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Title: Development of core-shell Rh@Pt and Rh@Ir nanoparticle thin film using atomic layer deposition for HER electrocatalysis applications
Authors: Zou, Yiming
Goei, Ronn
Ong, Su-Ann
Ong, Amanda Jiamin
Huang, Jingfeng
Tok, Alfred Iing Yoong
Keywords: Engineering::Materials::Nanostructured materials
Issue Date: 2022
Source: Zou, Y., Goei, R., Ong, S., Ong, A. J., Huang, J. & Tok, A. I. Y. (2022). Development of core-shell Rh@Pt and Rh@Ir nanoparticle thin film using atomic layer deposition for HER electrocatalysis applications. Processes, 10(5), 1008-.
Project: SERC A1983c0032 
Journal: Processes 
Abstract: The efficiency of hydrogen gas generation via electrochemical water splitting has been mostly limited by the availability of electrocatalyst materials that require lower overpotentials during the redox reaction. Noble metals have been used extensively as electrocatalysts due to their high activity and low overpotentials. However, the use of single noble metal electrocatalyst is limited due to atomic aggregation caused by its inherent high surface energy, which results in poor structural stability, and, hence, poor electrocatalytic performance and long-term stability. In addition, using noble metals as electrocatalysts also causes the cost to be unnecessarily high. These limitations in noble metal electrocatalysts could be enhanced by combining two noble metals in a core-shell structure (e.g., Rh@Ir) as a thin film over a base substrate. This could significantly enhance electrocatalytic activity due to the following: (1) the modification of the electronic structure, which increases electrical conductivity; (2) the optimization of the adsorption energy; and (3) the introduction of new active sites in the core-shell noble metal structure. The current state-of-the-art employs physical vapor deposition (PVD) or other deposition techniques to fabricate core-shell noble metals on flat 2D substrates. This method does not allow 3D substrates with high surface areas to be used. In the present work, atomic layer deposition (ALD) was used to fabricate nanoparticle thin films of Rh@Ir and Rh@Pt in a core-shell structure on glassy carbon electrodes. ALD enables the fabrication of nanoparticle thin film on three-dimensional substrates (a 2D functional film on a 3D substrate), resulting in a significantly increased surface area for a catalytic reaction to take place; hence, improving the performance of electrocatalysis. The Rh@Pt (with an overpotential of 139 mV and a Tafel slope of 84.8 mV/dec) and Rh@Ir (with an overpotential of 169 mV and a Tafel slope of 112 mV/dec) core-shell electrocatalyst exhibited a better electrocatalytic performances compared to the single metal Rh electrocatalyst (with an overpotential of 300 mV and a Tafel slope of 190 mV/dec). These represented a 54% and a 44% improvement in performance, respectively, illustrating the advantages of core-shell thin film nanostructures in enhancing the catalytic performance of an electrocatalyst. Both electrocatalysts also exhibited good long-term stability in the harsh acidic electrolyte conditions when subjected to chronopotentiometry studies.
ISSN: 2227-9717
DOI: 10.3390/pr10051008
Schools: School of Materials Science and Engineering 
Rights: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// 4.0/).
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:MSE Journal Articles

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