Quaternized polyhedral oligomeric silsesquioxanes stabilized Pd nanoparticles as efficient nanocatalysts for reduction reaction

Hydrophilic quaternized polyhedral oligomeric silsesquioxane (QPOSS) stabilized palladium nanoparticles hybrids (PdNPs@QPOSS) were successfully constructed for catalytic reduction of organic dyes and nitrophenols. The size of PdNPs can be effectively regulated through the molar ratio between QPOSS and Pd precursors. Uniformly dispersed nano-sized QPOSS encapsulated ultra-fine PdNPs with average diameter of 2.38 nm were obtained as the molar ratio of precursors was 1:8. It was found that low-dose PdNPs@QPOSS nanohybrids as catalysts exhibited outstanding catalytic reduction activity for methylene blue (MB) and nitrophenol (4-NP) with high conversion frequencies (TOF) of 213.7 and 17.8 min(-1) respectively, which is superior to commercial Pd/C catalyst. The nanocatalysts we prepared could be stably dispersed in water for one month and there was no significant loss of catalytic activity in four catalytic cycle. The enhanced catalytic activity and good stability can be attributed to QPOSS as a stabilizer having strong coordination with as-generated PdNPs. In addition, we evaluated the decolorizing properties of common organic pollutants including methyl orange (MO), congo red (CR), methyl orange (MO), rhodamine 6G (R6G), rhodamine B (RhB), rhodamine 6G (R6G), and nitrophenol derivatives. The organic-inorganic hybrid nanocatalyst PdNPs@QPOSS is very effective in catalytic reduction of a series of colored dyes and nitrophenols, which also means that the nanohybrid as catalyst has a wide range of applications in industrial degradation of organic pollutants in wastewater.