A Surfactant-Encapsulating Polyoxometalate Nanowire Assembly as a New Carrier for Nanoscale Noble-Metal Catalysts

The loading of noble-metal nanoparticles (NMNPs) onto various carriers to obtain stable and highly efficient catalysts is currently an important strategy in the development of noble metal (NM)-based catalytic reactions and their applications. We herein report a nanowire supramolecular assembly constructed from the surfactant-encapsulating polyoxometalates (SEPs) CTAB-PW12, which can act as new carriers for NMNPs. In this case, the Ag NPs are loaded onto the SEP nanowire assembly with a narrow size distribution from 5 to 20nm in diameter; the average size is approximately 10nm. The Ag NPs on the nanowire assemblies are well stabilized and the over agglomeration of Ag NPs is avoided owing to the existence of well-arranged polyoxometalate (POM) units in the SEP assembly and the hydrophobic surfactant on the surface of the nanowire assembly. Furthermore, the loading amount of the Ag NPs can be adjusted by controlling the concentration of the AgNO3 aqueous solution. The resultant Ag/CTAB-PW12 composite materials exhibit high activity and good stability for the catalytic reduction of 4-nitrophenol (4-NP) with NaBH4 in isopropanol/H2O solution. The NMNPs-loaded SEP nanoassembly may represent a new composite catalyst system for application in NM-based catalysis.