Search

In this work, we implemented an off-axis digital holographic microscopy (DHM) setup to study the behavior of liquid drops on nanostructured porous silicon (PS) membranes. When a liquid comes into contact with the PS structure, capillary action and surface tension give rise to imbibition of the liquid into the intricate volume of the pores. At the same time, the vapor field developed around the drop enhances liquid condensation and evaporation into and from the pores. The complex interplay between these phenomena (capillary driven internal flows, condensation, and evaporation) is not yet fully understood but the methods we propose can provide new insights. We demonstrate how DHM allows determining the filling fraction of the porous membrane around drying drops of water and isobutyl alcohol. The phase information obtained from registered holograms provides quantitative information that permits to reconstruct the filling fraction along the porous membrane and its evolution during the drying process. Additionally, relevant parameters such as speed and contact angle during retraction of the drops can be measured. These methods can be further extended to other porous materials, such as porous alumina, micro- and macro-PS, to develop better fluid-dynamic models for describing fluid behavior in highly confined structures. [ABSTRACT FROM AUTHOR]

Porous silicon (Psi) has recently attracted considerable attention because of its unique optical and structural properties and capacity to be used in various applications. Due to the importance of this material, we have investigated the infiltration of trivalent erbium ions (Er3+) into silicon-generated pores using the electrochemical approach. The infiltration of Er3+ ions will be done simultaneously with the forming of porous silicon films on p-type (100) silicon substrates. Generating the porous layer can improve the evenness and integration of Er inside the material. During infiltration, Er3⁺ ions can also undergo reduction or co-deposition with other elements at the cathode. The infiltration studies were conducted while subject to the influence of the current density (15–30 mA/cm2). The results showed that the emission of photoluminescence in porous silicon filled with erbium was caused by the presence of Er silicate and Er oxide that developed within the silicon pores during the electrochemical reaction. The reason for introducing rare earth ions is their exceptional optical characteristics, encompassing distinct emission lines and extended lifespan. We comprehensively investigate infiltration and outline the electrochemical etching parameters necessary to create porous silicon. Rare earth ions exhibit exceptional optical luminescence characteristics, displaying a diverse spectrum of optical spectra over the infrared, visible, and ultraviolet regions. [ABSTRACT FROM AUTHOR]

Hierarchically porous silicon carbide (SiC) is an important catalyst support widely used in various gas and liquid catalytic processes. Conventional approaches to fabricate such SiC have limited design flexibility and separated catalyst‐loading step is necessitated. Herein, a one‐step, direct vat‐photopolymerization 3D printing of hierarchically porous SiC loaded with Co/Ni based catalyst is demonstrated with Pickering emulsion as feedstock for the first time. Compared with normal ceramic slurries, Pickering emulsion dramatically increases the cure depth (by 50%) and emulsion stability, which allow continuous printing of complex SiC structures with uniform pore morphology. The resultant hierarchical porous SiC offered ≈40% better mechanical strength as compared with non‐hierarchical counterpart. By dissolving metal salts into aqueous phase in Pickering emulsions, complex architected structures with Co or Ni/Co in situ loaded in SiC matrix are printed. The metal salts are then thermally converted into oxides or silicates as catalysts anchored on SiC, exhibiting excellent catalytic activity and reusability. The emulsion templating strategy holds great facility to load various highly attractive materials such as high entropy oxides or functional fillers whilst reaping the benefits of vat photopolymerization for a myriad of applications in catalysis, batteries, and structural supports. [ABSTRACT FROM AUTHOR]

A contribution of free charge carriers in an ensemble of anisotropic silicon nanocrystals to the optical properties in the infrared region has been numerically analyzed. Utilizing a generalized effective medium model that accounts for the shape anisotropy of silicon nanocrystals and mobile charge carriers the reflectance, absorption, and transmittance were found to be strongly dependent on the concentration of free charge carriers. For charge carrier (hole) concentrations ranging from 10 16 to 10 20 c m - 3 , significant birefringence and linear dichroism (absorption anisotropy) are observed, along with a non-monotonic dependence of the refractive index and transmittance coefficients for perpendicular polarization directions. The simulation results align well with experimentally measured transmittance spectra of in-plain anisotropic porous silicon films prepared electrochemically from heavily boron-doped (110)-oriented crystalline silicon wafers. Furthermore, the obtained results are discussed in view potential applications in all-silicon based optical switches and modulators and other active elements of the silicon photonics. [ABSTRACT FROM AUTHOR]

Compared to nanostructured Si/C materials, micro-sized Si/C anodes for lithium-ion batteries (LIBs) have gained significant attention in recent years due to their higher volumetric energy density, reduced side reactions and low costs. However, they suffer from more severe volume expansion effects, making the construction of stable micro-sized Si/C anode materials crucial. In this study, we proposed a simple wet chemistry method to obtain porous micro-sized silicon (μP-Si) from waste AlSi alloys. Then, the μP-Si@carbon nanotubes (CNT)@C composite anode with high tap density was prepared by wrapping with CNT and coated with polyvinylpyrrolidone (PVP)-derived carbon. Electrochemical tests and finite element (FEM) simulations revealed that the introduction of CNTs and PVP-derived carbon synergistically optimize the stability and overall performance of the μP-Si electrode via construction of tough composite interface networks. As an anode material for LIBs, the μP-Si@CNT@C electrode exhibits boosted reversible capacity (∼ 3500 mAh·g−1 at 0.2 A·g−1), lifetime and rate performance compared to pure μP-Si. Further full cell assembly and testing also indicates that μP-Si@CNT@C is a highly promising anode, with potential applications in future advanced LIBs. It is expected that this work can provide valuable insights for the development of micro-sized Si-based anode materials for high-energy-density LIBs. [ABSTRACT FROM AUTHOR]

In response to the water contamination problem, this study presents a novel method to remove methylene blue (MB), a typical water pollutant, using synthesized porous silicon dioxide (SiO2). The SiO2 was synthesized via a cost-effective sol–gel method and characterized for its thermal stability, structural, textural, morphological properties, and elemental composition using techniques such as TGA, FT-IR, XRD, BET-BJH, SEM, TEM, and STEM-EDS. A unique aspect of this study is the evaluation of SiO2 reusability in MB removal through multiple adsorption and thermal regeneration cycles, a critical factor for practical applications. The results demonstrated the successful synthesis of thermally stable, amorphous, porous SiO2 with a surface area of 811 m2g−1 initially, reducing to 600 m2g−1 after the adsorption and regeneration cycles, indicating its stability and durability. The removal efficiency of MB was consistent across cycles, achieving 71.19 ± 0.94%, 75.55 ± 0.69%, and 73.49 ± 0.15% after 20 min, and the adsorption capacity at equilibrium was 3.73 ± 0.025, 4.08 ± 0.045, and 3.48 ± 0.021 mgMB gads−1 during the first, second, and third cycles, respectively. These findings highlight the potential of the synthesized porous SiO2 as a reusable and efficient adsorbent for MB removal in water treatment, contributing to the advancement of sustainable and effective solutions for water pollution. [ABSTRACT FROM AUTHOR]

Escherichia coli (E. coli) bacteria identification is important in many areas, such as environmental monitoring and medical diagnostics. Conventional techniques frequently lack specificity and sensitivity. This study investigates the fabrication and characterization of a high-sensitive E. coli bacteria sensor using mesoporous silicon prepared by an electrochemical etching process under different low current densities. This study explores a high-sensitive E. coli sensor grown in nutrient agar at 36.5 °C, deposited on the mesoporous silicon surface, with morphology analyzed using scanning electron microscopy (SEM) and current–voltage characteristics measured. The XRD analysis confirmed the peaks of silicon material with a polycrystalline nature. FTIR demonstrated Si–H bonds which approve the porosity process. Results indicated that silicon etched at 3 mA/cm2 had small slit mesopores and large nanoparticles (73–102 nm) and at 9 mA/cm2, the smallest non-aggregated nanoparticles (54–83 nm) and largest pores (20 nm) were achieved. This study concludes that mesoporous silicon etched at 9 mA/cm2 provides the best performance for E. coli detection, demonstrating its potential for high-quality biosensor applications. [ABSTRACT FROM AUTHOR]

The physical properties of porous silicon (PSi) can be adjusted to provide a better performance in optoelectronic devices. A controlled method commonly used to fabricate PSi is the anodization process, which employs platinum as a conventional cathode. Herein, we investigate the effect of replacing the Pt cathode with symmetric heavily doped silicon on the resulting surface structure on silicon substrates. The symmetric configuration is established when both anode and cathode are from the same material. Three different samples were anodized using both configurations and under different fabrication conditions. The results demonstrate the possibility to produce porous silicon structure using the heavily doped Si as alternative to the expensive Pt counter electrode. Furthermore the modified configuration offers the possibility of manufacturing large areas of nanostructured PSi without limitation of the counter electrode area and the applied current density. The formed porous structures using Si cathode have better uniformity, larger pore size, and lower number of interlinked and shallow holes than traditional methods. The porous structures fabricated with this configuration show broadband reduction in spectral reflectivity and changes in the schottky diode dark characteristics when compared with PSi fabricated with Pt conventional electrode. [ABSTRACT FROM AUTHOR]

Nanostructured silicon is a promising material for many recent applications. In this work, inverted pyramidal porous silicon is synthesized by two stages metal assisted etching followed by PECVD rebuilding. At first, nanowires are obtained by conventional Ag assisted chemical etching at the surface of monocrystalline silicon wafer. Then, Inverted pyramidal (IP) macroporous structure is obtained by dipping the sample in HNO3: Ni solution after nanowire harvesting. Finally, PECVD is used to build deep holes on the porous surface template. The depth of the pyramidal holes can be tuned by deposition time and silane pressure. The macroporous structure characteristics are investigated by many techniques such as XRD, SEM, FTIR, reflectivity and impedance. Sensing tests of IP layers for different gases show their selectivity for NO2. Highlights: - PECVD growth of amorphous silicon on pyramidal porous surface leads to inverted pyramidal (IP) structure with deep pores. The depth can be tuned by PECVD deposition time. - Amorphous layer deposited by PECVD uses textured surface as pattern. - Dipping silicon nanowires in Ni:HNO3 leads to their harvesting and to shallow pyramidal pores at Si surface. - Grazing incident XRD patterns and FTIR spectra show the presence of nickel silicide nanoparticles at the surface of amorphous layer. These nanoparticles play a key role in the formation of IP pores. - Impedance analysis shows that main transfer mechanism is the hoping of charges between localized states induced by nickel silicides. - Gas detection measurements show the capability of our IP samples as selective gas sensor for NO2. [ABSTRACT FROM AUTHOR]

Deoxyribonucleic Acid (DNA) chip technology is of interest in the development of diagnostic devices and drug delivery applications. Silicon has been widely used for the fabrication of micro-electro-mechanical system (MEMS) and smart sensors, which are now commercially available. The aim of this work is to develop a sensor or chip for specific DNA sequences. The high sensitivity of the biochip is achieved by increasing the specific surface area of the device. Nanostructured porous silicon has high surface area that can be prepared to have large variety of pore morphologies by electrochemical etching of silicon wafer. In the present work, the immobilization of single stranded DNA and its hybridization on modified porous silicon as well as on flat silicon surface has been demonstrated. DNA immobilization on modified silicon surfaces and its subsequent hybridization was studied using gP32 labelled DNA, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectronspectroscopy (XPS). More than 70% of DNA binding was achieved on the porous silicon in comparison to the flat silicon surface which has less than 20% of DNA binding. Enhanced DNA binding on nanostructured porous silicon as compared to flat silicon surface is due to its large surface area and good molecular penetration into its pores. The high fidelity of nanostructured porous silicon surface promises substantial benefit to the emerging technology for nucleic acid-based biosensors and diagnostic chips. [ABSTRACT FROM AUTHOR]

Fasciolosis is an important disease of livestock with increasing reports of human infection, caused by the helminth parasite Fasciola. In this study, we report a preliminary approach towards the development of immunosensors based on nanostructured porous silicon for the detection of Fasciola infection. The surface of porous silicon was biofunctionalized by the deposition of 3-aminopropyltriethoxysilane (APTS) from solution, leading to high density of amine groups covering the surface which would promote the further immobilization of biomolecules like antibodies. The antibody against bacterial collagenase IV binds with porous silicon and its variable region binds with Fasciola gigantica excretory/secretory (ES) products which were then detected by observing the apple green colour under fluorescence microscope by using fluorescein isothiocyanate (FITC) labeled bacterial collagenase IV antibody. In addition the FTIR study was also performed. The present study suggests the possibility of using porous silicon as immunosensors for F. gigantica infection detection with low cost and high sensitivity. [ABSTRACT FROM AUTHOR]

In this work, a photoelectrochemical reactor with an anode based on hybrid structure between conducting polymer polypyrrole (PPy) and porous silicon (PSi) was fabricated and utilized to evaluate the photocatalysis and electro‐assisted photocatalysis for degradation of rhodamine B (RhB) solution. The PSi was made of n‐type silicon single‐crystal wafer by the metal‐assisted chemical etching (MACE). The anode PPy/PSi formed following a polymerization of the PPy on the PSi from the vapour‐phase route using oxidant FeCl3. Typical material characterizations of the PPy, PSi and PPy/PSi were investigated via scanning electron microscope (SEM), and spectroscopies of Fourier‐transform infrared (FTIR), Raman scattering and UV‐vis. Under visible light radiation (halogen light with the wavelength region of 400–700 nm), photocatalytic and electro‐assisted photocatalytic processes of the reactor were conducted by degradation of the RhB solution. A heterojunction (p‐n) of the PPy/PSi was proposed to explain the efficient catalytic performance of the reactor. [ABSTRACT FROM AUTHOR]

In this study, the optical properties of porous silicon (PSi), such as the dielectric function, absorption coefficient, bandgap, reflectivity and refractive index, were studied as a function of porosities ranging from 3% to about 40% by using a supercell model in an ab-initio pseudo-potential plane wave (PP-PW) method based on density functional theory (DFT). To validate these theoretical results, various PSi samples were prepared by varying the etching parameters to achieve similar porosities. The PSi samples were subjected to UV–vis spectrophotometry in order to measure their reflectivity. The refractive indexes predicted by DFT were compared to those obtained by the Fresnel equation and the effective medium approximation methods (EMA), particularly Bruggeman's, Looyenga's and del Rio's model (dRZW). These studies showed that the PSi dielectric constant decreases with increasing porosity, which is consistent with a decrease in the refractive index. In addition, as the porosity of PSi rises, the bandgap energy values increase, which is closely related to the decrease in the refractive index. For low porosity, DFT and Looyenga refractive indexes fit better than dRZW or Bruggeman. Furthermore, when the porosity is increased, DFT gives similar results as dRZW and is better than the Bruggeman method. Moreover, at medium porosity (28 or 40%), DFT and EMA models agree well with the experimental refractive indexes of PSi. [ABSTRACT FROM AUTHOR]

Laser ablation of a porous silicon target irradiated by ultrashort IR laser pulses in an air environment is simulated using the molecular dynamic approach. The number of ablated atoms is calculated for targets with different porosity and pore size. It is found that a porous silicon target with 1 nm pore size is ablated more efficiently at low laser pulse fluences. It is shown that an increase in the target porosity leads to a decrease in the ablation threshold: with a change in porosity from 10 to 50%, the laser ablation threshold decreases by more than 1.5 times. The obtained results can be applied to optimize the regimes of laser ablation synthesis of nanoparticles using nanostructured porous silicon targets. [ABSTRACT FROM AUTHOR]

The field-effect transistors (FETs) based on reduced graphene oxide (rGO) with SiO2, porous silicon (PS), and oxidized porous silicon (PSox) supporting layers were obtained. The influence of charged impurities in the silicon substrate and electrically active defects in the support layers on the electrical properties of the FETs was studied based on the capacitance-voltage characteristic analysis. Localized electron states in the SiO2, PS, and PSox supporting layers that affect the charge transfer in the rGO-based FETs were determined using thermally stimulated depolarization spectroscopy. The influence mechanisms of various supporting layers on the electrical characteristics of the obtained FETs are discussed. [ABSTRACT FROM AUTHOR]

In this study, palladium (Pd) nanoparticles were prepared using a laser ablation method and investigated using XRD, transmission electron microscopy (TEM), microscopic atomic force (AFM), UV-vis, PL, and various We investigated the fabrication of gas sensors with laser energy, Pd nanoparticles were generated by laser ablation in liquid applying a magnetic field with a pulse energy of 660 mJ for 200 shots, and Pd NPs were precipitated onto porous silicon (PS) using a drop casting process. The specimen's nanocrystalline had been revealed by the XRD diffraction pattern. AFM demonstrated a growth in the agglomeration of Pd NPs; the TEM results indicated that the average particle size of Pd particles between 52.44 and 16.07 nm is decreased in presence of magnetic field. Photoluminescence detector electronic properties of energy band gap described increases from 3.16 to 3.44 eV. The sensor sensitivity for NO2 and H2S gas sensors constructed from the prepared material were also examined in relation to temperature changes. For Pd NPs/PS/Si, gas sensors have a maximum sensitivity of around 75.6% at 100 ◦C for sample prepare 660 mJ without magnetic field, but the highest sensitivity in the presence of a magnetic field was 28.72% at 25 ◦C for H2S gas. Additionally, it can achieve maximum sensitivity of Pd NPs/PS/Si at gas sensor to 63.09% and 55.66% in both the presence and absence of a magnetic field for NO2 gas, respectively. Effect of temperature change on reaction time and sensor sensitivity [ABSTRACT FROM AUTHOR]

To overcome the significant volume expansion issue encountered by traditional silicon anodes in lithium‐ion batteries, this study employs chemical etching techniques to treat aluminum–silicon alloys of various ratios, successfully preparing three types of porous silicon electrode materials with different pore structures. Through a series of electrochemical tests, this article investigates the role of porous silicon structures in improving electrode performance. The results demonstrate that the porous silicon anodes exhibit superior cycle stability and rate capability compared to traditional solid silicon anodes. This confirms the effectiveness of the porous structure in mitigating the significant volume expansion during the charge and discharge process of silicon materials and in preventing premature electrode failure, thereby significantly enhancing the electrode's cycle life. Remarkably, the porous silicon with a high porosity rate shows exceptionally outstanding performance. Additionally, using computer simulations, this study also models the impact of changes in pore size within the porous silicon material at different states of charge and discharge on the stress distribution at the particle center and surface. These experimental and simulation results jointly provide strong empirical evidence for applying porous silicon materials as high‐performance anode materials for lithium‐ion batteries and offer essential guidance for future stress analysis and electrode design of porous silicon electrode materials. [ABSTRACT FROM AUTHOR]

Three types of mesoporous silicon flakes were fabricated by anodization in methanoic hydrofluoric acid from the same substrates (heavily doped p-type). Even though anodization current density, rinsing, drying method, and storage condition were the same for all three wafers, the resulting porous silicon (PSi) structures had very different properties. They had very different colors. Two of them showed quite high luminescence quantum yields (QYs), confirmed by very long luminescence lifetimes. The highest QY exceeded 50% for a peak photoluminescence wavelength of ∼750 nm. To date, this QY is the highest obtained for PSi and very importantly for silicon with large mesopores, which is typically not highly efficient (as opposed to silicon with small mesopores and microporous silicon). Large mesopores (>15 nm diameter) facilitate impregnation of various substances into luminescent material, such as metals for plasmonics and drugs for theranostics. The differing luminescent properties were correlated to electrolyte temperature during anodization, and evolution of the electrolyte batch (lowering of active fluoride content and buildup of hexafluorosilicate) used to anodize several wafers, whose effects are often overlooked when mass-producing PSi. Supercritical drying and completion of the slow growth of native oxide passivation in the dark leading to different final partially oxidized PSi structures are also important factors for the high QYs obtained. The highest QY was obtained with the structure having the most isolated Si nanocrystals in an amorphous Si oxide tissue. [ABSTRACT FROM AUTHOR]

The measurement of patients' dosages of radiation caused by medical diagnostics continues to be challenging. A Cantor sequence photonic crystal structure using porous silicon doped with a polymer of polyvinyl alcohol, carbol fuchsin and crystal violet (DPV) is proposed. The influence rules of geometrical and optical parameters such as the radiation doses, number of periods, porosity of porous layers, incident angle and thickness of layers are investigated using MATLAB based on the transfer matrix method. The transmittance of the Cantor sequence of a defective photonic crystal sensor under different conditions is investigated to select the optimum conditions. The proposed system recorded the accepted sensitivity of 0.265 nm/Gy, FoM of 6.5 Gy − 1 , Q of 12,701, RS of 6 × 1 0 − 3 and LoD of 8 × 1 0 − 3 for gamma radiation. The suggested detector has simple design, accurate monitoring efficiency and immense potential for gamma radiation sensing. [ABSTRACT FROM AUTHOR]

A novel PANI/NiCO2O4/CeO2 nanocomposite was prepared using the binary Nano metal oxide NiCo2O4/CeO2 with aniline and ammonium persulfate (APS) via a one-step polymerization and drop throwing system. The nanocomposite was explored by X-ray diffraction (XRD) analysis confirmed the successful integration of nanoparticles into PANI. UV-visible spectroscopy revealed absorbance peaks characteristic of PANI combined with nano metal oxides. Raman spectroscopy further verified the nanocomposite's structure, with peaks at 415, 517, 575, and 640 cm− 1 attributed to CeO2 and NiCo2O4 nanoparticles within the PANI matrix. Field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDX) analyses of the doped PANI showed nanostructures ranging from 18.40 to 23.28 nm. Photodetection properties such as responsivity (Rλ), detectivity (D*), and external quantum efficiency (QE) of porous silicon nanocomposites were assessed using the drop-casting method. The incorporation of Ag/PANI-NiCo2O4-CeO2/PSi/Si/Ag enhanced the ideality factor of porous silicon. At wavelengths of 350–900 nm, the values of Rλ, D*, and QE were measured at 0.37 A/W, 5.3 × 10^12 cmHz^1/2/W, and 110%, respectively. [ABSTRACT FROM AUTHOR]

In this study, a novel gamma-ray radiation sensor has been developed depending on a 1D photonic crystal (1D-PhC). Based on porous silicon (PSi) layer that has been penetrated by a conjugated copolymer (B-co-MP) which consists of BEHP-PPV and MEH-PPV, with a fractional ratio of 60:40. The suggested method for the development of the dosimeter is based on the shift of photonic band-gap to shorter wavelengths, where exposure to gamma-ray radiation at doses ranging from 0 to 20 kGy alters the refractive index of the (B-co-MP) copolymer. The fitted experimental data, the equation of Bruggeman effective medium, and the transfer matrix method (TMM) are the main axes in the framework of the current theoretical approach. The collected data shows that, within the visible range, the suggested sensor's sensitivity (224 nm/RIU) is high and stable over a 0-20 kGy applied-dose range. Also, we compared these results with previous research. [ABSTRACT FROM AUTHOR]

Helicobacter pylori (H. pylori) is a common pathogen with a high prevalence of infection in human populations. The diagnosis of H. pylori infection is critical for its treatment, eradication, and prognosis. Biosensors have been demonstrated to be powerful for the rapid onsite detection of pathogens, particularly for point-of-care test (POCT) scenarios. In this work, we propose a novel optical biosensor, based on nanomaterial porous silicon (PSi) and photonic surface state Tamm Plasmon Polariton (TPP), for the detection of cytotoxin-associated antigen A (CagA) of H. pylori bacterium. We fabricated the PSi TPP biosensor, analyzed its optical characteristics, and demonstrated through experiments, with the sensing of the CagA antigen, that the TPP biosensor has a sensitivity of 100 pm/(ng/mL), a limit of detection of 0.05 ng/mL, and specificity in terms of positive-to-negative ratio that is greater than six. From these performance factors, it can be concluded that the TPP biosensor can serve as an effective tool for the diagnosis of H. pylori infection, either in analytical labs or in POCT applications. [ABSTRACT FROM AUTHOR]

Porous silicon (PSi) has received a lot of attention in nanotechnology research in recent years for its potential use as sensing layers in sensor application. However, there have been relatively limited studies concerning the effect of varying contact gaps and bias voltages on the humidity sensor based on PSi. In this work, the nanostructure PSi layer was synthesized via the anodization method and fabricated at different annealing temperatures of 250 ℃, 450 ℃, 650 ℃, and 850 ℃. Subsequently, the four samples were deposited with varying gold (Au) contact gaps of 3.5 mm, 4.5 mm, 7.5 mm, and 8.5 mm. The morphological and structural characteristics of the PSi layer were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The PSi-based humidity sensors with varied Au contact gaps were evaluated in a humidity chamber at 40–90% relative humidity (RH) levels with different bias voltages of 2 V, 5 V, and 10 V. The optimized fabricated PSi device was evaluated for its electrical behaviour using I-V measurement under various operating temperatures ranging from 25 °C to 100 °C. The findings showed that the enhanced PSi structure of the 450 °C annealed sensor produced the highest sensitivity performance of 18.4705 µA/%RH with stable output at a contact gap of 4.5 mm and a bias voltage of 10 V. The sensor exhibited a high surface area to volume ratio, which facilitated efficient interactions between surface active sites and water molecules, resulting in a highly sensitive humidity sensor. [ABSTRACT FROM AUTHOR]

Solid‐state hydrogen storage using metal hydrides offers the potential for high energy storage capacities. However, the requirement for high‐temperature operations (above 400°C) and challenges with heat exchange are significant drawbacks. From this perspective, adsorption on porous materials presents a viable solution to these challenges. Carbon nanostructures, such as graphene and graphene oxide (GO) derivatives, are well‐suited for hydrogen storage because of their lightweight nature, low density, and large surface area. However, the primary obstacle for practical applications is the poor storage capacity of carbon nanostructures under ambient conditions. Utilizing a cost‐effective transition element such as nickel as a catalyst offers significant potential for storing hydrogen in atomic and molecular forms by invoking the spillover mechanism. Thermally reduced graphene oxide (TrGO) modifies the surface, providing abundant active sites that attract hydrogen effectively. Porous silicon (PS) enhances the surface properties of graphene sheets, attracting hydrogen to the surface. The current study assesses a synthesized TrGO, PS, and Ni composition to leverage their individual properties for hydrogen storage. Field‐emission scanning electron microscopy examines the sheet structure of TrGO (used as the host material) and the incorporation of PS and Ni on its surface. The calculated specific surface area of TrGO is ~450 m2 g−1. X‐ray diffraction is used to identify the various phases in the composition, while Raman spectroscopy measures the degree of disorder within the composition. The pressure‐composition isotherms reveal hydrogen storage capacities of ~6.53 wt% for the TrGO + PS composition and ~2.43 wt% for the TrGO + PS + Ni composition. Despite the decrease in weight percentage of TrGO + PS + Ni due to the higher Ni content, dissociation enhances the adsorption rate from 0.35 to 0.53 wt% h−1. [ABSTRACT FROM AUTHOR]

This work reports the pore‐filling of porous silicon (PSi) and the loading of silicon nanotubes (SiNTs) with Pt‐Fe nanoparticles (NPs) and the corresponding different magnetic behavior of the two composite systems. The fabrication of magnetic hard/soft nanostructures is in demand for the purpose of achieving both a high energy product as well as the replacement of rare earth permanent magnets. Pt‐Fe templated by PSi shows a higher coercivity and remanence than SiNTs/Pt‐Fe and thus a higher hard magnetic performance, the difference between coercivities being about 57%. Considering that the Pt‐Fe deposits employ different molar ratios of Pt to Fe the coercivities vary in a range of 5% in the case of both template types. Comparing Pt‐Fe loaded samples with Co‐loaded samples in all cases, an increase of the coercivity and the remanence is observed for Pt‐Fe, whereas in the case of PSi as template material the increase is significantly stronger (about twice as much) than in the case of SiNTs samples. Furthermore, the samples are investigated at high temperatures up to 950 K to determine the Curie temperature of the systems. [ABSTRACT FROM AUTHOR]

We describe in this work an evaluation of bundles of hollow mesoporous silicon nanotubes to facilitate transfection of HeLa cells using small interfering RNA designed to knock down expression of Enhanced Green Fluorescent Protein (eGFP). These experiments entail direct visualization of the nanotube bundles associated with the cells using both scanning electron microscopy (SEM) and confocal fluorescence imaging. These nanotube bundles are generated by surface modification of nanotube arrays with aminopropyl‐triethoxysilane (APTES), followed by their ultrasonication in water, to create the amine‐terminated structures capable of electrostatic conjugation of siRNA at an efficiency of 23%–50% (depending on initial siRNA concentration). Delivery and transfection to HeLa cells are verified by quantification of fluorescence imaging; an average percent knockdown of ∼50% eGFP is achieved. As nanoscale drug delivery vehicles are expected to be resorbed in clinical use, we also assess SiNT bundle degradation during the above in vitro timescale using scanning and transmission electron (TEM) microscopies. We conclude with a brief discussion of challenges and opportunities in future experiments involving this platform. [ABSTRACT FROM AUTHOR]

We describe porous silicon nanoparticles (pSiNP) chemically functionalized with an analog of mannose 6‐phosphate (AMFA) and a porphyrin derivative to target aggressive pediatric Rhabdomyosarcoma (RMS) tumor cells. Our findings demonstrate that the pSiNP@AMFA@porphyrin nanosystems are efficiently internalized by RMS cells, which overexpress mannose 6‐phosphate receptors, and induce cytotoxicity and phototoxicity when exposed to two‐photon excitation light. These results provide an interesting potential for targeting and treating RMS pediatric tumors. [ABSTRACT FROM AUTHOR]

There is a global trend of increasing antibiotic resistance to Gram‐negative bacteria and the medical research community is looking for alternative antibiotics. Antibiotics such as polymyxin B (PMB) show excellent efficacy and low resistance rates against Gram‐negative bacteria. The topical administration of PMB, however, has clinical limitations such as minimal residence time, making it difficult for its use to treat skin infections. Here, we present porous silicon microneedle (pSi MN) patches to deliver PMB to the skin. pSi MN patches are fabricated by, first, generating the projections by dry Si etching techniques, followed by an electrochemical etching to create porous layers around the MNs. After loading PMB into the porous layer, the antibacterial activity of pSi MNs is determined by measuring the inhibition zone of Gram‐negative Escherichia coli. Next, PMB is efficiently delivered into the epidermal layer of ex vivo skin models, as confirmed by chemical mapping using matrix‐assisted laser desorption/ionization mass spectrometry imaging (MALDI‐MSI). The results demonstrate that pSi MN patches are an efficient and versatile tool for the transdermal delivery of PMB with maintained bioactivity and antimicrobial efficacy, thus expanding the possibilities of current transdermal drug delivery systems. [ABSTRACT FROM AUTHOR]

Infectious diseases are a global public health concern generated by uncontrolled uses of antimicrobials resulting in multidrug‐resistant (MDR) pathogens. The antimicrobial resistance (AMR) has made explicit the ineffective action of the current medicines and vaccines. Rapid diagnosis and effective treatment are the keys to reduce the capacity of MDR pathogens spreading very fast, avoiding high socioeconomic impact, severe and prolonged illness and death. Advanced porous materials have emerged as promising alternatives to the conventional diagnoses and therapy due to their low‐cost production, high biocompatibility, adjustable porous structure, large surface area, easy surface functionalization and capacity of loading high drugs amount. In this review, we first highlighted the current strategies to fight against infectious diseases. Then, we introduce the main advanced porous materials used in infectious diseases, including mesoporous silica nanoparticles (MSNs), porous silicon nanoparticles (PSiNPs), metal–organic frameworks (MOFs), covalent–organic frameworks (COFs), hydrogen‐bonded organic frameworks (HOFs) and porous carbon materials. The strategies to fabricate these materials and their characterization for the application in the recent years for antimicrobial treatment is also discussed. Finally, we present an overview outlook and challenges on the future application of such materials for infectious diseases. [ABSTRACT FROM AUTHOR]

In a series of measurements, a comparison is made of nonlinear scattering in suspensions of porous silicon nanoparticles in ethanol and bidistilled water. Scattering has a threshold character in terms of the concentration of nanoparticles and the energy of the initiating laser. With a small difference in the sizes of nanoparticles, a significant difference in the nature of scattering spectra and optimal concentrations of suspensions is observed. [ABSTRACT FROM AUTHOR]

In this study, dual-face porous silicon layers (Df-PSi) and hybrid structures with (AuNPs/PSi/Si / PSi /AuNPs) configurations are fabricated and investigated. The Df-Psi layers were synthesized simultaneously using the dual beam laser supporting etching (DB-LSE) route, which employed two identical laser beams. The Df-PSi layers hybrid structures were produced by integrating Au-NPs into PSi in an HAuCl4 solution using a dipping technique. The results showed well-ordered, highly symmetrical Df-PSi and hybrid structures with minute variations in overall characteristics due to a small change in the absorption laser intensity during the etching process. Following the Df-PSi synthesis, hotspot vacancies among nanoparticles in hybrid structures and the size distribution, and specific surface area (SSA) of gold nanoparticles (AuNPs) showed a well-ordered realization. [ABSTRACT FROM AUTHOR]

This work presents the development and design of aptasensor employing porous silicon (PSi) Fabry‒Pérot thin films that are suitable for use as optical transducers for the detection of lactoferrin (LF), which is a protein biomarker secreted at elevated levels during gastrointestinal (GI) inflammatory disorders such as inflammatory bowel disease and chronic pancreatitis. To overcome the primary limitation associated with PSi biosensors—namely, their relatively poor sensitivity due to issues related to complex mass transfer phenomena and reaction kinetics—we employed two strategic approaches: First, we sought to optimize the porous nanostructure with respect to factors including layer thickness, pore diameter, and capture probe density. Second, we leveraged convection properties by integrating the resulting biosensor into a 3D-printed microfluidic system that also had one of two different micromixer architectures (i.e., staggered herringbone micromixers or microimpellers) embedded. We demonstrated that tailoring the PSi aptasensor significantly improved its performance, achieving a limit of detection (LOD) of 50 nM—which is >1 order of magnitude lower than that achieved using previously-developed biosensors of this type. Moreover, integration into microfluidic systems that incorporated passive and active micromixers further enhanced the aptasensor's sensitivity, achieving an additional reduction in the LOD by yet another order of magnitude. These advancements demonstrate the potential of combining PSi-based optical transducers with microfluidic technology to create sensitive label-free biosensing platforms for the detection of GI inflammatory biomarkers. [ABSTRACT FROM AUTHOR]

The effective removal of complex pollutants is extremely challenging for environmental and material science, especially pollutants including detergents and pesticides do not decompose or degrade in the aquatic environment which cannot be easily removed. Here, a novel biocompatible superparamagnetic nanocomposite integrating the advantages of porous silicon nanoparticles is developed, the chelation ability of chitosan, and graphene‐oxide‐iron that can simultaneously adsorb complex hydrophobic and hydrophilic pollutants on their internal and external surfaces which have significantly improved pollutant removal efficiency over the current existing methods. A porous silicon nanoparticle (PSi) conjugated magnetite‐chitosan‐reduced graphene oxide (MCRGO) nanoparticles (PSi‐MCRGO) are synthesized for complete removal of detergent, pesticide, and toxic heavy metals cadmium and lead ions from water at a favorable room temperature. The adsorption behavior of the nanocomposites fits well with the Freundlich isotherm and pseudo‐second‐order kinetics model by adsorption mechanism. Moreover, the fresh and recycled nanocomposites are easily separated by an external magnetic field for reusability due to super magnetite response and show high binding capacity for toxic heavy metal ions. Furthermore, the nanocomposites are biocompatible and reusable, and for the fourth time, recycled nanocomposites can completely remove toxic heavy metals. Overall, the novel nanocomposites completely remove complex pollutants which hold great potential for real water treatment. [ABSTRACT FROM AUTHOR]

The silicon wafer with golden illuminating nanoporous thin film was obtained by anodizing boron doped silicon wafers by provided appropriate electric input of 20 mA/cm2 through Keithley source meter. An increase in anodization time shifts the photoluminescence (PL) spectra to a higher PL emission energy as well as a higher PL emission intensity. The dynamic properties of the photoluminating porous silicon thin film were analyzed for the sample obtained at different etching times. Upon excitation at 410 nm, the photoluminescence exhibited a single-exponential decay signal and the decay time doesn't depend on the etching time. Small differences in decay time at each spot on the etched surface of the same sample show the distribution dependence of nanocrystallite size. Images of the sample fluorescence also show a distribution in brightness. This complex behavior provides evidence that the quantum confinement effect could be playing an important role. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The synthesis of photodetectors for ZnO nanostructure films on various substrates, including p-type (100) silicon (Si), and porous silicon (pSi), has been achieved through the utilization of a straightforward technique known as the successive ionic layer adsorption and reaction (SILAR) method. To analyze the optical properties, surface morphology, and crystal structure of the ZnO layers, UV-Vis spectrometers, field emission scanning electron microscopes (FESEM), and X-ray diffraction (XRD) were employed. The characterization of the ZnO samples revealed that the number of SILAR cycles has a significant impact on the morphology and optical band gap of the synthesized layer. The Fourier-transform infrared (FTIR) spectrum successfully detected the distinctive extended vibration mode of ZnO. By conducting 20 cycles, high-quality hexagonal ZnO was obtained. The responsivity of the planar ZnO on silicon (ZnO/Si) and ZnO on the porous silicon (ZnO/pSi) surface exhibited variations depending on the substrate surface and bias voltage. The results indicated that the (ZnO/pSi) heterojunction demonstrated a high response in the visible range (350–850 nm) at a low bias voltage. On the other hand, the (ZnO/Si) photodetector displayed a high sensitivity of 666.66% at a low voltage of 1V in comparison to the (ZnO/pSi) photodetector, which exhibited a sensitivity of 483%. [ABSTRACT FROM AUTHOR]

In the present work, we used a pulsed laser deposition technique to embed TiO2 nanostructure on porous silicon substrates using a pulsed laser deposition process. Nanocrystalline porous silicon was synthesized using the photo-assisted electrochemical method. The study analyzed the optoelectronic characteristics of double junctions of TiO2/PS/n-Si structures as well as the PS/n-Si structure. We investigated the properties of TiO2/PS/n-Si and PS/n-Si structures, focusing on their structural, optical, and electrical features under ambient conditions. The XRD measurement indicated the formation of the anatase and rutile tetragonal phases with the preferred orientation anatase (101) plane in the prepared sample. The mean sizes of The TiO2 nanostructures deposited onto porous silicon substrates range from 45.97 to 109.23 nm. The degree of pore filling depends upon the laser fluences employed, varying from moderate to close to complete packing. The optical properties of TiO2/PS/n-Si structures showed decreasing reflectance after depositing on porous silicon. The TiO2 nanostructure produced on porous silicon exhibits five different spectra in the UV and visible range, as displayed in the room-temperature photoluminescence analysis. The current density–voltage characteristics of formed samples in dark and photoilluminated conditions are examined at room temperature. The properties of the TiO2/PS/n-Si structure enhance those of the PS/n-Si device. The highest specific detectivity of the TiO2/PS/n-Si devices is 32.45 × 1010 Jones in the visible region, while the ultraviolet region is 30.04 × 1010 Jones. The TiO2/PS/n-Si photodetectors possess an optimal relative quantum efficiency of 80.1% in the near UV region, whereas, in the visible range, the values of relative quantum efficiency are 51.8% at 531 nm and 54.5% at 634 nm. The findings reveal that formed photodetectors exhibit UV and visible light sensitivity after depositing TiO2 layers on porous silicon. However, the photodetectors produced using TiO2 nanostructures placed on porous silicon demonstrate greater sensitivity than those made from as-synthesized porous silicon. [ABSTRACT FROM AUTHOR]

Porous silicon (PSi) is an intriguing material with unusual optical and electrical properties, and researching its temperature-dependent photoluminescence (PL) qualities might provide important insights into its behavior. In this respect, we conducted a thorough investigation of the evolution of the PL band as a function of the temperature in order to elucidate luminescence properties using temperature-dependent photoluminescence (PL) measurement. An electrochemical approach was used to create the porous structures. Two well-known PL emission peaks were identified at 663 nm and 818 nm; the broad emission peak at 663 nm was attributed to surface states in porous materials. Based on the intensity evolution with measurement temperature, the current work suggests two distinct nonradiative recombination processes. The influence of surface conditions can be attributed to the thermal extinguishing behavior in the low-temperature region between 10 and 60K. Nevertheless, it is possible to attribute nonradiative recombination activities to thermal escape throughout the upper-temperature range, specifically from 60 to 300 K. It is well acknowledged that gaining a comprehensive understanding of the faults is highly advantageous when considering the application of porous silicon layers in optoelectronic or other devices. [ABSTRACT FROM AUTHOR]

The effect of hydrofluoric (HF) acid concentration on the optoelectronic properties of porous silicon (PS) was investigated. The laser-assisted etching (LAE) method was used to prepare the PS samples. Etching parameters such as an etching period of 12 min and a current density of 20 mA cm−2 were relied upon. The crystallite size of the PS was investigated by XRD as well to provide an estimate of the degree of crystallinity of the etched samples. The XRD pattern exhibits significant (111) peaks at 28.4°. The FESEM investigation shows the roughness and hillocks on the entire surface which can be considered as a point to form small skeleton clusters that play an important role in the strong visible photoluminescence (PL). We can infer from our PL study that the PL peaks regarding the PS samples are related to S-band luminescence, corresponding to the blue–red emission 580–620 nm. A slight PL band position shifts toward shorter wavelengths, which could be explained by reductions in luminescent nanocrystal sizes with a porosity increase. Raman peak shifts and becomes asymmetrically broadened as the dimensions of c-Si are shrunk, as the HF concentration is increased, the Raman sharp peaks become more asymmetrical, and their peak locations shift to lower wavenumber in comparison with our reference bulk data. The analysis is performed on the electrical features of I–V characteristics, barrier height, and PS responsivity. The photosensitivity investigations reveal that responsivity is higher for PS sample prepared at 22% HF concentration. The resultant's PS showed the best stability of the photocurrent, indicating that a high concentration can improve the stability of porous silicon optoelectrical characteristics. Under various HF concentrations, the quantum efficiency is assessed. The obtained results demonstrated rather unique results for the most efficient photodetector performance. [ABSTRACT FROM AUTHOR]

In this study, we used the pulsed laser ablation (PLA) method to make Au:MgO nanoparticles on porous silicon (PS) substrates. The optical characteristics, crystallinity and surface morphology of generated Au:MgO nanoparticles have been investigated with utilizing XRD, TEM, AFM, UV–Vis, PL and fabrication of gas sensors examined at various laser energies. Au:MgO nanoparticles have been manufactured by pulsed laser ablation method (Q-switched) fundamental 1064-nm Nd:YAG, at different laser energies 600, 800 and 1000 mJ and 100 shots, and then sedimentation on surface of PS (porous silicon) layer prepared by photoelectrochemical etching method. The properties of samples are analyzed by XRD (X-ray diffraction), AFM (atomic force microscope) and TEM (transmission electron microscope). The prepared samples were spherical nanoparticles with an average of roughness and diameter 13.4 and 36.76 nm. The production of approximately spherical core- shell of Au:MgO NPs is indicated by TEM with a mean particle size of 10–55 nm. Also the face cubic-centered shape of Au:MgO NPs is revealed by XRD. Eventually, the diversity of running temperature on the sensor sensitivity, recovery times and the time of response for NO2 and H2S gas sensors fabricated from prepared specimens was studied. The maximal sensitivity of Au:MgO NPs/PS excised by laser energy of 800 mJ of NO2 gas was evaluated as 41.1%, while the maximal sensitivity of Au:MgO NPs/PS excised with a pulsed laser of 1000 mJ of H2S gas is much greater compared to NO2 gas. [ABSTRACT FROM AUTHOR]

Due to their significant physical and chemical characteristics, metallic nanoparticles (NPs) have extensive applications. There has been a lot of interest in NPs generation utilizing green synthesis, and x-ray diffraction (XRD) confirmed that green synthesized CdO NPs had a single-phase cubic structure. The average crystallite measure of nanoparticles was 38 nm. Nanoparticles with an unanticipated disk-like shape that agglomerated more in the scenario of green synthesis were observed in (SEM) photos. [ABSTRACT FROM AUTHOR]

The exceptional photoelectromagnetic characteristics of rare-earth elements contribute significantly to their indispensable position in the high-tech industry. The exponential expansion of the demand for high-purity rare earth and related compounds can be attributed to the swift advancement of contemporary technology. Nevertheless, rare-earth elements are finite and limited resources, and their excessive mining unavoidably results in resource depletion and environmental degradation. Hence, it is crucial to establish a highly effective approach for the extraction and reclamation of rare-earth elements. Adsorption is regarded as a promising technique for the recovery of rare-earth elements owing to its simplicity, environmentally friendly nature, and cost-effectiveness. The efficacy of adsorption is contingent upon the performance characteristics of the adsorbent material. Presently, there is a prevalent utilization of porous adsorbent materials with substantial specific surface areas and plentiful surface functional groups in the realm of selectively separating and recovering rare-earth elements. This paper presents a thorough examination of porous inorganic carbon materials, porous inorganic silicon materials, porous organic polymers, and metal–organic framework materials. The adsorption performance and processes for rare-earth elements are the focal points of discussion about these materials. Furthermore, this work investigates the potential applications of porous materials in the domain of the adsorption of rare-earth elements. [ABSTRACT FROM AUTHOR]

The growth of magnesium silicide on porous silicon under high vacuum conditions (10–5–10‒6 Torr) without the chemical removal of silicon oxide and in a limited temperature range of preliminary annealing (Ta = 450°C) is tested for the first time. It is found that the minimum substrate temperature at which deposited magnesium begins to destroy silicon oxide and interact with silicon by forming magnesium silicide (Mg2Si) is 290°C. In the solid phase reaction of magnesium with porous silicon, the optimum temperature at which, after the destruction of silicon oxide, the formation of a continuous Mg2Si film begins is 350°C. It is shown that, at an annealing temperature Ta = 420°C, only a Mg2Si island film of good crystalline quality is formed. The formation of magnesium silicide in all cases is confirmed by X-ray diffraction, scanning electron microscopy, Raman spectroscopy, or Raman micromapping. It is established that the reflection spectrum of the Mg2Si/PS/Si system corresponds to the reflection from porous silicon with a partial increase at 500–900 nm due to the contribution to reflection from magnesium silicide, which increases with increasing film thickness. It is proved that after the heat treatment of porous silicon and the growth of magnesium silicide with a thickness of up to 90 nm, PS photoluminescence is retained, the radiation of which is recorded with partial attenuation in the Mg2Si film without changing the spectral composition, both immediately after growth and after long-term storage under atmospheric conditions (up to 8 months). [ABSTRACT FROM AUTHOR]

In this work, the capacity of porous silicon (PS) machined by laser photoetching was studied as an ethanol sensor, as well as the influences of the type and the conductivity of the crystalline silicon used to obtain sensors. The resistivities used were 1–10 and 0.0014–0.004 Ω∙cm, both wafers were n-type. The response of the device was determined at room temperature (27 °C). The results can be used to appropriately select the conductivity of semiconductor materials to be used as sensors. Infrared spectroscopy confirms the absorption of ethanol in the surface of the photoetched PS. Morphological analysis revealed a macroporous structure, with pore diameters of 2.6 and 0.39 μm for the wafers of 1–10 and 0.0014–0.004 Ω∙cm respectively. The macroporous structure demonstrates a high sensibility and exhibited excellent sensing characteristics during the detection of low concentrations of ethanol. The quantity of ethanol was registered with the changes in the voltage of operation. The performance of the sensor was characterized by curves of voltage vs. time. The minimum quantity of ethanol analyzed was 1 µl. The results demonstrate that photoetched PS has the potential to develop sensitive sensors. [ABSTRACT FROM AUTHOR]

Silicon (Si) is a promising anode material for next-generation lithium-ion batteries (LIBs) with its high theoretical specific capacity (4200 mAh/g). However, Si anode has a huge volume change rate (> 300%) and high cost compared to graphite, which limits the commercial application of Si anode. Carbon coating can effectively tackle the volume change and poor conductivity during cycling of Si anode. In this work, aluminum–silicon alloy was firstly etched by hydrochloric acid. Followed by a mixture with pyrolysis of phenolic resin, the carbon layer outside the silicon particles was deposited during heat treatment process. The carbon-coated porous silicon-carbon (Si/C) anode material demonstrates excellent electrochemical performance and porous structure, which relieves mechanical stress and inhibits volume expansion. The results show that Si/C present well electrochemical performance at a sintering temperature of 800 ℃. Specially, the Si/C anode delivers a high specific capacity of 1394.4 mAh/g at the current density of 0.5 A/g with 46.1% retention. Nitrogen-doped silicon carbon composite material (Si/NC) was synthesized to further improve the performance of Si/C anodes. The characterizations confirm good crystallinity, uniform carbon coating on silicon surfaces, and even distribution of Si, C, and N elements. Simultaneously, a highly stable reversible capacity of 1218.3 mAh/g with 42.7% retention over 300 cycles at a current density of 0.5 A/g was obtained. This research can provide an alternative approach for high-energy and low-cost silicon-based anodes for LIBs. [ABSTRACT FROM AUTHOR]

Modifying photo-anode structures in DSSC devices is still challenging in improving efficiency. This study focused on the ZnO rod growth on several porous silicon substrates using the hydrothermal method and determining which porous silicon is appropriate for DSSC applications. The materials used for the growth solution were Zn(NO3)26H2O 0.05 M and C6H12N4 0.25 M. The hydrothermal process was carried out at 90°C for 6 h and then annealed at 450°C for 30 min. SEM revealed that PSi pore influences the structure, diameter, and density of ZnO rods. ZnO structures formed in ZnO rods with a dominant vertical growth direction, ZnO rods with an intersection direction, and flower-like ZnO rods. The diameter of the PSi pore affected the density of ZnO rods grown on the PSi. The average diameter size and the density of ZnO rods vary from 747.66 -1610.68 nm and 0.22 -0.90 rod/μm². XRD confirmed the presence of ZnO hexagonal wurtzite, Si cubic, and SiO2 monoclinic. UV-Vis spectrometry characterization results showed that sample reflectance was influenced by ZnO rod density and PSi pitch. The larger density of ZnO rods and the smaller pitch of the PSi pore will lead to lower reflectance. In addition, band gap values were obtained in the 3.06 -3.75 eV range. FTIR identified the existence of a ZnO vibration bond, indicating that ZnO was successfully grown on all PSi substrates. The ZnO rods grown on P15 S1180 are expected to have more appropriate properties among all five samples for DSSC photoanode. [ABSTRACT FROM AUTHOR]

The long-time stability of the enhanced porous silicon (PS) optoelectronic properties using samarium (Sm) pore-filling were investigated based on experimental results. Non treated natural and thermally oxidized PS samples were taken as reference. The morphology evolution of the samples was observed by using a scanning electron microscope (SEM). Fourier-Transform Infrared spectra (FTIR) of Sm treated PS (Sm-PS) show the appearance of new band localized at 470 cm−1 and attributed to Sm–O-Si which is persistent after 7 months of air exposure. Photoluminescence (PL) characterization demonstrated a stable threefold increase in the PL intensity of the Sm-PS. However, a blue shift from 1.829 eV to 1.835 eV and 1.890 eV for both natural aged and the thermal annealed PS samples accompanied with a dwindling in the intensity are observed and attributed to the decrease in the silicon crystallite size. The deconvolution of Raman spectrum of Sm-PS sample shows the existence of three bonds localized at 520, 518 and 506 cm−1 and attributed to the crystalline Si substrate, the formation of silicon nanocrystallites (SiNCs) and the compressive strained PS layer after the deposition of Sm layer, respectively. The electrical properties were analyzed based on the effective minority carrier lifetime (τeff) and surface recombination velocity (Seff). The Sm treated samples show the highest τeff about 52 µs and as a result the lowest Seff comparing to the freshly prepared PS which exhibits a τeff of about 13.2 µs due to the passivating capability of Sm layer. These results highlight the effectiveness of coating PS with Sm layer suitable for light emission and photovoltaic applications. [ABSTRACT FROM AUTHOR]

Super hydrophobic porous silicon surface is prepared using a wet chemical synthesis route. Scanning electron microscopic investigation confirms a correlation between pore size and reaction time. SERS substrates are prepared by silver nanoparticle deposition on porous silicon surface. They exhibit excellent characteristics in terms of sensitivity, reproducibility, stability, and uniformity. They could detect rhodamine 6G in femtomolar range with SERS enhancement factor of ~ 6.1 × 1012, which is best ever reported for these substrates. Molecule-specific sensing of water pollutants such as methylene blue, glyphosate, and chlorpyrifos, is demonstrated for concentrations well below their permissible limits along with excellent enhancement factors. Porous silicon substrate functionalized with Ag nanoparticles demonstrates to be a promising candidate for low-cost, long-life, reliable sensors for environmental conservation applications. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal CrystEngComm, which focuses on the design and understanding of solid-state and crystalline materials. It includes a list of papers featured in the issue, covering topics such as photocatalytic hydrogen generation, thermal performance of glass coatings, and Zn ion storage performance. The journal is published by The Royal Society of Chemistry, a leading chemistry community. The document also mentions approved training courses offered by the society. [Extracted from the article]

Recently, silicon has been considered one of the preferred materials for the anodes of next-generation high-energy-density Li-ion batteries due to its advantages of high specific capacity, low working voltage, and abundant reserves. However, the huge volume change and poor electrical conductivity of silicon anodes during the lithiation and de-lithiation process seriously affect their practical application. Herein, honeycomb porous silicon is synthesized by a modified Stöber method and magnesium thermal reduction, which avoids using toxic gases (such as silane) in the traditional preparation of commercial nano-silicon. Moreover, the honeycomb porous structure can effectively alleviate the volume expansion during the charge/discharge process and agglomeration behavior of nano-silicon. Therefore, thanks to its unique structural merits, the honeycomb porous silicon anode is endowed with a reversible specific capacity of 824.1 mA h g−1 after 100 cycles at 0.5 A g−1 and 679.2 mA h g−1 even at an ultrahigh current density of 1.0 A g−1 after an extended cycling period of 200 cycles, which is almost twice that of commercial nano-silicon. More importantly, this finding offers promising advancements in designing silicon anodes in energy storage. [ABSTRACT FROM AUTHOR]