Abstract
Long-chain ionic liquid, 1-hexadecyl-3-methylimidazolium chloride (C16mimCl), was firstly used as a linking agent to construct polystyrene (PS)/C16mimCl/palladium (Pd) beads. Subsequently, the PS/C16mimCl/Pd beads were used as a macroporous templating agent and C16mimCl was used as a mesoporous templating agent to prepare Pd-loaded hierarchical porous silica. A systematic study was carried out addressing the influence of the amount of C16mimCl and the mass ratios of m(Pd)/m(PS) on the PS/C16mimCl/Pd beads and the Pd-loaded hierarchical porous structures. The samples were characterized by electrophoresis experiments, SEM, TEM, small-angle XRD, and N2 adsorption–desorption experiments. It was found that the coverage of citrate-coated Pd nanoparticles (Pd NPs) onto the PS beads can be simply tailored by changing the amount of C16mimCl and the mass ratios of m(Pd)/m(PS). The resultant Pd-loaded hierarchical porous silica possessed a 3D ordered macroporous skeleton with a specific surface area of up to 967 m2 g−1, ordered mesoporous silica walls (SBA-3 type) and well-dispersed Pd NPs anchored on the inner walls of the spherical macroporous hollow. Importantly, the obtained Pd-loaded hierarchical porous silica exhibited an enhanced catalytic activity for the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) by H2O2.
Highlights
Long-chain ionic liquids (LILs), especially imidazolium-based LILs, have been most extensively studied for both fundamental research and practical applications.[1]
Our group has contributed much effort to successfully synthesize the mesoporous silica with high-quality cubic gyroid and 2D hexagonal mesoporous structures by using C16mimCl as template.[15]. These results indicated that the LILs have signi cantly stronger tendency toward self-aggregation and supramolecular templating in the preparation of ordered mesoporous structure
We found that C16mimCl is freely soluble in water at room temperature, which increases the possibility of the direct interaction between individual C16mimCl molecule and PS bead
Summary
Long-chain ionic liquids (LILs), especially imidazolium-based LILs, have been most extensively studied for both fundamental research and practical applications.[1] The LILs consist of a charged hydrophilic head group and a hydrophobic ‘tail’ domain, which can display the amphiphilic properties of conventional surfactants, and the speci city of the typical short-chain room temperature ionic liquids such as low melting point, strong polarity and high solubility in aqueous solution etc. Increasing efforts have been made to explore the selforganized behavior of the LILs in aqueous solution.[2] Various characterization methods, such as surface tension, electrical conductivity and uorescence measurement, have been used to determine the micelle formation and the micelle aggregation numbers of the LILs in aqueous solution.[3,4,5,6] The results indicated that the surface activity of the LILs is slightly superior to that of the typical cationic surfactants. These advantages of the LIL derivatives have been broadly applied in the
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