyst with dual atomically dispersed active centers

X. Peng, H. Liu, Y. Zhang, Z. Huang, L. Yang, Y. Jiang, X. Wang, L. Zheng, C. Chang, C. Au, L. Jiang and J. Li, Chem. Sci., 2021, 12, 7125 DOI: 10.1039/D1SC00304F

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements