Improving the direct methanol fuel cell performance with poly(vinyl alcohol)/titanium dioxide nanocomposites as a novel electrolyte additive

• Surface modification of TiO2 was performed with KH550 as a coupling agent.
• PVA/TiO2 nanocomposites were prepared by using ultrasound irradiation.
• All data indicate that the nanoparticles were dispersed in PAI matrix on nanoscale.
• Using PVA/TiO2 nanocomposites as a novel electrolyte additive in DMFC.
• The catalyst gain higher activity for methanol oxidation reaction.

The present investigation deals with the fabrication of new poly(vinyl alcohol)/titanium dioxide (PVA/TiO2) nanocomposites (NCs) with different titanium dioxide (TiO2) loading by using ultrasound irradiation. For the improvement of nanoparticles (NPs) dispersion and increasing possible interactions between NPs and PVA, the surface of TiO2 NPs was modified by γ-aminopropyltriethoxy silane. The as-prepared NCs were characterized by spectroscopic, thermogravimetric analysis and electron microscopy methods. The results demonstrate that NPs dispersed homogeneously within the PVA matrix on nanoscale, which could be assigned to the hydrogen and covalent bonds formed between PVA and NPs. The results indicated that heat stability of NCs was improved in the presence of modified TiO2 NPs. The mechanisms of surface modification and a possible mechanism of ultrasonic induced interaction between polymer and NPs have been analyzed.Then, these NCs have been used as a novel electrolyte additive in alkaline half cell to improve the electrical efficiency of the direct methanol fuel cell (DMFC). Finally, the electrochemical characteristics of the half cell of DMFC which employ the PVA/TiO2 NCs were investigated. The results reveal that introduction of NCs within electrolyte can modify the electronic property of Pt surface and improve the electrocatalytic activity of Pt in methanol oxidation and prevents catalyst from more poisoning by intermediate products of methanol oxidation.

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