AgPt hollow nanodendrites based on N doping graphene quantum dots for enhanced methanol electrooxidation

Abstract

Direct methanol fuel cells (DMFCs) require high-performance electrocatalysts for utilization at the commercial scale. In this paper, a novel, high-efficiency electrocatalyst composed of silver-platinum hollow nanodendrites based on N doping graphene quantum dots (N-GQDs/AgPt HNDs), which were synthesized via an easy wet chemical method, for the methanol oxidation reaction (MOR) is demonstrated. The photomediated Ag/N-GQDs nanoparticles (Ag/N-GQDs NPs) were firstly prepared under the condition of visible light illumination (the central wavelength is 589 nm), and then galvanic replacement reaction occurred between PtCl62- and Ag nanoparticles to obtain the final product. The morphology of the catalyst exhibits a uniform hollow structure by transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscope (EDX). The effects of the different mole ratio of Ag/Pt on the catalytic activity have been studied by cyclic voltammetry (CV) and chronoamperometry (CA). Under the optimal conditions, N-GQDs/AgPt HNDs show the excellent electrocatalytic activity of 2207.6 mA mgPt−1 towards MOR, which is about 21-fold higher than that of the commercial Pt/C. Interestingly, the photomediated Ag/N-GQDs NPs also caused the N-GQDs/AgPt HNDs catalysts to display a 1.7-fold enhancement in catalytic activity compared to that of the untreated Ag/N-GQDs NPs. Moreover, the CO tolerance and stability of the catalysts for MOR are also greatly improved. The present approach would provide an environment-friendly and valuable way to prepare multi-component catalysts with hollow nanostructures.