We synthesized Co(OH)2/graphene composites from graphite without a graphene oxide (GO) step. The Co(OH)2/graphene composite exhibited a specific capacitance of 960 F g−1 at a current density of 10 A g−1.
Slanted high‐aspect‐ratio polymer pillars are studied for their unique properties such as unidirectional spreading of liquid, directional adhesions, or alignment of cells, where the pillars are in constant contact with water or in a humid environment. These pillars, however, tend to cluster upon water evaporation due to the capillary force and lowered modulus of the pillars. Here, spontaneous recovery of clustered slanted hydrogel pillars to their original shape is presented by exploiting the modulus change of hydrogel materials during water evaporation. The clustering and recovery of the slanted hydrogel micropillars are monitored in situ by optical microscopy and environmental scanning electron microscopy. To elucidate sequential clustering and recovery mechanism, the adhesion force between the pillars and the restoring force is compared. Finally, the dynamic change of optical transparency is exploited as the result of switching between clustering and recovery of the slanted micropillars for display. The study of the deformation and recovery of slanted hydrogel pillars will offer insights into geometrical and material designs in water‐based applications.
We report on the first synthesis of porous ZrO2-SiO2 sheets with well-defined ultrasmall WO3 nanoparticles for energy storage performance. In our system, for improving the surface deterioration of electrode, we use the ZrO2-SiO2 sheets using graphene oxide as a template to access electrode substrate. The synthesized electrode with about 20 nm thickness and about 10 nm pores, has a maximum value of 313 F/g at current density of 1 A/g and a minimum value of 160 F/g at current density of 30 A/g in the specific capacitance. In addition, over 90% of its initial specific capacitance is retained when they are cycled up to 2500 cycles.
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