Alkali doped polyvinyl alcohol/multi-walled carbon nano-tube electrolyte for direct methanol alkaline fuel cell

A novel route to functionalize polyvinyl alcohol (PVA) onto multi-walled carbon nano-tube (MWCNT) is reported in this work. FTIR, XPS, Raman spectroscopy, and TGA data confirmed PVA grafting onto the MWCNT. The grafted PVA content was estimated to be 25% in the PVA–functionalized MWCNT. A nano-composite consisting of PVA and 0.05% functionalized CNT was successfully prepared using a solution casting method. Water solubility and diffusivity were enhanced in the CNT-containing membranes. The ionic conductivity of the potassium hydroxide (KOH)-doped PVA/CNT membrane was improved by adding the functionalized CNT, which might be ascribed to the ionic channels provided by the CNT. The methanol permeability was suppressed in the CNT-containing sample. The alkali-doped electrolytes were applied in direct methanol alkaline fuel cells. An open-circuit potential and a peak power density of 0.86 V and 39 mW cm−2 were obtained using a 2 M methanol fuel in 6 M KOH at 60 °C with the PVA/CNT/KOH electrolyte, significantly higher than those without CNT incorporation.