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

Abstract

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 raspberry-like 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.