Chlorinated polyvinylchloride (CPVC) nanofiber mats were prepared by an electrospinning technique, and then treated with amines of different chemical structures, followed by immobilization of palladium catalysts (CPVC–NH2–Pd), which have been demonstrated as efficient, stable and easily recyclable heterogeneous catalysts. Their catalytic activities could be correlated with the binding energies of the palladium species with the amine chelating ligands.

An efficient and recyclable ligand-free heterogeneous catalyst has been prepared by the immobilization of palladium onto ground pearl shell powders (Pd/shell powders, Pd/SP). The catalytic activity and recyclability of the prepared Pd/SP along with the charcoal and calcium carbonate supported palladium (Pd/C and Pd/CaCO3) catalysts have been evaluated using the reductive homocoupling of aromatic halides. Pd/SP not only has higher catalytic activity, but also exhibits much stronger stability than Pd/C and Pd/CaCO3. The remarkable Pd/SP stability has been attributed to the chelation of palladium species with the surface chitin and protein molecules of the supported pearl shell powders. The X-ray photoelectron spectroscopy (XPS) studies show that the reductive Pd0 species can be regenerated in situ from the oxidative Pd2+ species for the Pd/SP catalyzed reductive homocoupling of aromatic halides in ethanol/DMSO solution, suggesting that the heterogeneous and homogeneous palladium catalysis proceeds through a similar Pd0/Pd2+ cycle catalytic mechanism.