Cornered silver and silversingle bondplatinum nanodisks: Preparation and promising activity for alkaline oxygen reduction catalysis

Authors:  Chien-Liang Lee, Ciou-Mei Syu, Chun-Han Huang, Hsueh-Ping Chiou, Yi-Ju Chao, Chia-Chen Yang

Abstract:
A simple method for the efficient synthesis of cornered Ag and Ag–Pt nanodisks by using triangular Ag nanoplates as reactants has been developed. The triangular Ag nanoplates are heated and reshaped to spherical nanodisks; in turn, through the introduction of PtCl₄²⁻ ions, the spherical nanodisks undergo sculpturing and a subsequent displacement reaction to form cornered Ag nanodisks and Ag–Pt nanodisks with pores. The selected-area electron diffraction pattern shows that the cornered Ag nanodisks are composed of two basal Ag (1 1 1) planes, thus indicating the occurrence of selective etching on the spherical nanodisks by this method. The analyses provided by X-ray diffraction spectroscopy and line-scanned energy-dispersive spectroscopy confirm the compositions of these cornered nanodisks and the mixed alloy in the Ag–Pt nanodisks. For the investigation of the practical feasibility of the application of the proposed method, these cornered Ag and Ag Pt nanodisks were then used as methanol-tolerant electrocatalysts in the alkaline oxygen reduction reaction (ORR). Electrochemical measurements were performed using an ultrathin-film rotating ring-disk electrode. The two types of nanodisks are found to have high stabilities and improved activities in 1 M NaOH electrolyte. In the electrolyte with free methanol, the mass activities at −0.1V (vs. Ag/AgCl; within kinetic control region) in terms of the currents normalized to Ag mass for the Ag nanodisks and Ag–Pt nanodisks are 6.98 × 10⁻⁴ and 2.01 × 10⁻³ mA g⁻¹, respectively, which are greater than the value of 2.09 × 10⁻⁴ mA μg⁻¹ for Ag nanoparticles. The order in terms of the ORR activity is found to be as follows: cornered Ag–Pt nanodisks > cornered Ag nanodisks >Ag nanoparticles. Additionally, in the presence of methanol, all the cornered nanodisk catalysts experience cathodic currents, indicating that the ORR occurs despite the use of a methanol solution.

Keywords:
Unsaturated-bonding catalyst
Fuel cell
Cathodic catalyst
Pt Nanoprism

Published in: Applied Catalysis B: Environmental (Volumes 132–133, Pages 1-552, 27 March 2013)

Publisher: Elsevier  

ISSN Information: 0926-3373

Cornered silver and silversingle bondplatinum nanodisks: Preparation and promising activity for alkaline oxygen reduction catalysis

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