Synergetic effect of polydopamine particles and in-situ fabricated gold nanoparticles on charge-dependent catalytic behaviors

The versatile catechol unit of polydopamine (PDA) endows this molecule with a broad ranging adhesive properties and reducibility.We prepared free-standing PDA particles by a simple self-polymerization and these particles served as both an effective reductant and scaffold for a hybrid catalyst.The raspberrylike nanocomposites featured a high density of AuNPs uniformly deposited on PDA particles (PDA@Au).This system was prepared in-situ with assistance from the active catechol and amine groups of the PDA particles.To quantify the effect of the PDA carriers,we studied the catalytic activity of the PDA and PDA@Au particles.The PDA particles showed a pronounced charge-dependent catalytic activity for reduction of cationic methylene blue,negatively-charged 4-nitrophenolate,and zwitterionic rhodamine B in the presence of borohydride,whereas PDA@AuNPs showed catalytic activity with a less pronounced charge-dependence of the catalytic efficiency of the AuNPs.The PDA particles served as a redox mediator and adsorbent accelerator in degradation of the dyes owing to its unique chemical structure.