Lithiation of Rutile TiO₂‑Coated Si NWs Observed by in Situ TEM

Lithiation of Rutile TiO₂‑Coated Si NWs Observed by in Situ TE

Lithiation of Rutile TiO₂‑Coated Si NWs Observed by in Situ TEM

Lithiation of Rutile TiO₂‑Coated Si NWs Observed by in Situ TE

ZnO/CuO Heterojunction Branched Nanowires for Photoelectrochemical Hydrogen Generation

We report a facile and large-scale fabrication of three-dimensional (3D) ZnO/CuO heterojunction branched nanowires (b-NWs) and their application as photocathodes for photoelectrochemical (PEC) solar hydrogen production in a neutral medium. Using simple, cost-effective thermal oxidation and hydrothermal growth methods, ZnO/CuO b-NWs are grown on copper film or mesh substrates with various ZnO and CuO NWs sizes and densities. The ZnO/CuO b-NWs are characterized in detail using high-resolution scanning and transmission electron microscopies exhibiting single-crystalline defect-free b-NWs with smooth and clean surfaces. The correlation between electrode currents and different NWs sizes and densities are studied in which b-NWs with longer and denser CuO NW cores show higher photocathodic current due to enhanced reaction surface area. The ZnO/CuO b-NW photoelectrodes exhibit broadband photoresponse from UV to near IR region, and higher photocathodic current than the ZnO-coated CuO (core/shell) NWs due to improved surface area and enhanced gas evolution. Significant improvement in the photocathodic current is observed when ZnO/CuO b-NWs are grown on copper mesh compared to copper film. The achieved results offer very useful guidelines in designing b-NWs mesh photoelectrodes for high-efficiency, low-cost, and flexible PEC cells using cheap, earth-abundant materials for clean solar hydrogen generation at large scales

Tunable, Endotaxial Inclusion of Crystalline Pt-Based Nanoparticles Inside a High-Quality Bronze TiO₂ Matrix

A series of high-quality bronze titanium oxide films containing endotaxially embedded Pt-based nanoparticles was fabricated using pulsed laser deposition under various oxygen partial pressures (0 to 50 mTorr). We found that morphological control over the embedded Pt nanoparticles is possible by varying the oxygen partial pressure during growth. We also found that the titanium oxide matrix plays an important role in controlling composition, shape, and distribution of the endotaxially embedded Pt-based nanoparticles over this range of oxygen partial pressure by affecting (1) the formation of a segregated layer of Pt–Ti alloy nanoparticles, in addition to the pure Pt nanoparticles, under vacuum, (2) the generation of crystallographic twinning, steps, and kinks within the Pt nanoparticles, and (3) the localized precipitation of Pt nanoparticles spatially confined and morphologically adapted to the extended defects within the matrix

Accordion Strain Accommodation Mechanism within the Epitaxially Constrained Electrode

The tremendous benefits of all-solid-state Li-ion batteries will only be reaped if the cycle-induced strain mismatch across the electrode/electrolyte interfaces can be managed at the atomic scale to ensure that structural coherency is maintained over the lifetime of the battery. We have discovered a unique strain accommodation mechanism within an epitaxially constrained high-performance bronze TiO₂ (TiO₂-B) electrode that relieves coherency stresses that arise upon Li insertion. In situ transmission electron microscopy observation reveals the formation of anatase shear bands within the TiO₂-B crystal that play the same role that interface dislocations do to relieve growth stresses. While first-principles calculations indicate that anatase is the favored crystal structure of TiO₂ in the lithiated state, its continued propagation is suppressed by the epitaxial constraints of the substrate. This discovery reveals an accordion-like mechanism relying on an otherwise undesirable structural transformation that can be exploited to manage the cyclic strain mismatch across the electrode/electrolyte interfaces that plague all solid-state batteries

Direct Realization of Complete Conversion and Agglomeration Dynamics of SnO₂ Nanoparticles in Liquid Electrolyte

The conversion reaction is important in lithium-ion batteries because it governs the overall battery performance, such as initial Coulombic efficiency, capacity retention, and rate capability. Here, we have demonstrated in situ observation of the complete conversion reaction and agglomeration of nanoparticles (NPs) upon lithiation by using graphene liquid cell transmission electron microscopy. The observation reveals that the Sn NPs are nucleated from the surface of SnO₂, followed by merging with each other. We demonstrate that the agglomeration has a stepwise process, including rotation of a NP, formation of necks, and subsequent merging of individual NPs

High-Energy and Long-Lasting Organic Electrode for a Rechargeable Aqueous Battery

Redox-active organic materials (ROMs) hold great promise as potential electrode materials for eco-friendly, cost-effective, and sustainable batteries; however, the poor cycle stability arising from the chronic dissolution issue of the ROMs in generic battery systems has impeded their practical employment. Herein, we present that a rational selection of electrolytes considering the solubility tendency can unlock the hidden full redox capability of the DMPZ electrode (i.e., 5,10-dihydro-5,10-dimethylphenazine) with unprecedentedly high reversibility. It is demonstrated that a multiredox activity of DMPZ/DMPZ+/DMPZ2+, which has been previously regarded to degrade with repeated cycles, in the newly designed electrolyte can be utilized with surprisingly robust cycle stability over 1000 cycles at 1C. This work signifies that tailoring the electrode–electrolyte compatibility can possibly unleash the hidden potential of many common ROMs, catalyzing the rediscovery of organic electrodes with long-lasting and high energy density

Quantitative real-time PCR results of <i>CDK4</i> amplification by a) well-differentiated (WD) and dedifferentiated (DD) liposarcomas: amplification levels were not different between the two histologic subtypes.

<p>Quantitative real-time PCR results of <i>CDK4</i> amplification in <b>b)</b> WD and <b>c)</b> DD liposarcomas according to tumor recurrence: amplification was higher in WD liposarcomas with recurrence after surgical resection, but not different in DD liposarcomas regardless of tumor recurrence.</p

Predictors of Recurrence-free Survival for Well-differentiated Liposarcoma in Univariate and Multivariate Analyses.

<p>HR, hazard ratio; CI, confidence interval.</p

CDK4 Immunohistochemistry Results According to Tumor Recurrence.

<p>WD, well-differentiated; DD, dedifferentiated; IHC immunohistochemistry.</p