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Porous Silicon Nanoparticles
Published in Sourav Bhattacharjee, Principles of Nanomedicine, 2019
Porous silicon (PSi) has emerged as an exciting material for a multitude of applications, including optoelectronics [1–4], sensing [5, 6], biomedical devices [7], and drug delivery [8, 9]. Its inherent advantages include affordability (silicon is the second-most abundant element in the earth’s crust [10]), biodegradability [11], and biocompatibility [12]. The biodegradability of PSi was first reported by Canham in the 1990s while investigating the photoluminescence of the material [13–16]. However, PSi was first reported by Uhlir in 1956 [17], followed by further investigations conducted by Turner [18], Archer [19], and Watanabe [20]. Later, a seminal work by Canham (1995) revealed the behavior of PSi in simulated body fluids to show that depending on the size of the pores and porosity, PSi can be both bioactive and bioinert [14]. It is known that silicon is enzymatically metabolized inside the body to produce orthosilicic acid—Si(OH)4—which is afterwards excreted in urine [21]. Moreover, the chemistry of silicon as a semiconducting material is well known, with plenty of opportunities for surface conjugation and engineering in order to develop sustained-release formulations. Today, PSi is used to encapsulate various drugs and release them in a controlled fashion. Popular examples of such encapsulable drugs within PSi matrices are anticancer drugs (e.g., cisplatin [22] and doxorubicin [23]), steroids (e.g., dexamethasone [24]), and nonsteroidal anti-inflammatory drugs (NSAIDs, e.g., ibuprofen [25]).
Exploration for Porous Architecture in Electrode Materials for Enhancing Energy and Power Storage Capacity for Application in Electro-chemical Energy Storage
Published in Ranjusha Rajagopalan, Avinash Balakrishnan, Innovations in Engineered Porous Materials for Energy Generation and Storage Applications, 2018
Hierarchically porous silicon nanospheres (hp-SiNSs) when employed in the anode of Li-ion battery shows reversible specifiic capacity of 1850 mAhg–1 at 0.1C (1C = 3.6 Ag–1). Therefore, it is apparent that most of the silicon in the electrode is active due to accessibility by Li+ ions. Following first two cycles at C/20, a capacity exceeding 1800 mAhg–1 could be maintained even after 200 cycles. The Coulombic efficiency for this morphology is 52 per cent at the fiirst cycle but it increases to above 99 per cent after twentieth cycle. In the first few cycles, a stable SEI is formed and the Coulombic effiiciency increases to above 99 per cent. When compared to commercial Si nanoparticles under similar conditions, there is faster decay of capacity in the first 100 cycles from 2000 mAhg–1 to < 1000 mAhg–1. The enhanced cyclability of the hp-SiNSs may be attributed to its unique porous morphology. The discharge capacities are 1850, 1430, 1125, 920 and 700 mAhg–1 respectively at the rates of C/10, C/5, C/2, C and 2C. The cyclability was improved to 600 cycles at a rate of C/2 when the loading decreases from 1 to 0.5 mAhcm–2 (Xiao et al. 2015). The electrodes made of hp-SiNSs achieve a moderate improvement in volumetric capacity of ~ 760 mAhcm–3 compared to ~620 mAhcm–3 observed in graphitic anodes (Magasinski et al. 2010). Thus, morphology of hp-SiNSs holds a significant promise as anode material in Li-ion battery.
SOI Materials and Devices
Published in Robert Doering, Yoshio Nishi, Handbook of Semiconductor Manufacturing Technology, 2017
Sorin Cristoloveanu, George K. Celler
In Section 4.2.2.3, we have already indicated that porous Si is the key to the ELTRAN process. Porous silicon is formed when Si is anodized in an HF solution, an electrochemical process that was first described in detail by Uhlir in 1956 [56]. In the electrolytic cell, a random network of nano-pores is etched out in Si. Baumgart et al. were the first to show that porous Si surface is still an acceptable template for epitaxial Si deposition [57]. Yonehara et al. demonstrated that it is possible and practical to grow device quality single crystalline Si films on the top of porous Si layers [58]. They utilized high temperature annealing in hydrogen, which greatly increases the mobility of Si atoms, to seal the pores at the surface, thus improving the quality of the substrate for the subsequent Si growth. After Si epitaxy and oxidation to form what will become the buried oxide, the donor wafer is bonded to a Si handle wafer. To complete layer transfer, the wafer stack is fractured mechanically along the porous Si layer that is mechanically weak. A fine water jet, aligned with the wafer plane and incident at the perimeter of the wafer pair that is rotated in front of it, breaks the wafers apart.
Green synthesized silver nanoparticles decorated on nanostructured porous silicon as an efficient platform for the removal of organic dye methylene blue
Published in Green Chemistry Letters and Reviews, 2022
Nelson Naveas, Miguel Manso-Silván, Erico Carmona, Karla Garrido, Jacobo Hernández-Montelongo, Gonzalo Recio-Sánchez
In this regard, the employment of appropriate substrates that host AgNPs can solve the problem of recovery of AgNPs to be utilized for several cycles and avoid the risk of bioaccumulation [13]. Different materials have been proposed for this goal including mesoporous materials such as zeolites or polymeric microspheres or others such as graphene [14–16]. In this context, nanostructured porous silicon (nPSi), which consists in a mesoporous structure of silicon nanocrystal, has been used as an efficient host material to incorporate metal nanoparticles and to obtain hybrid semiconductor–metal material [17].
Carbon nanotubes: a review on green synthesis, growth mechanism and application as a membrane filter for fluoride remediation
Published in Green Chemistry Letters and Reviews, 2021
Bayisa Meka Chufa, H. C. Ananda Murthy, Bedasa Abdisa Gonfa, Teketel Yohannes Anshebo
The application of transition metal, iron as a catalyst in the CVD technique resulted in large-scale aligned nanotube production. A mixture of 10% acetylene in nitrogen at a flow rate of 100 cm3/min along with a substrate containing iron nanoparticles rooted in mesoporous silica was placed in the reaction chamber. CNTs were formed on the substrate containing iron nanoparticles catalyst by the deposition of carbon atoms obtained from decomposition of acetylene at 850°C. About 40 shells of multiwalled nanotubes arrays with an outer diameter of 30 nm were formed with a consistent spacing of 100 nm between the pores on the substrate. The SEM result showed the formation of a thin film of nanotube that grew continuously from the bottom to the top with a film length of 50 and 100 mm. The CVD techniques were used to grow consistent arrays of MWCNTs on a perforated silicon wafer substrate. The electrochemical etching of a highly doped n-type Si wafer was used to obtain the porous silicon substrate. The substrate was decorated by Fe films by electron beam evaporation through shallow covered with squared openings having fixed side length and pitch distance. The nanotube with a diameter of 16 nm was formed on the top of the iron catalyst. The CVD process was performed in a tube reactor in the temperature range of 850°C–1000°C from the precursor ethylene under argon atmosphere. This CVD technique was also applied to produce high-quality SWCNTs on a silicon wafer substrate in the presence of transition metal catalyst under noble gas atmosphere. The most commonly used catalyst is Fe/Mo transition metal catalyst on alumina silica composite materials. The characterization of the sample with TEM revealed that a bundle and individual SWCNTs were obtained. The SEM image of the sample also showed that the high quality with a diameter distribution in the range between 0.7 and 5 nm with a peak at 1.7 nm. The increased metal support was the indicator of the large-scale (25) production of the nanotube but the weaker the metal support the larger the agglomeration formation. The section of procedural activity and the schematic diagram of CVD experimental setup for the synthesis of CNT were shown in Figure 5.
Dealloying of modified Al-Si alloy to prepare porous silicon as Lithium-ion battery anode material
Published in International Journal of Green Energy, 2022
Rongfu Xu, Yueya Shi, Wenhao Wang, Yong Xu, Zhigang Wang
Compared with silicon anode, this volume change of graphite anode is a trivial problem during the lithiation process, which is a mixture of graphite and carbon black with a nearly 30% void space accommodated for the volume change of graphite during lithiation. Therefore, to overcome these problems and achieve stable anode materials, scholars have carried out numerous research, such as Si of different nanostructures (Chan et al. 2010; Igor et al. 2011; Jung-Keun et al. 2012; Ma et al. 2007; Park et al. 2009), metal silicates (Wang et al. 2021a, 2021c), silicon matrix composites (Feng et al. 2012; Wang et al. 2021b; Wu et al. 2012), porous Si (Feng et al. 2015; Jia et al. 2011; Jiang et al. 2014), which have been proposed and achieved significant results. Among these strategies, porous Si is considered to be a more effective way for battery performance. Because the porous structure has more free space can effectively adapt to volume expansion and alleviate mechanical stress. There are many processes for preparing porous silicon, such as electrochemical corrosion (Yurong 2010), metal-assisted chemical etching (Huang et al. 2011; Jin et al. 2015), chemical corrosion, magnesiothermic reduction (Gao et al. 2017; Wang et al. 2016; Xu 2020), and dealloying (Jiang et al. 2014; He et al. 2015; Yang et al. 2018). In the past few years, the Al-Si alloy de-alloying process has been widely used for the fabrication of porous silicon. The preparation process was first proposed by Jiang et al. (2014), who prepared porous silicon powders by acid etching Al-20%Si alloy powder using HCl. Anil D. Pathak et al. (2019) ball-milled Al-50%Si powder to obtain alloy micro powder (~100 μm) and prepared porous silicon materials by etching the alloy powder using 3.0% KOH solution. Hao, Li, and Zhu (2014) prepared porous silicon materials by using acid etching of Al-20%Si alloy powder. All studies mentioned above, Al-Si alloy powders are often used as raw materials to obtain porous silicon powders, but the cost of the alloy powder is high. Casting Al-Si alloy is a more economical and simpler raw material for preparing porous silicon than Al-Si alloy powder. The presence of large size eutectic silicon and primary silicon in the microstructure of hypereutectic Al-Si alloy makes it necessary to refine the silicon phase of cast Al-Si alloy ingots before acid etching.