Aero-ZnS architectures with dual hydrophilic–hydrophobic properties for microfluidic applications
Irina Plesco, Tudor Braniste, Niklas Wolff, Leonid Gorceac, Viola Düppel, Boris Cinic, Yogendra Kumar Mishra, Andrei Sarua, Rainer Adelung, Lorenz Kienle, I. M. Tiginyanu
Abstract
Here, we report on a new aero-material, called aero-ZnS, representing self-organized architectures made of ZnS hollow micro-tetrapod structures with nanoscale thin walls. The fabrication process is based on the hydride vapor phase epitaxy of CdS on sacrificial micro-tetrapods of ZnO with simultaneous or subsequent transformation of CdS into ZnS and removal of the sacrificial ZnO crystals. The nanostructure of the obtained ZnS hollow micro-tetrapods exhibits the polytypic intergrowth of wurtzite- and sphalerite-type phases perpendicular to their close packed planes. The inner surface of the micro-tetrapod walls preserves oxygen sites, as demonstrated by imaging based on electron energy-loss filtering. The self-organized aero-ZnS architecture proves to be hydrophilic under tension and hydrophobic when compressed against water. Self-propelled liquid marbles assembled using ZnS hollow micro-tetrapod structures are demonstrated.