Flash Ignition of Freestanding Porous Silicon Films: Effects of Film Thickness and Porosity

We report the first successful xenon flash ignition of freestanding porous Si films in air. The minimum flash ignition energy (<i>E</i>_min) first decreases and then increases with increasing the porous Si film thickness due to the competition between light absorption and heat loss. The <i>E</i>_min is lower for higher porosity film because high porosity reduces both the heat capacity and the thermal conductivity, facilitating the temperature rise. These results are important for initiating controlled porous Si combustion and preventing their unwanted combustion for safety reasons

Flash Ignition of Freestanding Porous Silicon Films: Effects of Film Thickness and Porosity

We report the first successful xenon flash ignition of freestanding porous Si films in air. The minimum flash ignition energy (<i>E</i>_min) first decreases and then increases with increasing the porous Si film thickness due to the competition between light absorption and heat loss. The <i>E</i>_min is lower for higher porosity film because high porosity reduces both the heat capacity and the thermal conductivity, facilitating the temperature rise. These results are important for initiating controlled porous Si combustion and preventing their unwanted combustion for safety reasons

Flash Ignition of Freestanding Porous Silicon Films: Effects of Film Thickness and Porosity

We report the first successful xenon flash ignition of freestanding porous Si films in air. The minimum flash ignition energy (<i>E</i>_min) first decreases and then increases with increasing the porous Si film thickness due to the competition between light absorption and heat loss. The <i>E</i>_min is lower for higher porosity film because high porosity reduces both the heat capacity and the thermal conductivity, facilitating the temperature rise. These results are important for initiating controlled porous Si combustion and preventing their unwanted combustion for safety reasons

Stabilizing Silicon Photocathodes by Solution-Deposited Ni–Fe Layered Double Hydroxide for Efficient Hydrogen Evolution in Alkaline Media

An important pathway toward cost-effective photoelectrochemical (PEC) solar water-splitting devices is to stabilize and catalyze silicon (Si) photocathodes for hydrogen evolution reaction (HER), especially in alkaline solutions. To date, the most stable Si photocathode in alkaline media is protected by the atomic layer deposited (ALD) dense TiO₂ layer and catalyzed by noble metal-based catalysts on top. However, the ALD process is difficult to scale up, and the noble metals are expensive. Herein, we report the first demonstration of using a scalable hydrothermal method to deposit earth-abundant NiFe layered double hydroxide (LDH) to simultaneously protect and catalyze Si photocathodes in alkaline solutions. The NiFe LDH-protected/catalyzed p-type Si photocathode shows a current density of 7 mA/cm² at 0 V vs RHE, an onset potential of ∼0.3 V vs RHE that is comparable to that of the reported p–n⁺ Si photocathodes, and durability of 24 h at 10 mA/cm² in 1 M KOH electrolyte

Sol-Flame Synthesis: A General Strategy To Decorate Nanowires with Metal Oxide/Noble Metal Nanoparticles

The hybrid structure of nanoparticle-decorated nanowires (NP@NW) combines the merits of large specific surface areas for NPs and anisotropic properties for NWs and is a desirable structure for applications including batteries, dye-sensitized solar cells, photoelectrochemical water splitting, and catalysis. Here, we report a novel <i>sol-flame</i> method to synthesize the NP@NW hybrid structure with two unique characteristics: (1) large loading of NPs per NW with the morphology of NP chains fanning radially from the NW core and (2) intimate contact between NPs and NWs. Both features are advantageous for the above applications that involve both surface reactions and charge transport processes. Moreover, the sol-flame method is simple and general, with which we have successfully decorated various NWs with binary/ternary metal oxide and even noble metal NPs. The unique aspects of the sol-flame method arise from the ultrafast heating rate and the high temperature of flame, which enables rapid solvent evaporation and combustion, and the combustion gaseous products blow out NPs as they nucleate, forming the NP chains around NWs

The vascular ultrasound of group 2 and group 3 in different weeks.

<p>Legend: (A) and (C): group 2 at week 12 and week 24; (B) and (D): group 3 at week 12 and week 24.</p

The immuohistochemical staining of atherosclerosis in the 3 groups.

<p>Legend: Magnifications: ×400. MMP-9: matrix metalloproteinase-9; LOX-1: lectin-like oxidized low density lipoprotein receptor-1. Representative pictures of MMP-9 and LOX-1 expressions immuohistochemical staining in the aortic atherosclerotic plaque of the three groups.</p

The H&E staining of atherosclerosis in the three groups.

<p>Legend: Magnifications: ×200(A–C2), ×400(C3). A: Normal aorta intima in group 1. B1–B2: Atherosclerotic plaque in group 2. The endothelial cells shed, numerous foam cells and cholesterol crystal (B1); cell necrosis and calcium deposition (B2). C1–C3: Atherosclerotic plaque in group 3. plaques with thin fibrous caps and big lipid cores (C1), the discontinuous fiber cap (C2), inflammatory cells (C3).</p

The intima with Oil Red O staining of atherosclerosis in the three groups.

<p>The intima with Oil Red O staining of atherosclerosis in the three groups.</p

SI values in the three groups (mean [SD]).

<p>LDL-C: low-density lipoprotein cholesterol, SI: smoothness index, TC: total cholesterol.</p><p>*: <i>P</i><0.01,</p>c<p>: compared with group 1,</p>d<p>: compared with group 2.</p