Issue 16, 2024

Harnessing halogen bond donors for enhanced nitrogen reduction: a case study on metal-free boron nitride single-atom catalysts

Abstract

Developing efficient catalysts for ammonia synthesis is increasingly crucial but remains a formidable challenge due to the lack of robust design criteria, particularly in addressing the activity and selectivity issues, especially in electrochemical nitrogen reduction reactions (NRR). In this study, we systematically investigated the catalytic potential of hexagonal boron nitride (BN) embedded with non-metal (C, Si, P and S) atoms as an electrocatalyst for the nitrogen reduction reaction using density functional theory (DFT) computations. The preference for non-metal-doped BN nanomaterials stems from their ability to suppress hydrogen evolution and their environmentally friendly nature, in contrast to transition metals. Among the designed single-atom catalysts (SACs), Si-doped boron nitride (SiBBN) exhibits a favorable inclination toward activating nitrogen, which is determined by the combination of advantageous molecular orbital coupling and formation of a covalent bond with the N2 molecule. Under thermal conditions, the first protonation step emerges as the rate-determining step (22.66 kcal mol−1) for SiBBN. Conversely, under electrochemical conditions, the final elementary step becomes the potential-determining step (PDS) with 2.38 eV. We explored the impact of the exogenous addition of Lewis acids (alkali metal ions, neutral boron Lewis acids, and halogen bond donors) on modulating the electrochemical NRR activity. Our results highlight the pivotal role of halogen bond donors as catalytic promoters in facilitating electron density transfer through activated N2, establishing a push–pull charge transfer mechanism that populates the distal nitrogen more than the proximal nitrogen. This facilitates the potential requirements for the first reduction step. The synergistic effect of both halogen bonding and hydrogen bonding interactions in the final reduction step was proven to be the main determinant for a significant reduction in the PDS from 2.38 to 0.10 V. Notably, this study unveils the pioneering role of halogen bond donors as promoters for NRR, providing valuable insights into the development of robust metal-free catalysts and promoters in experimental research.

Graphical abstract: Harnessing halogen bond donors for enhanced nitrogen reduction: a case study on metal-free boron nitride single-atom catalysts

Supplementary files

Article information

Article type
Paper
Submitted
07 янв 2024
Accepted
27 мар 2024
First published
27 мар 2024

Phys. Chem. Chem. Phys., 2024,26, 12495-12509

Harnessing halogen bond donors for enhanced nitrogen reduction: a case study on metal-free boron nitride single-atom catalysts

V. S. K. Choutipalli and V. Subramanian, Phys. Chem. Chem. Phys., 2024, 26, 12495 DOI: 10.1039/D4CP00076E

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements