Characterization of Au and Bimetallic PtAu Nanoparticles on PDDA-Graphene Sheets as Electrocatalysts for Formic Acid Oxidation.

Tung-Yuan Yung,Huei-Ming Tzou,Kuan-Syun Wang,Po-Tuan Chen,Ting-Yu Liu,Ling-Kang Liu,Li-Ying Huang,Chi-Yang Chao

doi:10.1186/s11671-015-1071-4

Abstract

Nanocomposite materials of the Au nanoparticles (Au/PDDA-G) and the bimetallic PtAu nanoparticles on poly-(diallyldimethylammonium chloride) (PDDA)-modified graphene sheets (PtAu/PDDA-G) were prepared with hydrothermal method at 90 °C for 24 h. The composite materials Au/PDDA-G and PtAu/PDDA-G were evaluated by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA) for exploring the structural characterization for the electrochemical catalysis. According to TEM results, the diameter of Au and bimetallic PtAu nanoparticles is about 20–50 and 5–10 nm, respectively. X-ray diffraction (XRD) results indicate that both of PtAu and Au nanoparticles exhibit the crystalline plane of (111), (200), (210), and (311). Furthermore, XRD data also show the 2°–3° difference between pristine graphene sheets and the PDDA-modified graphene sheets. For the catalytic activity tests of Au/PDDA-G and PtAu/PDDA-G, the mixture of 0.5 M aqueous H2SO4 and 0.5 M aqueous formic acid was used as model to evaluate the electrochemical characterizations. The catalytic activities of the novel bimetallic PtAu/graphene electrocatalyst would be anticipated to be superior to the previous electrocatalyst of the cubic Pt/graphene.

Highlights

Formic acid and methanol are potential in the conversions between chemical energy and electric energy as the chemical fuels
Researchers have dismissed formic acid as a practical fuel because of the high overpotential evidenced by experiments, indicative that the reaction starting from formic acid appeared to be too difficult
Pt-M alloy and bimetallic core-shell nanoparticles promised for electrocatalytic reactions have been developed [5,6,7], which could enhance the electrocatalytic abilities by high

Summary

Introduction

Formic acid and methanol are potential in the conversions between chemical energy and electric energy as the chemical fuels. The bimetallic Pt-based nanomaterials were introduced as anode catalysts for methanol and formic acid oxidation [1,2,3,4,5,6,7]. An alternative pathway leading to CO intermediate for the methanol or formic acid oxidation results in the poisoning of the active Pt surfaces with covalent CO bonding. To avoid this situation, two ways of improvement are considered usually to enhance the Pt activity with catalytic performance: (1) synthesis of the Pt-M bimetallic electrocatalysts and (2) addition of the carbon materials as support [9,10,11]

Methods

Results

Conclusion