In this article, we report the synthesis of unique mesoporous Au-loaded Fe2O3nanoparticle assemblies (Au/Fe2O3-NPAs) through a surfactant-assisted aggregating assembly method. The resulting network structure, which composed of small Au nanocrystals (ca. 5 nm) finely dispersed on surface of Fe2O3 NPs (ca. 6–7 nm), possesses a 3D open-pore structure with a BET surface area of 123 m2g-1 and uniform mesopores (∼4.5 nm). Au/Fe2O3-NPAs showed high catalytic activity and chemical stability for the selective transformation of nitroaromatic compounds into the corresponding amines, using 1,1,3,3-tetramethyl disiloxane as reducing agent at ambient conditions.

The vertical TiO2 nanotube arrays constituting the core of 3-D nanoscale electrode architecture were synthesized over Ti sheet by anodization. Such formed TiO2 nanotubes are electrically conducting and amorphous as confirmed by XRD studies. Nanotube morphology is affected by water content and in the present study, close-packed 3-4 μm long TiO2 nanotube arrays of 45-50 nm diameter are formed with 2% water as revealed by the transmission and scanning electron microscopy. The redox active polypyrrole sheath is created by ultra-short pulsed current electropolymerization. Electrochemical properties of the 3-D nanoscaled TiO2 nanotube core-polypyrrole sheath electrodes relevant to the energy storage were investigated using cyclic voltammetry (CV) plots, electrochemical impedance spectroscopy (EIS), Charge discharge (CD) tests. High areal capacitance density of 48 mF cm-2 and low charge transfer resistance 12 Ω cm-2 with least ion diffusion limitation are realized at optimized polypyrrole sheath thickness. The Raman spectra studies reveal anion at specific chain locations involve in the redox process.

We developed a new soft-lithographic fabrication technique which enables the realization of high aspect-ratio PDMS micropillars. The key enabling factor is the adoption of the direct drawing technique incorporated with the in situ heating for simultaneous hardening and solidification of the PDMS micropillars. In addition, our technique allows self-aligned installation of highly reflective microspheres at the tips of the micropillars. Using the transparent PDMS micropillar as a flexible waveguide and the microsphere as a self-aligned reflector, we transformed the microsphere-tipped PDMS micropillars into all optically interrogated acoustic sensors inspired by the cricket’s filiform hairs and successfully demonstrated the sensing capability.