▎ 摘　　要

The magnetite nanoparticles on graphene oxide (Fe3O4@GO) nanofiller are synthesized, and incorporated in a polymeric matrix to produce effective electrolyte membrane for direct alkaline methanol/ethanol fuel cells. Fe3O4@GO nanofillers (0.1%) are gradiently distributed along the through-plane direction in a quaternized poly (vinyl alcohol) (QPVA) membrane by applying an external magnetic field (MF) during the film drying step. The present study is the first work to illustrate a facile method to form gradient distribution of nanofillers in a QPVA matrix via applying MF, resulting in a polymer-rich region in the center and a nanofiller-rich region near the membrane surface. This MF assisted QPVA/0.1% Fe3O4@GO nanocomposite membrane exhibits decreased dimensional changes without sacrificing the potassium hydroxide (KOH) doping level compared to QPVA. This nanocomposite membrane design not only reduces the permeability but also improves the ionic conductivity. Maximum power densities of 200 and 144.3 mW cm(-2) are achieved when the fuel cell is fed with 2 M methanol or 3 M ethanol at 60 degrees C using the magnetic-field assisted nanocomposite electrolyte. The fabrication of high-performance nanocomposite membrane electrolytes using a MF implies promising potential and an innovative future trend for fuel cells.