Carbon-riveted Pt catalyst supported on nanocapsule MWCNTs–Al2O3 with ultrahigh stability for high-temperature proton exchange membrane fuel cells

Abstract

Pt catalyst supported on nanocapsule MWCNTs–Al₂O₃ (multi-walled carbon nanotubes, MWCNTs) catalyst has been prepared by microwave-assisted polyol process (MAPP). The results of electrochemical measurements show that the nanocapsule Pt/MWCNTs–Al₂O₃ catalyst has higher activity due to more uniform dispersion and smaller size of Pt nanoparticles, and higher stability ascribed to the stronger metal–support interaction (SMSI) between Pt nanoparticles and nanocapsule support than in Pt/MWCNTs. Furthermore, the carbon-riveted nanocapsule Pt/MWCNTs–Al₂O₃ catalyst has been designed and synthesized on the basis of in situ carbonization of glucose. The physical characteristics such as X-ray diffraction (XRD), energy dispersive analysis of X-ray (EDAX), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) have indicated that α-Al₂O₃ indeed entered into the inside of the MWCNTs and formed a nanocapsule support of MWCNTs with α-Al₂O₃ as stuffing. The accelerated potential cycling tests (APCT) show that carbon-riveted nanocapsule Pt/MWCNTs–Al₂O₃ possesses 10 times the stability of Pt/C and has 4.5 times the life-span of carbon-riveted Pt/TiO₂–C reported in our previous work. The significantly enhanced stability for carbon-riveted nanocapsule Pt/MWCNTs–Al₂O₃ catalyst is attributed to the reasons as follows: the inherently excellent mechanical resistance and stability of α-Al₂O₃ and MWCNTs in acidic and oxidative environments; SMSI between Pt nanoparticles and the nanocapsule support; the anchoring effect of the carbon layers formed during the carbon-riveting process (CRP); the increase of Pt(0) composition during CRP.