Towards Methanol Electrooxidation: Comparative Study on Imidazolium and Guanidinium Ionic Liquids Supported Pt Nanocrystals on Carbon Nanotubes

Towards Methanol Electrooxidation: Comparative Study on Imidazolium and Guanidinium Ionic Liquids Supported Pt Nanocrystals on Carbon Nanotubes

In this work, two types of ionic liquids (ILs), 1-hexadecyl-3-methylimidazolium chloride (C₁₆MIMCl) and 1,1,3,3-tetramethyl guanidinium bromide (TMGBr), were employed to assist the immobilization of Pt nanocrystals on carbon nanotubes (CNTs). It is found that the conjugated effects including the cations-π (C-N⁺•), π-π interactions and electrostatic interactions are the main drive forces between the quasi-aromatic imidazolium ring and pyrolytic graphite of CNTs in sample of C₁₆MIM-CNTs-Pt. The interactions of intra-molecular hydrogen bonds (N⁺-H•••N) and electrostatic interactions are found in the guanidinium ILs assisted catalysts (TMG-CNTs-Pt). The conjugated effects induce the formation of Pt(II) complexes in the composites even after the platinum precursor (H₂PtCl₆•6H₂O) was reduced by NaBH₄. The catalysis investigation towards methanol oxidation carried out in acidic solution demonstrates that both ternary composite (C₁₆MIM-CNTs- Pt and TMG-CNTs-Pt) catalysts exhibit higher electro-catalytic activity and better stability than the binary catalyst (CNTs-Pt) or the single-component catalyst (Pt nanocrystals).