Pd nanoparticles deposited on poly(lactic acid) grafted carbon nanotubes: Synthesis, characterization and application in Heck C–C coupling reaction

Herein we described the synthesis of a novel f-CNTs-Pd nanocatalyst by covalent grafting of poly(lactic acid) (PLA) onto carbon nanotubes (CNTs) and subsequent deposition of Pd nanoparticles. Prior to grafting of PLA, CNTs were oxidized with a mixture of HNO3/H2SO4 and successively activated with thionyl chloride. The PLA grafted CNTs (f-CNTs) were then used as platform for in situ deposition of Pd nanoparticles. The formation of f-CNTs-Pd nanocatalyst was analyzed by UV–vis, FTIR and Raman spectroscopy, powder XRD, energy dispersive spectroscopy and thermogravimetric analysis. The morphologies of the nanocatalyst were characterized using scanning and transmission electron microscopes. The f-CNTs stabilized Pd nanoparticles are found to be more effective in the promotion of Heck cross-coupling reaction between aryl halides and n-butyl acrylate. The f-CNTs-Pd nanocatalyst was regenerated for three cycles of reaction without any significant loss in its activity.

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► High catalytic activity of f-CNTs-Pd was demonstrated through Heck reaction.
► CNTs were effectively functionalized by covalent grafting of poly(lactic acid).
► Functionalized CNTs were utilized as platform for deposition of Pd nanoparticles.
► Covalently grafted poly(lactic acid) on CNTs was observed by TEM.
► f-CNTs-Pd is easily recoverable and maintains its activity over a number of cycles.