Surfactant-Directed Assembly Synthesis Of Pd Nanoparticls As Nanoreactor For Effective Decholorination Of 4-CP In Water

Surfactant is recognized as an excellent supporter for the ultrafine metal nanoparticles(NPs)formation due to its rich functional groups and self-assembly property.Here we report a facile one-pot synthesis method for the production of wellordered PdNPs assemblies with high catalysis activity and stability for the effective dechlorination of 4-chlorophenol(4-CP).The formed PdNPs assemblies with specified geometric structures are directed by the surfactant assembly,depending on the concentration of cetyltrimethylammonium bromide(CTAB).For example,loosethey could further evolve into nanocube assemblies upon raising the surfactant concentration.The electrostatic interaction between cationic surfactants and anionic Pd precursors that can effectively shield the repulsion of positively-charged head groups(CTA+)provides a driving force for the surfactant assembly at a molecular level,and the surfactant concentration is critical for the ordered geometric morphology of PdNPs assemblies formation at a mesoscale level.More importantly,the rapid catalytic activity and high dehalogenation capacity of the PdNPs assemblies is demonstrated by using the 4-CP dechlorination as a probe reaction,the decholorination rate is 100% within 45 min.Due to the amphipathic and selfassembled property of surfactant,a PdNPs-decorated nanoreactor with a substrates-rich(4-CP and atomic hydrogen species)microenvironment and concentrated of Pd nanocatalystsembedded inside is created,greatly beneficial for facilitating the catalytic dechlorination performance of PdNPs.Overall,there is a synergistic effect betweenPdNPs and surfactant molecules on the catalytic activity and stability of the PdNPs assemblies.Moreover,the recycle tests indicate that the PdNPs assemblies have excellent catalytic ability and recyclability,where ca.87% of dechlorination efficiency within 60 min can still be achieved after 8 times repeated treatment.In this regard,this study not only reports a facile method to prepare well-ordered PdNPs assemblies,but also provides an alternative insight on effective water remediation via nanoreactor by simultaneously taking advantages of both the surfactant washing and the heterogeneous catalysis approaches.