Synthesis and characterization of AgPd alloy coatings as beneficial catalysts for low temperature fuel cells application. (1st June 2019)

• Record Type: Journal Article
• Authors: Elezović, N.R.; Lovic, J.D.; Jović, B.M.; Zabinski, P.; Włoch, Grzegorz; Jović, V.D.
• Is Part Of: Electrochimica acta. Volume 307(2019)
• Page Start: 360
• Page End: 368
• Publication Date: 2019-06-01
• Subjects: AgPd alloy -- Electrodeposition -- SEM-EDS -- XPS -- Oxygen reduction; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2019.03.177
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: The Ag, Pd and AgPd alloys of different morphologies and compositions were electrodeposited onto Au and glassy carbon (GC) disc electrodes from the solution containing 0.001 M PdCl2 + 0.04 M AgCl + 0.1 M HCl + 12 M LiCl under the conditions of non-stationary (RPM = 0, samples AgPd1 and AgPd2) and convective diffusion (RPM = 1000, sample AgPd3). Electrodeposited alloy layers were characterized by the scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS). Oxygen reduction reaction (ORR) was investigated on all coatings in 0.1 M NaOH solution saturated with oxygen. The j - E curves for the ORR were recorded by two procedures: (1) samples were cycled with 5 mV s −1 from open circuit potential (OCP) to −0.8 V for Ag and AgPd alloys (or −0.6 V for pure Pd) and back; (2) samples were cycled with 5 mV s −1 from open circuit potential to 0.45 V (formation of Ag2 O, in the case of Pd formation of PdO and PdO2 ), from 0.45 V to −0.60 V and back to the OCP. Significant catalytic activity for the Ag and AgPd alloys was detected after cycling electrodes in the potential region of Ag2 O formation and reduction. Increase of the catalytic activity for AgPd alloys was, for the first time in the literature, ascribed to the presence of a certain amount of Ag2 O which could not be completely reduced during the reverse sweep from 0.45 V to −0.6 V. Catalytic activity of AgPd alloys was found to be closely related to the amount of non-reduced Ag2 O (most probably in the form of Ag-hydroxide). In the absence of such treatment, the catalytic activity for the ORR on electrodeposited Ag and AgPd alloy coatings was not detected.