Halloysite-Based Nanomotors with Embedded Palladium Nanoparticles for Selective Benzyl Alcohol Oxidation

The liquid-phase oxidation benzyl alcohol using hydrogen peroxide (H2O2) as an oxidant is a promising and green strategy for manufacturing aldehydes or/and ketones. Herein palladium (Pd) nanoparticles were impregnated in lumens of halloysite nanotubes by using ionic liquid (1-(2'-hydroxylethyl)2,3-dimethylimidazolium chloride) as directing agents. On the basis of the asymmetric scroll-like structure of halloysite and the catalytic decomposition ability of Pd toward H2O2, the prepared catalyst (Pd-IL-HNTs) exhibited powerful self-propelled movement at an average speed of 276 +/- 35 mu m/s in 30.0 wt % H2O2 solution. The specific interaction between nanomotors and benzyl alcohol was observed as a consequence of self-moving behavior and hydrophobic interaction introduced by ionic liquid. With the synergistic coupling of the catalytic ability and powerful movement, Pd-IL-HNTs displayed outstanding catalytic benzyl alcohol oxidation performance. Compared to other nonpropelling catalysts using lamellar clay (montmorillonite and kaolinite) as supports, such HNT-based nanomotors registered superior catalytic performance, and the TOF value of 118.1 h(-1) was obtained.