Highly efficient CeO2 decorated nano-ZSM-5 catalyst for electrochemical oxidation of methanol

Abstract

Cerium oxide (CeO2) decorated nanocrystalline zeolite (Nano-ZSM-5) nanocomposites with different weight ratios were prepared by the calcination of a physical mixture of nanocrystalline CeO2 and Nano-ZSM-5. Materials were characterized by the complementary combination of X-ray diffraction, N2-adsorption, transmission electron microscopic, and X-ray photoelectron spectroscopic techniques. The material was investigated as a precious-metal-free electrode catalyst for methanol oxidation. The electrochemical oxidation of methanol was investigated at a CeO2/Nano-ZSM-5 modified glassy-carbon electrode in alkaline medium using electrochemical impedance spectroscopy, cyclic voltammetry, and chronoamperometry. Comparative investigations were made with commercial Pt(20%)/C catalyst with respect to current density, stability, and CO tolerance capacity. CeO2/Nano-ZSM-5 with a weight ratio of 30% exhibited remarkably high electrocatalytic activity in the methanol oxidation in comparison to nanocrystalline CeO2 and commercial Pt (20%)/C catalyst. The material was found to exhibit stable electrocatalytic activity even after 1000 cycles. High electrocatalytic activity in the methanol oxidation can be attributed to the synergistic contribution provided by CeO2 nanocrystals and Brønsted acidity of the high-surface-area Nano-ZSM-5. Results demonstrate that the excellent current density and high stability of CeO2/Nano-ZSM-5 would be valuable for its commercial application in direct methanol fuel cells.