Spontaneous formation of micrometer-size inorganic peapods.

We show that polyoxometalate (ammonium phosphomolybdate) Keggin in aqueous dispersions upon sonication spontaneously transforms into micrometer-sized, peapod-shaped structures. The formation of these peapods is preceded by the generation of spherical aggregates. The particles have been characterized experimentally by time-resolved dynamic light scattering (DLS), transmission electron microscopy (TEM), and scanning TEM with a high-angle annular dark field detector (STEM-HAADF) for energy-dispersive X-ray (STEM/EDX) elemental analyses.

Synthesis and characterization of large surface hexagonal polyoxometalate platelets.

The polyoxometalates, or POMs (clusters comprising at least two metal and many oxygen atoms), have recently gained significant interest, owing to their versatile architecture and especially catalytic activities. Due to their high catalytic activity but low surface area, there is always a demand for making high-surface-area POMs, particularly high-surface-area Keggins. Our present work demonstrates the 'gluing' of the anionic phosphomolybdate Keggin on gibbsite nanoplatelets with a residual positive charge to form large-surface-area composites.