Achieving Fast Oxygen Reduction on Oxide Electrodes by Creating 3D Multiscale Micro-Nano Structures for Low-Temperature Solid Oxide Fuel Cells.

Fast oxygen reduction reaction (ORR) at the cathode is a key requirement for the realization of low-temperature solid oxide fuel cells (SOFCs). While the design of three-dimensional (3D) structures has emerged as a new and promising approach to improving the electrochemical performance of SOFC cathodes, achieving versatile structures and structural stability is still challenging. In this study, we demonstrate a novel architectural design for a superior cathode with fast ORR activity.

Quasi-seamless stitching for large-area micropatterned surfaces enabled by Fourier spectral analysis of moiré patterns.

The main challenge in preparing a flexible mold stamp using roll-to-roll nanoimprint lithography is to simultaneously increase the imprintable area with a minimized perceptible seam. However, the current methods for stitching multiple small molds to fabricate large-area molds and functional surfaces typically rely on the alignment mark, which inevitably produces a clear alignment mark and stitched seam. In this study, we propose a mark-less alignment by the pattern itself method inspired by moiré technique, which uses the Fourier spectral analysis of moiré patterns formed by superposed identical patterns for alignment.

Microstructured Surfaces for Reducing Chances of Fomite Transmission via Virus-Containing Respiratory Droplets.

Evaporation-induced particle aggregation in drying droplets is of significant importance in the prevention of pathogen transfer due to the possibility of indirect fomite transmission of the infectious virus particles. In this study, particle aggregation was directionally controlled using contact line dynamics (pinned or slipping) and geometrical gradients on microstructured surfaces by the systematic investigation of the evaporation process on sessile droplets and sprayed microdroplets laden with virus-simulant nanoparticles. Using this mechanism, we designed robust particle capture surfaces by significantly inhibiting the contact transfer of particles from fomite surfaces.

Octave-spanning mid-infrared femtosecond OPA in a ZnGeP pumped by a 2.4 μm Cr:ZnSe chirped-pulse amplifier.

We report on the highly efficient, octave-spanning mid-infrared (mid-IR) optical parametric amplification (OPA) in a ZnGeP (ZGP) crystal, pumped by a 1 kHz, 2.4 μm, 250 fs Cr:ZnSe chirped-pulse amplifier. The full spectral coverage of 3-10 μm with the amplified signal and idler beams is demonstrated.

Ultrafast fluorescent decay induced by metal-mediated dipole-dipole interaction in two-dimensional molecular aggregates.

Two-dimensional molecular aggregate (2DMA), a thin sheet of strongly interacting dipole molecules self-assembled at close distance on an ordered lattice, is a fascinating fluorescent material. It is distinctively different from the conventional (single or colloidal) dye molecules and quantum dots. In this paper, we verify that when a 2DMA is placed at a nanometric distance from a metallic substrate, the strong and coherent interaction between the dipoles inside the 2DMA dominates its fluorescent decay at a picosecond timescale.

Probing the lithium ion storage properties of positively and negatively carved silicon.

Here, we report Si pillar and well arrays as tailored electrode materials for advanced Li ion storage devices. The well-ordered and periodic morphologies were formed on a Si electrode thin film via laser interference lithography followed by a dry etch process. Two different patterns of negatively or positively carved Si electrodes exhibited highly improved cycle performance as a consequence of the enlarged surface area and the nanoscale pattern effects.

Copper nanofiber-networked cobalt oxide composites for high performance Li-ion batteries.

We prepared a composite electrode structure consisting of copper nanofiber-networked cobalt oxide (CuNFs@CoOx). The copper nanofibers (CuNFs) were fabricated on a substrate with formation of a network structure, which may have potential for improving electron percolation and retarding film deformation during the discharging/charging process over the electroactive cobalt oxide. Compared to bare CoOxthin-film (CoOxTF) electrodes, the CuNFs@CoOxelectrodes exhibited a significant enhancement of rate performance by at least six-fold at an input current density of 3C-rate.

SnO(2) nanorod-planted graphite: an effective nanostructure configuration for reversible lithium ion storage.

We report a novel architecture of SnO(2) nanorod-planted graphite particles for an efficient Li ion storage material that can be prepared by a simple catalyst-assisted hydrothermal process. Rectangular-shaped SnO(2) nanorods are highly crystalline with a tetragonal rutile phase and distributed uniformly over the surface of micrometer-sized graphite particles. In addition, the size dimensions of grown SnO(2) nanorods can be controlled by varying the synthesis conditions.

Size controlled nickel oxide nanoparticles on carbon nanotubes for supercapacitor electrode.

We have synthesized supercapacitor electrodes fashioned of NiO(x)/multiwalled carbon nanotubes (MWNTs), in which the controlled NiO(x) nanoparticles were prepared via a simple colloidal method and supported on the MWNTs. The sizes of the NiO(x) nanoparticles on MWNTs were systematically varied from 4 to 14 nm at a fixed metal loading of 20 wt% by changing sintering temperature in a controlled manner. The maximum specific capacitance of the NiO(x)/MWNTs was measured to be ca.

Patterned array of nanoparticles on substrates via contact printing method with CNTs/AAO stamp.

Patterned arrays of Fe oxide nanoparticles were transferred via contact printing method on a substrate surface using carbon nanotubes embedded in anodic aluminum oxide (CNTs/AAO) as a stamp, in which vertically aligned CNTs in hexagonally patterned array was first fabricated by chemical vapor deposition into the AAO, followed by a partial chemical etching to expose the CNTs from the AAO. Fe precursor inked CNTs stamp was contact-printed on a Pt-coated Si substrate, and after heat treatment at 200 degrees C, patterned array of Fe oxide nanoparticles with ca. 80 nm of diameter and ca.