Polyionic Nanoclays: Tailorable Hybrid Organic–Inorganic Catalytic Platforms

Abstract

We unveil the synthesis and initial application of a hybrid inorganic−organic architecture comprising two-dimensional, few nanometer-thick magnesium phyllo(organo)silicate nanosheets displaying an ordered array of covalently linked imidazolium functionalities. Accessible via a simple, one-pot ambient-temperature synthesis using a custom organosiloxane, these so-called polyionic nanoclays (PINCs) represent an emergent class of supported ionic liquid phase and hold a number of attractive features, including: (i) an extremely high ionic density (e.g., 3.8 mmol g −1 for the 1-methyl-3-propylimidazolium chloride PINC, roughly two-thirds the imidazolium cation density observed in the analogous free-flowing ionic liquid); (ii) the exchangeability of the associated counteranions to impart supplementary functionality or modulate solvent dispersibility; and (iii) the facility for tailoring the organic component, for example incorporating different (e.g., pyrrolidinium, pyridinium, phosphonium) or mixed onium moieties by employing the appropriate organosiloxane precursor(s). As a preliminary investigation of PINCs as nanocatalytic supports, we performed anion exchange with [AuCl 4 ] − , followed by in situ reduction to generate small (<5 nm) gold nanoparticles (AuNPs) on the clay lamellae. The resulting nanosized gold-modified PINCs dispersed in water exhibited an astonishing turnover frequency of 25 000 h −1 for 4-nitrophenol reduction at room temperature, making this hybrid material the most active gold nanocatalyst reported for this model reaction. Most remarkably, AuNPs supported on the PINC showed a dramatically enhanced catalytic activity (4000% increase) compared to similar gold nanoparticles suspended in water (600 h −1 ), suggesting a major synergistic effect arising from the PINC support. Overall, the generality and flexibility of this route to lamellar hybrid nanoclays, coupled with the ability to accommodate a wide range of pendant organic ionic moieties suggests an auspicious future for PINCs in catalysis, ion exchange, energy storage, separations, (bio)sensing, imaging, and the construction of nanoscale assemblies.

Substrate-Free Fabrication of Single-Crystal Two-Dimensional Gold Nanoplates for Catalytic Application

“…The intensity of the peak at 300 nm increased as the reaction time increased, whereas the absorption peak at 400 nm was the opposite. This catalytic reaction has been reported extensively and provided enriched kinetic data for comparison. − As illustrated in Figure S5 and Figure b–c, the catalyzed reaction may be completed in 5–22 min using varying amounts of gold nanoplates. Figure c indicated the reaction kinetics based on the relationship of ln­( A t / A 0 ) = ln­( C t / C 0 ) = k app · t , where k app was the apparent kinetic rate constant at room temperature and t was the reaction time.…”

Mesoporous Natural Fiber Welded Cellulose Containing Silver Nanoparticles as a Recyclable Heterogeneous Catalyst

“…4-NP Catalysis: NP catalysis was performed in accordance with procedures previously reported. [27,32] Briefly, a 20 mL aqueous solution com-prising 0.1 mm 4-NP and 50.0 mm NaBH 4 (bright yellow due to the presence of the 4-nitrophenolate ion) was stirred vigorously at room temperature (≈22 °C). Approximately 50 mg of catalyst composite were added to this solution to initiate the reduction of 4-NP to 4-AP.…”

Detection and detoxification of imidacloprid in food samples through ionic liquid-stabilized CuNi alloy nanoparticle-decorated multiwall carbon nanotubes

“…Environmental Science: Nano Paper Here, the proposed reason behind this enhancement may be due to π-π stacking between the IL and MWCNTs with IMD. 41 The degradation of IMD was performed in triplicate using CuNi/IL@MWCNTs. The linear correlation of ln C t vs. time was plotted (Fig.…”