Silicon is widely recognized as one of the most promising anode materials for lithium-ion batteries due to its 10 times higher specific capacity than graphite. Unfortunately, the large volume change ...of Si materials during their lithiation/delithiation process results in severe pulverization, loss of electrical contact, unstable solid–electrolyte interphase (SEI), and eventual capacity fading. Although there has been tremendous progress to overcome these issues through nanoscale materials design, improved volumetric capacity and reduced cost are still needed for practical application. To address these issues, we design a nonfilling carbon-coated porous silicon microparticle (nC-pSiMP). In this structure, porous silicon microparticles (pSiMPs) consist of many interconnected primary silicon nanoparticles; only the outer surface of the pSiMPs was coated with carbon, leaving the interior pore structures unfilled. Nonfilling carbon coating hinders electrolyte penetration into the nC-pSiMPs, minimizes the electrode–electrolyte contact area, and retains the internal pore space for Si expansion. SEI formation is mostly limited to the outside of the microparticles. As a result, the composite structure demonstrates excellent cycling stability with high reversible specific capacity (∼1500 mAh g–1, 1000 cycles) at the rate of C/4. The nC-pSiMPs contain accurate void space to accommodate Si expansion while not losing packing density, which allows for a high volumetric capacity (∼1000 mAh cm–3). The areal capacity can reach over 3 mAh cm–2 with the mass loading 2.01 mg cm–2. Moreover, the production of nC-pSiMP is simple and scalable using a low-cost silicon monoxide microparticle starting material.
Abstract
In this work, the behavior of the luminescence of mesoporous silicon under irradiation with a femtosecond IR laser is shown by the method of multiphoton microscopy. It was demonstrated that, ...along with the background photoluminescence of porous silicon, bright photoluminescence centers appear on the layer surface, and under certain conditions. Centers with a different, shorter-wavelength emission spectrum also appear.
Hydrogen is an active substitute for current commercial fuels as a green energy source. However, the progress toward hydrogen economy is stalled due to a lack of efficient and economical storage ...systems usually restrained by the material used. Some specific issues still need to improve in recent practical hydrogen storage methods: low surface area, limited capacity to attract gas adsorbate, high-temperature medium for hydrogen desorption, and extreme reactivity towards Oxygen and air. The paper presents a study on the surface modification of silicon nanostructures (SiNSs) synthesized by chemical etching, followed by structure optimization to enhance the hydrogen storage capacity. The standard anodization method prepares porous silicon (PS) while metal-assisted chemical etching fabricates Si and Porous Si nanowires (PSiNWs) on Si and PS substrates. Morphological features like surface area and porous nature were evaluated using SEM, AFM, and BET to interpret the gas-surface interaction. The modified surface area and average roughness of SiNSs increase maximum to 437 m2 g−1 and 501 nm, respectively. The PS shows the highest gas-surface interaction (up to 86.6%) and surface energy due to uniform pore distributions and high surface area. The NMR and FTIR investigate the hydrogen termination on the surface, whereas TG-DSC indicates the desorption of surface hydrides at ∼290 °C. A rank matrix is constructed considering various adsorption-desorption and fabrication parameters to select optimized SiNS, whereas PS is selected as a suitable candidate for hydrogen storage.
•Electrochemical anodization and metal-assisted chemical etching fabricate porous silicon and porous Si nanowires.•The gas physisorption improves in nanopores due to the overlap of attractive fields from adjacent pore walls.•High resistivity substrate Si nanostructures exhibit uniform and homogeneous pore size distribution.•Continuous water rinsing on the hydrogenated surface of Si nanostructures causes hydrogen desorption from the surface.•Porous silicon stands prominently and has a high potential for hydrogen storage based on the rank matrix.
Wound management remains a great challenge for clinicians due to the complex physiological process of wound healing. Porous silicon (PSi) with controlled pore morphology, abundant surface chemistry, ...unique photonic properties, good biocompatibility, easy biodegradation and potential bioactivity represent an exciting class of materials for various biomedical applications. In this review, we focus on the recent progress of PSi in the design of advanced sensing and delivery systems for wound management applications. Firstly, we comprehensively introduce the common type, normal healing process, delaying factors and therapeutic drugs of wound healing. Subsequently, the typical fabrication, functionalization and key characteristics of PSi have been summarized because they provide the basis for further use as biosensing and delivery materials in wound management. Depending on these properties, the rise of PSi materials is evidenced by the examples in literature in recent years, which has emphasized the robust potential of PSi for wound monitoring, treatment and theranostics. Finally, challenges and opportunities for the future development of PSi-based sensors and delivery systems for wound management applications are proposed and summarized. We hope that this review will help readers to better understand current achievements and future prospects on PSi-based sensing and delivery systems for advanced wound management.
Porous silicon-based sensing and delivery systems show great potential in wound management applications including monitoring, treatment and theranostics. Display omitted
Abstract
n and p types of porous silicon were fabricated using two methods electrochemical etching EC and photo-electrochemical etching PEC. Structural studies of both types of porous silicon were ...carried out by X-Ray Diffraction XRD getting 24.5 nm crystallite size in p-PSi and 28.05 nm in n-PSi, AFM, Fourior-Transformation InfraRed FT-IR.
Gibberellins are commonly used as a plant growth regulator in crops, and their excessive use will cause certain harm to human health. Therefore, the detection of gibberellins is of great significance ...to food safety. In this paper, a method based on porous silicon microcavity (PSMC) fluorescence images is proposed for the fast and convenient detection of gibberellins. We experimentally demonstrate that the PSMC has a stronger enhancement on the quantum dots (QDs) fluorescence than the porous silicon Bragg mirror (PSBM). A PSMC photonic crystal sensor was prepared to detect gibberellins in combination with the digital image method. The gibberellin antibody was labeled with carboxyl water-soluble CdSe/ZnS QDs as a fluorescent marker, which reacted specifically with the gibberellin antigen immobilized on the porous silicon (PS) inner wall, Finally, a digital microscope was used to capture a fluorescence image of the PSMC surface. Gibberellins were detected by calculating the average change in gray value between the images taken before and after the immunoreaction. The detection limit of the method for gibberellins is 20.05 pg/mL.
Porous silicon nanowires have been well studied for various applications; however, there are only very limited reports on porous silicon nanowires used for energy storage. Here, we report both ...experimental and theoretical studies of porous doped silicon nanowires synthesized by direct etching of boron-doped silicon wafers. When using alginate as a binder, porous silicon nanowires exhibited superior electrochemical performance and long cycle life as anode material in a lithium ion battery. Even after 250 cycles, the capacity remains stable above 2000, 1600, and 1100 mAh/g at current rates of 2, 4, and 18 A/g, respectively, demonstrating high structure stability due to the high porosity and electron conductivity of the porous silicon nanowires. A mathematic model coupling the lithium ion diffusion and the strain induced by lithium intercalation was employed to study the effect of porosity and pore size on the structure stability. Simulation shows silicon with high porosity and large pore size help to stabilize the structure during charge/discharge cycles.
We studied the influences of the thickness of the porous silicon layer and the conductivity type on the porous silicon sensors response when exposed to ethanol vapor. The response was determined at ...room temperature (27 ∘C) in darkness using a horizontal aluminum electrode pattern. The results indicated that the intensity of the response can be directly or inversely proportional to the thickness of the porous layer depending on the conductivity type of the semiconductor material. The response of the porous sensors was similar to the metal oxide sensors. The results can be used to appropriately select the conductivity of semiconductor materials and the thickness of the porous layer for the target gas.
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