photodeposition-pd-onto-colloidal-au-nanorods-surface-plasmon

Photodeposition of Pd onto Colloidal Au Nanorods by Surface Plasmon Excitation

A protocol is described to photocatalytically guide Pd deposition onto Au nanorods (AuNR) using surface plasmon resonance (SPR). Excited plasmonic hot ...

U.S. Army Research Laboratory

Using electron beam lithography, amorphous Si (a-Si) nanopillars were fabricated with a height of 100 nm and diameters of 100, 200, 300, 500, and 1000 nm. The nanopillars were electrochemically cycled in a 1 M lithium trifluoromethanesulfonate in propylene carbonate electrolyte. In situ atomic force microscopy (AFM) was used to qualitatively and quantitatively examine the morphology evolution of the nanopillars including volume and height changes versus voltage in real-time. In the first cycle, an obvious hysteresis of volume change versus voltage during lithiation and delithiation was measured. The pillars did not crack in the first cycle, but a permanent volume expansion was observed. During subsequent cycles the a-Si roughened and deformed from the initial geometry, and eventually pillars with diameters >200 nm fractured. Furthermore, a degradation of mechanical properties is suggested as the 100 and 200 nm pillars were mechanically eroded by the small contact forces under the AFM probe. Ex situ scanning electron microscopy (SEM) images, combined with analysis of the damage caused by in situ AFM imaging, demonstrate that during cycling, the silicon became porous and structurally unstable compared to as-fabricated pillars. This research highlights that even nanoscale a-Si suffers irreversible mechanical damage during cycling in organic electrolytes. 

In situ atomic force microscopy of lithiation and delithiation of silicon nanostructures for lithium ion batteries.

Developing a solid state Photosystem I (PSI) modified electrode is attractive for photoelectrochemical applications because of the quantum yield of PSI, which approaches unity in the visible spectrum. Electrodes are constructed using a Nafion film to encapsulate PSI as well as the hole-scavenging redox mediator Os(bpy)2Cl2. The photoactive electrodes generate photocurrents of 4 μA/cm(2) when illuminated with 1.4 mW/cm(2) of 676 nm band-pass filtered light. Methyl viologen (MV(2+)) is present in the electrolyte to scavenge photoelectrons from PSI in the Nafion film and transport charges to the counter electrode. Because MV(2+) is positively charged in both reduced and oxidized states, it is able to diffuse through the cation permeable channels of Nafion. Photocurrent is produced when the working electrode is set to voltages negative of the Os(3+)/Os(2+) redox potential. Charge transfer through the Nafion film and photohole scavenging at the PSI luminal surface by Os(bpy)2Cl2 depends on the reduction of Os redox centers to Os(2+) via hole scavenging from PSI. The optimal film densities of Nafion (10 μg/cm(2) Nafion) and PSI (100 μg/cm(2) PSI) are determined to provide the highest photocurrents. These optimal film densities force films to be thin to allow the majority of PSI to have productive electrical contact with the backing electrode. 

Article	Year
In situ atomic force microscopy of lithiation and delithiation of silicon nanostructures for lithium ion batteries. ACS nano\| PubMed ID: 23992113	2013
Photoelectrochemistry of photosystem I bound in nafion. Langmuir : the ACS journal of surfaces and colloids\| PubMed ID: 25341002	2014

Cynthia A. Lundgren

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