Designed as a high-capacity alloy host for Na-ion chemistry, a forest of Sn nanorods with a unique core-shell structure was synthesized on viral scaffolds, which were genetically engineered to ensure a nearly vertical alignment upon self-assembly onto a metal substrate. The interdigital spaces thus formed between individual rods effectively accommodated the volume expansion and contraction of the alloy upon sodiation/desodiation, while additional carbon-coating engineered over these nanorods further suppressed Sn aggregation during extended electrochemical cycling. Due to the unique nanohierarchy of multiple functional layers, the resultant 3D nanoforest of C/Sn/Ni/TMV1cys, binder-free composite electrode already and evenly assembled on a stainless steel current collector, exhibited supreme capacity utilization and cycling stability toward Na-ion storage and release. An initial capacity of 722 mA·h (g Sn)(-1) along with 405 mA·h (g Sn)(-1) retained after 150 deep cycles demonstrates the longest-cycling nano-Sn anode material for Na-ion batteries reported in the literature to date and marks a significant performance improvement for neat Sn material as alloy host for Na-ion chemistry.

No abstract

No abstract

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.

Photocatalytic assembly of heterometallic nanoarchitectures via plasmonic hot electrons is demonstrated by liquid-phase, reductive photodeposition of platinum (Pt) onto gold nanorods (AuNR) under longitudinal surface plasmon (LSP) excitation. Nucleation of Pt 0 from PtCl 6 2−was initiated by plasmonic hot electrons at the Au surface. Sub-5 nm epitaxial overgrowth of Pt followed a core−shell morphology. Measured 6.5 longitudinal:transversal growth aspect ratio revealed longitudinal growth preferentiality that was consistent with the LSP dipole polarity. In situ spectroscopic monitoring of the photocatalytic growth process permitted real-time feedback into Au surface functionalization with PtCl 6 2− according to 16 nm red-shift in its Cl−Pt ligand-to-metal charge-transfer (L π MCT) band involving ligand π orbitals. Subsequent Pt 0 growth kinetics were tracked using the L π MCT band. Discrete dipole models elucidated evolving lightmatter interactions of Pt-decorated AuNR that were consistent with experimental characterization. These studies provide a foundational mechanistic understanding toward guided assembly of heterometallic nanoarchitectures at ambient conditions via plasmonic hot electrons.