Electrochimica Acta, Vol.228, 474-482, 2017
Ascorbic acid assisted bio-synthesis of Pd-Pt nanoflowers with enhanced electrochemical properties.
Bimetallic Pd-Pt nanoflowers (Pd-Pt NFs) of varying sizes (20-60 nm) were synthesized through the concurrent reduction of Pd(NO3)(2) and K2PtCl4 using Cinnamomum camphora (C camphora) leaf extract assisted by ascorbic acid (AA). C.Camphora acted as both a co-reducing agent and a green template in the synthesis protocol providing a fast, simple, green and cost-effective means of producing the Pd-Pt NFs. Characterization techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were used to confirm the Pd-Pt NFs formation. FT-IR analysis showed that biomolecules such as polyphenols and flavonoids were responsible for the reduction while stretching vibration bands from C-H,-C=C-,O-H, and -C-O-O acted as capping agents. The as formed Pd-Pt NFs showed excellent performance and stability in the electro-oxidation of ethanol in alkaline media. Electro-catalytic performance increased with Pt content, while addition of Pd increased stability. The PdPt3 NFs presented the best performance with a mass activity of 1.43 A mg(metal)(-1), 5.72, 4.93, 2.27, 1.27, 11 and 4.6% higher than the Pd, Pt, Pd3Pt, and PdPt NFs, and commercial Pt and Pd-black respectively. However, it was more prone to poisoning, with an I-f/I-r value of 0.78 compared to 1.37 for Pd3Pt NFs. (C) 2017 Elsevier Ltd. All rights reserved.
Keywords:biosynthesis;direct alcohol fuel cells;Pd-Pt nanoflowers;electro-catalyts;ethanol oxidation