Facile Synthesis of Bimetallic Pt-Ag/Graphene Composite and Its Electro-Photo-Synergistic Catalytic Properties for Methanol Oxidation

Shuhong Xu,Shen Lin,Lingting Ye,Zhongshui Li,Fengling Lei,Yanli Wang

doi:10.3390/catal6090144

Abstract

A Pt-Ag/graphene composite (Pt-Ag/GNs) was synthesized by the facile aqueous solution method, in which Ag+ was first transformed into Ag2O under UV light irradiation, and then Ag2O, Pt2+, and graphene oxide (GO) were simultaneously reduced by formic acid. It was found that Pt-Ag bimetallic nanoparticles were highly dispersed on the surface of graphene, and their size distribution was narrow with an average diameter of 3.3 nm. Electrocatalytic properties of the Pt-Ag/GNs composite were investigated by cyclic voltammograms (CVs), chronoamperometry (CA), CO-stripping voltammograms, and electrochemical impedance spectrum (EIS) techniques. It was shown that the Pt-Ag/GNs composite has much higher catalytic activity and stability for the methanol oxidation reaction (MOR) and better tolerance toward CO poisoning when compared with Pt/GNs and the commercially available Johnson Matthey 20% Pt/C catalyst (Pt/C-JM). Furthermore, the Pt-Ag/GNs composite showed efficient electro-photo-synergistic catalysis for MOR under UV or visible light irradiation. Particularly in the presence of UV irradiation, the Pt-Ag/GNs composite exhibited an ultrahigh mass activity of 1842.4 mA·mg−1, nearly 2.0 times higher than that without light irradiation (838.3 mA·mg−1).

Highlights

Platinum has attracted significant attention as a catalyst for the methanol oxidation reaction (MOR) [1]
Ag has a high degree of free electron mobility and exhibits molecular-like excited-state properties with well-defined absorption and emission features, and its surface plasmon resonance (SPR) effect has a prominent contribution to the enhanced photocatalytic activity [12,13]
The diffraction pattern for the Pt/graphene nanosheets (GNs) catalyst shows the typical peaks of the face centered‐

Summary

Introduction

Platinum has attracted significant attention as a catalyst for the methanol oxidation reaction (MOR) [1]. Binary or ternary Pt-based catalysts containing other transition metals, such as NiAuPt [3], PtRu [4], PtCu [5], FePt [6], PtSn [7], PtCo [8], PtRhNi [9], or PtPd [10] can improve the performance in catalyzing MOR compared with the monometallic Pt catalysts. They can alleviate COads poisoning and expose more Pt active sites, resulting in lower noble metal dosages and lower costs.

Methods

Results

Conclusion