Three Dimensional Porous Graphene/PtPd Bimetallic Hybrids as High-performance Electrocatalyst for Methanol Oxidation

Abstract

The development of fuel cells is highly dependent on the exploration of the efficient electrocatalyst. However, up to now, constructing high-quality hybrids with large electrochemical surface area (ECSA) through a facile method has remained a great challenge. In this paper, a novel approach for producing three dimensional porous graphene/PtPd bimetallic hybrids was developed by combining the solvothermal strategy with the ice template technique. First, a simple solvothermal route were employed for preparing PtPd bimetallic nanoparticle supported on graphene (PPG) hybrids by simultaneously forming bimetallic nanoparticles and reducing graphene oxide (GO). Then, three dimensional porous graphene/PtPd bimetallic hybrids are obtained via the ice templation of an aqueous suspension comprised of the PPG and phthalic acid diethylene glycol diacrylate (PDDA). The as-prepared 3D PPG were characterized by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray diffraction XRD, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and electrochemical technique. It is interesting to find that the loading of PtPd bimetallic nanoparticles on the surface of graphene could be controlled by simply changing the initial weight ratio of the precursors. Furthermore, the hydrophilicability of PDDA plays an important role on the fabrication of 3D porous graphene/PtPd bimetallic hybrids. Most importantly, this special morphology endows the 3D PPG hybrids with larger ECSA and more catalytic sites compared with the PPG and commercial E-TEK Pt/C catalysts, and thus leads to much higher catalytic activity towards methanol oxidation reaction. The details are shown as follows. (a) The ECSA value of the as-prepared 3D PPG hybrids is tested to be 98.7 m(2).g(-1), while the ECSA values of PPG and E-TEK Pt/C catalysts are tested to be 61.3 and 46.5 m(2).g(-1), respectively. (b) The mass current density for methanol oxidation in 3D PPG hybrids is higher than those of PPG and E-TEK Pt/C catalysts and the corresponding potential on 3D PPG hybrids is much lower than that on PPG and E-TEK Pt/C catalysts at a given oxidation current density. (c) The as-prepared 3D PPG hybrids catalyst exhibits greater poisoning tolerance than the PPG and E-TEK Pt/C catalysts during methanol oxidation. All results reveal that these 3D PPG hybrids can provide a new and versatile platform for the development of high-performance electrocatalyst for methanol oxidation.