FESEM surface morphology and the schematic illustration of porous silicon filled Pd decorate SiC nanocauliflowers thin film sensor with Ag paste contacts.
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•Pd decorated SiC ...nanocauliflowers (NCs) thin film have been directly fabricated on porous silicon substrates using reactive DC co-sputtering technique.•Hydrogen sensing properties Pd/SiC nanocauliflowers sensor have been investigated.•Pd/SiC NCs sensor exhibits the high response with fast response/recovery towards (5–500) ppm H2 gas at relatively high temperature regime (40–500 °C).
In this work, we have fabricated the Pd decorated silicon carbide (SiC) nanocauliflowers (NCs) thin films on electrochemically etched porous silicon (PS) substrate by DC magnetron co-sputtering technique. The gas sensing performance of Pd/SiC NCs to hydrogen gas under low (5–500 ppm) detection limit at high operating temperature regime (40–500 °C) were studied in detail without additional processing. The nanocauliflowers sensor demonstrates the high sensing response (Ra/Rg ̴ 14.48), fast response/recovery time (10s/18s) with excellent stability (24 cycles) towards 100 ppm H2 at high temperature of 380 °C. The underlying sensing mechanism behind the notable performance of the proposed sensing action towards H2 was also discussed in detail. Therefore, the investigated Pd/SiC NCs can be used as highly sensitive and selective hydrogen gas sensor at high working temperatures in harsh environment.
A new biomimetic nanoreactor design is presented based on cancer cell membrane material in combination with porous silicon nanoparticles. This cellular nanoreactor features a biocompartment enclosed ...by a cell membrane and readily integrated with cells and supplementing the cellular functions under oxidative stress. The study demonstrates the impact of the nanoreactors on improving cellular functions with a potential to serve as artificial organelles.
The use of porous silicon (PSi) as a sensor for detection of various analytes is reviewed. The optical or electrical properties of PSi are key sensing parameters that have been used in many chemical ...and biological sensing applications. PSi is a promising candidate due to ease of fabrication, large surface area, various accessible pore sizes and morphologies, controllable surface modification and its compatibility with conventional silicon processing technology. The adsorption of chemical or biological molecules into the pores modifies the electrical and/or optical properties, allowing convenient and sensitive measurement approach. In this review, we provide a critical assessment of the development of PSi as a promising material for chemical and biosensing applications. Formation procedures of PSi with various pore sizes and morphologies are firstly given. Surface properties and structural characteristics of the material are briefly described. The recent progress on utilization of such porous structures in chemical and biosensing applications is then addressed in the context of surface chemistry effects and nanostructures, measuring approaches, operating concepts and device sensitivity and stability. Finally, concluding remarks with existing challenges that hinder the material for commercial use are highlighted.
This study introduces a novel application of a plasmonic microdisk resonator as a highly sensitive sensor for detecting methanol vapor. Leveraging the inherent advantages of plasmonic nanostructures, ...the microdisk resonator demonstrates a remarkable capability to detect minute concentrations of methanol. In this work, we modeled a novel 3-D porous-silicon (p-Si)-based hybrid plasmonic aperture-coupled microdisk resonator (HPACMR) with specific dimensions and porosity to optimize the sensitivity toward methanol vapor detection. The resonator's design incorporates a thin layer of copper on a dielectric microdisk, creating a plasmonic cavity that supports localized surface plasmon resonances. Finite element method-based simulations predict strong interactions between the resonator's plasmonic field and methanol molecules, leading to detectable shifts in the resonant frequency. By tuning the layout dimensions and p-Si properties, we achieved an altitudinous sensitivity of 569.52 nm/RIU and a Q-factor of nearly 370. The sensors' miniature footprint and potential for integration into portable devices make it an attractive candidate for field-deployable applications.
•The p-Si@VG structure was prepared by fluidized bed chemical vapor deposition (FBCVD) method as anode for LIBs.•The core-shell structure suppresses the volume expansion of Si microparticles.•The ...vertical graphene structure enhances the Li+ diffusion and storage capability.•The p-Si@VG composite exhibits excellent reversible capacity and stable cycle performance.
Silicon is capable of delivering a high theoretical specific capacity (4200 mAh g-1) in lithium-ion batteries. However, silicon has poor electrical conductivity, huge volume expansion (∼300%), and unstable solid electrolyte interface (SEI) film, especially for micron-sized silicon particles. We proposed and prepared a novel vertical carbon (VG) coating on a porous silicon (p-Si) microparticle structure, which effectively alleviated the volume expansion and inhibited the interface reaction. The synthesized porous silicon p-Si@VG composite exhibited significant enhanced cycling stability and an excellent reversible capacity of 1563 mAh g-1 (capacity retention of 48.6%) after 200 cycles. The vertical carbon nanosheet structure constructed a three-dimensional conductive network. Therefore, the p-Si@VG composite showed better rate capability and higher lithium-ion diffusion rates. This work is expected to promote the application of micron Si-based composites in lithium-ion batteries.
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Abstract
Metal-ceramic composite particles are of increasing interest due to their potential applications in photodetectors as well as next-generation catalysts. The zirconium-gold system has ...received little attention due to the lack of controllable preparation methods. Well-known methods for the deposition of gold Nano shells on zirconium spheres, however, should be adaptable for similar zirconium-based materials. Here, we present a method to synthetic approach to the well-controlled deposition of gold on the surface by laser ablation. The results shed light on the parameters governing the preparation of zirconium _ gold composite particles and our synthetic approach provides a promising tool for future developments in complex nanomaterials design. As well as studying the structural and optical properties of gold, silver and zirconium nanoparticles by preparing those particles in the above method and studying the properties of the resulting materials as a photodetector. The surface morphology, structure, and composition of the layer were studied using a variety of spectroscopic diffraction and real-space imaging techniques, including SEM, EDX and AFM.
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•The gas sensing properties of two different types of porous silicon (PS) prepared by a simple chemical method namely nano-porous silicon (nano-PS) and macro-porous silicon (macro-PS) ...are studied.•The porous silicon-based sensors are sensitive to NO2 at room temperature.•Macro-PS sensor shows higher sensitivity to low concentration of NO2, while nano-PS sensor has better response-recovery characteristics.
In this work, we investigate the use of a new low-cost gas sensor based on porous silicon to detect low concentration of NO2 at room temperature. In this work, we focused on the gas sensing properties of two different types of porous silicon (PS) prepared by a simple chemical method namely nano-porous silicon (nano-PS) and macro-porous silicon (macro-PS). The prepared sensors are characterized by different pores size, thicknesses and porosity. Electronic properties of the synthesized structures were studied by measuring the effective minority carrier lifetime using a µPCD lifetime tester. Structural properties and morphology of PS samples were also presented using Fourier transforms infrared (FTIR) spectroscopy and scanning electron microscope (SEM). The gas sensing properties of nano-PS and macro-PS were performed at room temperature for NO2 gas. Macro-PS and nano-PS sensors exhibit different behaviors attributed to the difference in their morphologies. The tested sensors exhibit considerable sensitivity at room temperature to low concentration of NO2 (4 ppm) during response time up to 45 s.
As a most promising anode candidate, silicon has the shortcomings of low electron conductivity and high volume expansion of 300%, hindering its applications in lithium ion batteries (LIBs). In this ...study, one-dimension porous silicon nanowires (pSi-NWs) were prepared through a simple metal-assisted chemical etching process by using metallurgical silicon as raw material. To consolidate the structural integrity of pSi-NWs, a crossed carbon skeleton (c-Cs) was introduced into pSi-NWs via in-situ polymerization and carbonization process. The resultant pSi-NWs@c-Cs composite delivered the high capacity of 1253 mAh g−1 with good cycling stability as well as the notable rate capability (476 mAh g−1 at 4 A g−1), much superior to those of pSi-NWs and pSi-NWs@reduced graphene oxide composite. The enhanced electrochemical performance of pSi-NWs@c-Cs composite is attributed to the crossed carbon skeleton in constructing the advanced Si/C interface to more effectively improve the electron conductivity of pSi-NWs and acting as the protective shell to keep the structure integrity of pSi-NWs. As the additive of commercial graphite anode, 28% of capacity augment (460 mAh g−1 at 0.2 A g−1) was realized by adding 20 wt% of pSi-NWs@c-Cs composite into graphite, demonstrating its promising applications in LIBs.
Plasmonics silver and palladium bimetallic alloy nanoparticles ((Ag@Pd)NPs) within gradient porosity silicon (GPSi) layer were prepared and investigated successfully as an efficient surface enhanced ...Raman scattering (SERS) active substrates. The GPSi was fabricated by dynamic etching process using CW, 405 nm, laser diode with a steady decrease of the etching current density from 80 mA/cm2 to 10 mA/cm2 with eight steps for an etching period of 2 min per step. Bimetallic alloy nanoparticles were prepared by ion reduction process. This was attained by immersing the GPSi in a salt solution containing AgNO3 and PdCl2; mixed at equal ratio for immersing time about 60, 120, 180, and 240 s. The bimetallic alloy SERS active substrates for bacterial detection as a function of immersion time were explored by using Field emission scanning electron microscopy, X-Ray diffraction and Fourier transform infrared spectroscopies and Raman measurements. Efficient SERS active substrates were achieved with a uniform and dense aggregation of nanoparticles on bacterial cells by controlling the immersion times. Aggregated bimetallic alloy nanoparticles into GPSi achieved a SERS enhancement factor (EF) 2.1 × 103, 8.6 × 104, 2.3 × 105, and 5.4 × 104 with 60, 120, 180, and 240 s immersion time, respectively for detecting an ultra-low concentration of about 1 Cfu/ml.
•Synthesis of well-controlled porous Si (PSi) morphology for Plasmonics (Ag@Pd)NPs formation.•Efficient method to controlling plasmonics (Ag@Pd)NPs sizes and hotspots regions.•Easy fabrication way for ((Ag@Pd)NPs/GPSi) bimetallic hetero structures for pathogenic bacteria detection.•Well-organized and controlled SERS technique for detecting an ultra-low concentration of about 1 Cfu/ml.
It is unquestionable that Si nanostructures i.e., nanosheets, nanowires, nanoparticles become more and more importance in high-energy lithium ion batteries (>300 Wh kg−1). However, the current ...commercial Si nanostructures are rather expensive, which is not yet able to complete with the graphite anode in term of USD/Wh kg−1. Herein, the conventional food grade non-porous silicon dioxide (SiO2) which costs 270-times lower than Si micron-sized and 3000-times lower than Si nano-sized (10 nm) is selected as a precursor for synthesizing pure crystalline Si nanoparticles. A novel scalable solvent-free mechanofusion method was firstly introduced to synthesize carbon nanospheres-encapsulated SiO2 (SiO2@C) followed by the reduction process producing silicon-carbon nanoparticles core-shell materials (Si@C) with interparticle void space. The carbon shell can prevent the volume expansion (>400%) of inner Si particles, which is a critical drawback of Si anode. In addition, the pre-lithiated Si@C anode obtained by a direct contact with Li counter electrode can address the poor coulombic efficiency at the first cycle. The pre-lithiated Si@C anode can deliver a reversible discharge specific capacity of 1390 mAh g−1 with a remarkable capacity retention of 90.4% and coulombic efficiency of ∼100% after 1000 cycles at a high rate of 1C. The ex situ TEM and XPS investigated confirm that the inner Si is well-confined within carbon buffer shell without being directly exposed to the electrolyte. Besides, an in operando XRD shows the reversible phase transformation during cycling for which Li15Si4 alloy is the product indicating that Si@C prepared in this work may be an ideal practical anode of high-energy Li-ion batteries.
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•High-energy anode of carbon nanospheres-encapsulated silicon nanostructures.•A novel scalable solvent-free mechanofusion method.•Prelithiated Si@C anode can deliver a reversible specific capacity of 1380 mAh g−1.•Ex situ TEM and XPS confirm the inner Si well-confined within carbon buffer shell.•In operando XRD shows the reversible phase transformation during cycling.
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