Promoting methanol-oxidation-reaction by loading PtNi nano-catalysts on natural graphitic-nano-carbon

Abstract

Nano-PtNi (atomic molar ratio Pt/Ni = 1/1) was directly grown, with a one-pot wet-chemical synthesis method, on a novel “natural graphitic-nano-carbon” (NC) for catalyzing the methanol-oxidation-reaction (MOR) in direct methanol fuel cells (DMFC). Comparative examination of PtNi/NC, nano-PtNi grown on commercial conductive carbon black, nano-PtNi with no carrier, and the common “commercial Pt/C” bench-mark, plus those relevant prior arts in the literature, show the excellence of PtNi/NC in mass activity, specific activity and onset potential for MOR. In addition, the morphologic, electronic structures and elemental analysis of these catalysts revealed by electron microscopy, X-ray diffraction, Raman spectrometer, X-ray photoelectron spectroscopy, inductively coupled plasma mass spectrometry and ultraviolet photoemission spectroscopy scientifically explain the observed superiority of PtNi/NC and the critical catalysis-mechanisms. In brief, NC has a high defect density to facilitate monodisperse growth of nano-PtNi with little particle-aggregation, and has a work-function lower than common graphite carbon to maintain PtNi sufficiently electron-rich and thereby MOR-active. Further, NC is produced by selecting a highly conductive coal and wet-comminuting it to less than 100 nm with little environmental load; as such, exploiting NC in DMFC well supports the green-energy mission of DMFC.