Facile Fabrication of Platinum-Cobalt Alloy Nanoparticles with Enhanced Electrocatalytic Activity for a Methanol Oxidation Reaction

Huihong Huang,Nan Su,Jianbo Zhang,Xiulan Hu,Jiexu Cheng

doi:10.1038/srep45555

Abstract

Decreasing the cost associated with platinum-based catalysts along with improving their catalytic properties is a major challenge for commercial direct methanol fuel cells. In this work, a simple and facile strategy was developed for the more efficient preparation of multi-walled carbon nanotube (MWCNT) -supported Pt/CoPt composite nanoparticles (NPs) via solution plasma sputtering with subsequent thermal annealing. Quite different from general wet synthesis methods, Pt/CoPt composite NPs were directly derived from metal wire electrodes without any additions. The obtained Pt/CoPt/MWCNTs composite catalysts exhibited tremendous improvement in the electro-oxidation of methanol in acidic media with mass activities of 1719 mA mg−1Pt. This value is much higher than that of previous reports of Pt-Co alloy and commercial Pt/C (3.16 times) because of the many active sites and clean surface of the catalysts. The catalysts showed good stability due to the special synergistic effects of the CoPt alloy. Pt/CoPt/MWCNTs can be used as a promising catalyst for direct methanol fuel cells. In addition, this solution plasma sputtering-assisted synthesis method introduces a general and feasible route for the synthesis of binary alloys.

Highlights

Direct methanol fuel cells (DMFCs) have attracted extensive attention as a promising potential sustainable power source due to their clean emissions, high power density and high energy conversion efficiency[1,2,3]
The consumption of platinum and cobalt wires were 10.1 mg and 2.9 mg, respectively, after discharge for 30 min with the experimental parameters of 2 kV, 20 kHz and 2.5 μs. Following this procedure, the above obtained NPs in uniform suspension were mixed with a dispersed aqueous multi-walled carbon nanotube (MWCNT) by ultrasonic treatment to prevent NP aggregation and improve their electrical conductivity
Pt/CoPt-1/ MWCNTs were annealed at 700 °C for 2 h under flowing N2 to obtain Pt/CoPt-2/MWCNTs to obtain a high degree of alloying in the Pt-Co alloy NPs

Summary

Introduction

Direct methanol fuel cells (DMFCs) have attracted extensive attention as a promising potential sustainable power source due to their clean emissions, high power density and high energy conversion efficiency[1,2,3]. The efficient synthesis of high-quality, uniformly dispersed Pt-Co alloy NPs is a promising strategy for developing advanced hybrid catalysts in DMFCs. colloidal method[30,31,32], and chemical vapor deposition (CVD)[16,33,34]. Carbon nanotubes (CNTs) have been used to support bimetallic NPs as a promising electro-catalyst for the MOR, owing to their higher electrical conductivity, higher catalyst loading efficiency, higher stability and higher surface-to-volume ratio compared with carbon black[12,39]. As-obtained Pt/CoPt composite catalysts exhibited excellent electro-catalytic activity and stability for the MOR due to their high dispersion, the high alloying degree and the “clean” surface of the catalysts

Methods

Results

Conclusion