Issue 4, 2023

Unveiling the particle size effect and surface reactivity of Pt/C nanoparticles for ammonia electrooxidation using in situ infrared spectroscopy

Abstract

The ammonia electrooxidation reaction (AmER) has attracted considerable attention due to its potential for hydrogen storage and transportation, as well as its possible application in direct ammonia fuel cells. In the present work, we studied ammonia electrooxidation on carbon-supported Pt/C nanoparticles (NPs) of four average sizes of 1.3, 2.2, 2.8, and 4.2 nm. Carbon-supported Pt NPs with a 20 wt% metal loading were synthesized using the polyol method, and the control of the synthesis solution pH allowed the formation of Pt NPs of different average sizes, which was confirmed by TEM. The onset potential was more negative for the smallest nanoparticles (1.3 nm) compared to those for the larger ones. Pt/C with a mean particle size of 2.2 nm showed better stability while exhibiting comparable activity to the 1.3 nm particles. As revealed by in situ polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), the oxidation products included N–H species, azide ions, and nitrate and nitrite compounds. The N–H stretching peak was observed at about 2800 cm−1 on the Pt surface and in the bulk of the electrolyte. However, the intensity of peaks corresponding to the reaction products was different on the surface of Pt and in the bulk of the electrolyte. NO2 was mostly observed in the bulk of the electrolyte. In contrast, NO3 was present on the Pt surface. PM-IRRAS demonstrated that the particle size affected the catalytic activity of Pt/C NPs but not their selectivity. In addition, the PM-IRRAS technique allowed, for the first time, distinguishing both symmetric and asymmetric N–O bonds that were not observed previously using IR spectroscopy during ammonia electrooxidation.

Keywords: Ammonia electrooxidation; Carbon-supported Pt nanoparticle; Catalyst; PM-IRRAS; In situ infrared spectroscopy.

Graphical abstract: Unveiling the particle size effect and surface reactivity of Pt/C nanoparticles for ammonia electrooxidation using in situ infrared spectroscopy

Supplementary files

Article information

Article type
Paper
Submitted
13 jun 2023
Accepted
02 sep 2023
First published
08 sep 2023
This article is Open Access
Creative Commons BY-NC license

Ind. Chem. Mater., 2023,1, 542-552

Unveiling the particle size effect and surface reactivity of Pt/C nanoparticles for ammonia electrooxidation using in situ infrared spectroscopy

N. Aligholizadeh K, A. R. N, E. A. Monyoncho and E. A. Baranova, Ind. Chem. Mater., 2023, 1, 542 DOI: 10.1039/D3IM00063J

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. You can use material from this article in other publications, without requesting further permission from the RSC, provided that the correct acknowledgement is given and it is not used for commercial purposes.

To request permission to reproduce material from this article in a commercial publication, 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 commercial 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