Yongmei Bai

Solvothermal synthesis of hierarchical Co3O4 flower-like microspheres for superior ethanol gas sensing properties

In this paper, hierarchical Co3O4 flower-like microspheres have been successfully synthesized on the basis of morphology-conserved transformation method. The key step of this method is to construct flower-like microstructures of the cobalt-containing precursors via manipulating the synthetic parameters in a facile ethylene glycol mediated solvothermal reaction. The as-prepared flower-like microspheres are formed from the assembly of many two-dimensional nanosheets, accompanied by an outside-in dissolution and recrystallization process. Finally, hierarchical Co3O4 microspheres with conserved flower-like morphology are obtained through the moderate calcination. When evaluated as a gas sensor, the obtained Co3O4 flower-like microspheres exhibit a good response and sensitivity towards ethanol gas, suggesting their promising potential for gas sensors application.

Adhesion and friction studies on silicon dioxide nanoparticle-textured surfaces prepared by the spin-coating process

Silicon dioxide nanoparticle-textured surfaces were prepared by the spin-coating process. The adhesion and friction properties of the nanoparticle-textured surfaces were investigated using an atomic force microscope colloidal probe. Experimental results revealed that the nanoparticle-textured surfaces can significantly reduce adhesive and friction forces compared with a flat surface. The main reason for this phenomenon was that the nanotexture can reduce contact area between the sample surface and the colloidal probe. The relationships between surface root mean square (RMS) roughness, packing density, and spinning rate were also discussed. The effects of surface RMS roughness and packing density on the adhesion and friction behaviors of the nanotextured surfaces were investigated. The adhesive and friction forces of the nanoparticle-textured surfaces decreased with increasing packing density. The friction forces of the nanoparticle-textured surfaces increased with increasing applied load and sliding velocity. This approach should be applied to new developments in nanosystems to reduce adhesive and friction forces between contact pairs.