Highly active catalysts: Double-shelled hollow nanospheres with tiny Pt NPs

A facile strategy was reported to fabricate a novel Pt-based metal oxide double-shelled hollow nanospheres (MDSHs), which avoided the traditional tedious procedures. It was attractive that the formation mechanism of DSHs involved redeposition of etch-released silica species and self-assembly of metal oxide units. To verify the successful synthesis and structure features of Pt-LCDSHs catalyst, the as-prepared samples were characterized by several techniques, such as SEM, N 2 adsorption–desorption isotherm analysis, TEM, EDX, XRD and XPS. Results indicated that all of MDSHs possessed double-shelled structures with both the inner and outer shells composing of metal oxide units. Interestingly, the metal oxide of the DHSs could offer abundant active points for Pt NPs and the space between the double shells also could be filled with Pt NPs. What's more, compared with the pure samples, the Pt-embedded La 2 O 3 -CeO 2 -DSHs exhibited the highest catalytic performance (6.58 × 10 −3 min −1 ) and good reusability with a conversion of 94% even after eight cycles, which were evaluated by means of the reduction of 4-nitrophenol monitored by UV–vis spectra. Finally, a possible reaction mechanism for the reduction reaction on Pt-based La 2 O 3 -CeO 2 -DSHs was also proposed.