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Two-dimensional silicon (Si) nanosheets are becoming increasingly exciting for photocatalytic applications. Their unique morphology and physiochemical properties make it attractive in heterojunction engineering. In this work, we report the construction of 2D H–Si/g-C3N4 hybrid as a heterojunction photocatalyst for solar photocatalytic hydrogen evolution. The exfoliated silicon nanosheets etched by hydrofluoric acid exhibit a hydrogen-terminated surface with an inverse charging state, which can thus be easily anchored onto g-C3N4 nanosheets by self-assembly. The optimized H–Si/g-C3N4 heterojunction photocatalyst with Pt as the cocatalyst achieved an improved photocatalytic hydrogen production rate which is about 2 times that of g-C3N4 nanosheets under simulated sunlight irradiation using methanol as the sacrificial agent. Density functional theory calculations revealed that the built-in electric field (BIEF) at the H–Si/g-C3N4 interface contributes to the spatial charge separation of the heterojunction. The BIEF leads to an S-scheme carrier transfer mechanism at the H–Si/g-C3N4 interface that benefits the carrier separation on g-C3N4 nanosheets, resulting in uniform deposition of the Pt cocatalyst at the heterojunction interface and improved photocatalytic performance. This work not only expands the application of silicon nanosheets by supporting the potential of 2D H–Si/g-C3N4 heterojunction in photocatalytic reactions but also provides valuable insights to the interface behavior of the H–Si/g-C3N4 heterostructure. [ABSTRACT FROM AUTHOR]

Layered silicon nanosheets (SiNSs) have attracted considerable attention owing to their unique combination of chemical and physical properties, which makes them an exciting candidate for next-generation on-chip light sources and lasers. Despite over 150 years of research on SiNSs, the effects of the CaSi2 precursor quality on SiNSs have not been studied. Here, we report a comparison of CaSi2 (and SiNSs derived therefrom) synthesized from two reaction pathways: (1) melting Ca and Si (elemental melting, or EM-CaSi2) and (2) the less-explored reaction between CaH2 and Si (hydride synthesis, or HS-CaSi2). We demonstrate that both reaction pathways lead to CaSi2, but the HS-CaSi2 pathway requires only a single step without the need to melt the CaSi2 product and at a temperature below the peritectic decomposition of CaSi2. We find that the EM-CaSi2 exhibits grains that lay flat against the substrate, whereas the HS-CaSi2 has little preferred orientation. We deintercalated both EM- and HS-CaSi2 with HCl at −35 °C to yield hydrogen-terminated SiNSs. We characterized the SiNSs and found that the HS-SiNSs and EM-SiNSs exhibit properties that are nearly identical, with the exception that the morphology of the precursor is imparted to the SiNSs. These results provide the community with a one-step method to synthesize CaSi2 and demonstrate that the morphology of CaSi2 and SiNSs can be controlled with different synthetic techniques. [ABSTRACT FROM AUTHOR]

The silicon nanosheet/carbon composite emerges as a promising anode material for the next-generation commercial lithium-ion batteries. However, complex, costly, and energy-intensive synthesis procedures impede its practical application. Herein, the carbon-coated silicon nanosheets (Si/C) have been successfully synthesized via a one-pot strategy, involving a modified magnesiothermic reduction of talc followed by a reaction with CO 2. The distinct chemical composition and layered nanostructure of talc enable the retention of Si nanosheets during exothermic reactions without additional templates or heat absorbents. The method shows significant potential for the scalable production of Si/C owing to the abundant silicon source, sustainable carbon source, and straightforward protocol. The resulting Si/C displays a hierarchical porous structure, with both macropores and mesopores, and an interconnected network of carbon-coated Si nanosheets. These structural characteristics facilitate rapid Li+ diffusion and enable the material to accommodate the lithiation-induced mechanical strains. As a result, the Si/C electrode exhibits outstanding electrochemical performance, including a remarkable rate capability (with a specific capacity of 1220 mAh g−1 at 10.0 A g−1) and a high initial Coulombic efficiency of 88%. The work opens a new avenue for the development of Si/C composites from natural clay minerals through an economical and scalable strategy, which would contribute to the practical application of advanced Si-based anodes in lithium-ion batteries. [Display omitted] • Carbon-coated silicon nanosheets (Si/C) was successfully synthesized from talc by a one-pot method. • Unique chemical composition and layered structure of talc enable the retention of Si nanosheets. • Si/C showed hierarchical porous structure consisting of carbon-coated Si nanosheets. • Si/C as anodes in lithium-ion battery exhibited superior electrochemical performance. [ABSTRACT FROM AUTHOR]

Si nanosheets (SiNS) as two dimensional Si nanomaterials are promising candidates for anodes of lithium ion batteries (LIBs) by their large surface area and excellent mechanical durability. In this study, we fabricated polymeric binder (carboxymethyl cellulose, CMC) coated SiNS electrodes using a spin-coating process and characterized the electrochemical properties. The CMS coated SiNS electrodes were homogeneously covered with a CMC polymer layer and showed the improved capacity retention with maintaining over 90% of initial capacity after several cycles. The result of electrochemical impedance spectroscopy indicates that the CMC layer provide the chemical stability of Si surface and suppress the continuous growth of the SEI layer. Furthermore, CMC coated layer on SiNS provide improved mechanical stability that maintains the adhesion of SiNS to the current collector during the discharge–charge cycles. [ABSTRACT FROM AUTHOR]

Si nanosheets (NSs) are synthesized by the arc-discharge plasma and successfully anchored onto the surface of porous carbon (PC) substrate via physical adhesion assisted with ultrasonic blending. The PC matrix is obtained by high-temperature calcination of the mixture of glucose and calcium carbonate, followed by acid washing for removal of the oxidization products. The contents of Si NSs loaded are fixed at Si/PC = 1:9, 3:7, and 5:5 (in mass), respectively. It is found that the anode with the optimum composition of 30 wt% Si NSs exhibits the best electrochemical performances, owing to a homogeneous dispersion of Si NSs on the PC substrate without severe aggregation, typically a stable discharge specific capacity of 1252 mAh·g−1 with the coulombic efficiency of 99.58% at the current density of 100 mA·g−1 after 100 cycles while retains the capacity of 850 mAh·g−1 even at a high current density of 1 A·g−1 after 800 cycles. In comparison with the entire Si NSs electrode, the best Si/PC composite anode shows two times higher in the capacity retention ability and the excellent rate performance, due to the electrical contribution and large specific surface/pore volume of the PC matrix, which also plays positive roles in mass infiltration of electrolyte and rapid transport/diffusion of electrons/Li+ ions inside the electrodes. [ABSTRACT FROM AUTHOR]

The present work reports on the transient nonlinear optical (NLO) responses of two different types of 2D silicon nanosheets (SiNSs), namely hydride-terminated silicon nanosheets (SiNS–H) and 1-dodecene-functionalized silicon nanosheets (SiNS–dodecene). The main motivation of this study was to extend the knowledge regarding the NLO properties of these Si–based materials, for which very few published studies exist so far. For that purpose, the NLO responses of SiNS–H and SiNS–dodecene were investigated experimentally in the nanosecond regime at 532 and 1064 nm using the Z-scan technique, while the obtained results were compared to those of certain recently studied graphene nanosheets. SiNS–dodecene was found to exhibit the largest third-order susceptibility χ(3) values at both excitation wavelengths, most probably ascribed to the presence of point defects, indicating the importance of chemical functionalization for the efficient enhancement and tailoring of the NLO properties of these emerging 2D Si-based materials. Most importantly, the results demonstrated that the present silicon nanosheets revealed comparable and even larger NLO responses than graphene nanosheets. Undoubtedly, SiNSs could be strong competitors of graphene for applications in 2D-material-based photonics and optoelectronics.

Highlights • New properties are introduced for novel 2D materials based sensor technology. • Oxidation of 2D silicon leads to highly porous and sensitive material. • The subsequent functionalization leads to precise engineering of the surface. • Cheap and reproducible way was found to access sensitive sensor system fabrication. Abstract The use of completely oxidized two-dimensional (2D) silicon nanosheets (SiNSs) represents a novel approach for the application of 2D silicon-based materials in the nanoelectronics field. Densely stacked and highly porous oxidized SiNSs (OSiNSs) act as a sensitive layer for humidity detection. Due to the oxidation-caused porosity of the SiNSs and the possibility functionalize the 2D surface with hydrophilic groups, this hybrid material exhibits an extremely good sensitivity towards relative humidity (RH). In this work, precise tuning of the SiNSs' sensing properties by their functionalization is demonstrated. In particular, the modification with methacrylic acid (MAA) groups, leading to SiNS-MAA, and the subsequent deposition on interdigitated electrodes double the capacitance value in the range of 20–85%RH. These values were achieved after the full oxidation of SiNS-MAA in ambient conditions. The mentioned changes in capacitance are extremely high compared to the response of the so far known common polymer humidity sensors. Contrary to that, this response is neutralized when the SiNSs are functionalized with tert -butyl acrylic acid (tBMA), a rather hydrophobic functional group. The fabricated devices show, how the specific functionalization of SiNSs serves as a reliable tool to provide sensitivity towards RH. Similar approach, based on tuning the functionality, can be applied to achieve e.g., sensor array selectivity. For this purpose, the functional groups on the surface of the nanomaterial can be further modified. Additional molecules with sensitivities towards various surrounding conditions could be attached. Furthermore, these functional molecules can be used for subsequent (bio)molecule immobilization, which can serve as sensitive molecular groups towards surrounding substrates and gases. However, one of the main challenges in sensor technology is to find a highly selective solution: a sensor system capable to differentiate among different vapor species. The described strategy can serve as an access towards new and promising solutions, which can help to face this issue in modern nanomaterials-based technology. [ABSTRACT FROM AUTHOR]

Abstract: Low-dimensional silicon (Si) nanostructures have been attracting a significant attention for various applications including electrical, optical, energy devices, and bio-chemical sensors. Two-dimensional Si nanostructures, i.e., Si nanosheets (SiNSs), are promising owing to their extremely large surface area, mechanical flexibility, and band gap modulation. In order to exploit the potentials of SiNSs, the doping of these nanostructures is crucial; however, this has not been yet extensively investigated. In this paper, we report an n-type phosphorus doping of SiNSs using a spin-on dopant proximity technique that was employed to deposit a thin film of phosphosilicate glass by evaporation. Structural and X-ray measurements results reveal that the phosphorus atoms are substitutionally doped and that the crystallinity and structure of the SiNSs are preserved after the doping. Electrical measurements show that the SiNSs are heavily n-type doped. The doping level can be modulated by adjusting the annealing temperature.Graphical Abstract: [ABSTRACT FROM AUTHOR]

Silicon/carbon composites are considered as the preferred anode materials for high energy density lithium-ion batteries due to their high capacity. However, the high cost of raw materials and the complex preparation process have resulted in expensive cost and poor batch stability of silicon-carbon materials, which have impeded their widespread adoption on a large scale. In this study, a multistage stable silicon-graphite nanosheets composite (Si-NSs/G-NSs@C) with intercalated and core-shell structure was produced from low-cost precursors of silicon nanosheets (Si-NSs) and graphite nanosheets (G-NSs) by simple modification-grafting-coating and heat treatment processes. Benefiting from the effective bonding, citric acid carbon coating, intercalation and core-shell structure, the Si-NSs/G-NSs@C composite exhibits excellent performance for lithium storage. The Si-NSs/G-NSs@C electrode, using the sodium alginate binder system, displays the reversible specific capacity of 821.4 mAh g −1 at 400 mA g −1, with the capacity retention rate of 80% after 200 cycles. When employing lithium polyacrylate as the binder, the composite electrode demonstrates the reversible specific capacities of 1048.9 mAh g −1 at 400 mA g −1 and 723.6 mAh g −1 at 1000 mA g −1. After 200 cycles, the capacity retention rates were 81% and 85%, respectively. In summary, the low-cost precursors, simple and controllable preparation process and excellent electrochemical performance will further promote the market application of silicon/carbon anode materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Silicon (Si) is regarded as the promising next-generation commercial anode in high energy lithium-ion batteries (LIBs), attributed to its natural abundance, high theoretical capacity (4200 mAh g−1) and low voltage profile (<0.5 V). However, the huge volume change and tremendous capacity fading of silicon during lithiation/de-lithiation have been hindering its practical application. Herein, a facile and scalable method was proposed to prepare the Si nanosheets limited in 3D porous N-doped carbon micro cages (Si@NCM) particles with ternary oxygen-bridged covalent chemical bond, i.e. , Si–O–C bonding. As a kind of anode materials, the Si@NCM rendered an extremely surprising reversible capacity of 930.2 mAh g−1 after 2000 cycles at a current density of 5 A g−1 at ambient temperature. More interestingly, it afforded an overwhelming capacity of 950.7 mAh g−1 after 3000 cycles at 20 A g−1 at 80 °C, with 89.8% capacity retention, and an excellent rate capability of 594.8 mAh g−1 at 50 A g−1. The impressive electrochemical performance was ascribed to its multi-scaled network structure and moderate covalent bonding, which enhanced Li+ diffusion kinetics and accommodated the volume expansion of the silicon. This simple fabrication approach holds great commercial possibility in practical application of next-generation advanced LIBs. • 3D porous Si@C electrodes are prepared by a facial and scalable spray-drying process. • The N-doped carbon shell is propitious to the caption and transportation of Li+. • Formation of Si–O–C and mesopores contributed to the stable operation of Si@NCM. • 3D Si@NCM electrodes exhibited 930.2 mAh·g−1 over 2000 cycles at 5 A g−1. [ABSTRACT FROM AUTHOR]

Various Lewis acids are found to efficiently catalyze hydrosilylation reactions of hydride-terminated 2D silicon nanosheets at room temperature. The hydride-terminated nanosheets can be functionalized with a variety of unsaturated functional substrates and still possess their unique characteristic (opto)electronic properties (e.g., photoluminescence). This is demonstrated by successfully implementing the readily functionalized materials into new silicon/semiconducting polymer-based field-effect transistors (FETs). Surface modification of the freestanding silicon nanosheets opens new possibilities to form highly homogeneous blends with the already broadly used conventional polymers poly(3-hexylthiophene-2,5-diyl). The consequential combination of the different properties of the materials enables the enhancement of the sensitivity of the solution-gated FETs and increases the transconductance of the operating device. [ABSTRACT FROM AUTHOR]

We have specified the synthetic conditions to obtain one-directionally ordered CaSi2 microwall arrays vertically grown on a Si substrate. Our basic concept is based on the utilization of the Kirkendall effect for reactive deposition epitaxy (RDE). We found for the first time that: 1) a much larger Ca vapor supply on the Si substrate than the conventional RDE, 2) the adoption of a two-step heating process, and 3) the selection of the crystal axis of the Si surface are the keys to control the microstructures of CaSi2 on the Si substrate. The CaSi phase was first formed on Si, then the CaSi2 phase was formed at the CaSi/Si interface. Based on the Kirkendall effect, the interdiffusion of Ca and Si was enhanced in the vertical direction rather than in the parallel direction to the Si surface. CaSi2 tends to grow along four equivalent Si{111} planes, however, the specific orientation of the Si surface resulted in CaSi2 microwalls grown along its Si(11 [ABSTRACT FROM AUTHOR]

Herein, the synthesis and characterization of the first polymeric nanocomposite based on silicon nanosheets (SiNSs) are reported. In a one-step reaction, the formation of the polymeric matrix material and simultaneous functionalization of the SiNSs with polymers occur via radical polymerization of organic monomers such as styrene, methyl methacrylate, and acrylic acid. Depending on the purification method used, a covalently linked nanocomposite or the functionalized SiNSs are obtained. SiNSs decompose when exposed to basic conditions or to UV light. The UV-light-based decomposition is briefly investigated. In the nanocomposite, the stability of the 2D nanomaterial enhances significantly against these external influences, while the optoelectronic properties (e.g., photoluminescence) of the SiNSs and the processing characteristics of the polymeric matrix are preserved. [ABSTRACT FROM AUTHOR]

Herein we present the functionalization of freestanding silicon nanosheets (SiNSs) by radical-induced hydrosilylation reactions. An efficient hydrosilylation of Si−H terminated SiNSs can be achieved by thermal initiation or the addition of diazonium salts with a variety of alkene or alkyne derivatives. The radical-induced hydrosilylation is applicable for a wide variety of substrates with different functionalities, improving the stability and dispersibility of the functional SiNSs in organic solvents and potentially opening up new fields of application for these hybrid materials. [ABSTRACT FROM AUTHOR]

The two-dimensional (2D) growth of cubic-structured (silicon) Si nanosheets (SiNSs) was investigated. Freestanding, single-crystalline SiNSs with a thickness of 5-20 nm were grown on various Si substrates under an atmospheric chemical vapor deposition process. Systematic investigation indicated that a diffusion-limited aggregation (DLA) environment that leads to dendritic growth in <110> directions at the initial stage is essential for 2D growth. The kinetic aspects under DLA environments that ascribe to the dendritic and 2D growth were discussed. Under the more dilute conditions made by addition of Ar to the flow of H, the SiNSs grew epitaxially on the substrates with periodic arrangement at a specific angle depending on the orientation of the substrate. It reveals that SiNSs always grew two dimensionally with exposing (111) surfaces. That is thermodynamically favorable. [ABSTRACT FROM AUTHOR]

The present work reports on the transient nonlinear optical (NLO) responses of two different types of 2D silicon nanosheets (SiNSs), namely hydride-terminated silicon nanosheets (SiNS–H) and 1-dodecene-functionalized silicon nanosheets (SiNS–dodecene). The main motivation of this study was to extend the knowledge regarding the NLO properties of these Si–based materials, for which very few published studies exist so far. For that purpose, the NLO responses of SiNS–H and SiNS–dodecene were investigated experimentally in the nanosecond regime at 532 and 1064 nm using the Z-scan technique, while the obtained results were compared to those of certain recently studied graphene nanosheets. SiNS–dodecene was found to exhibit the largest third-order susceptibility χ(3) values at both excitation wavelengths, most probably ascribed to the presence of point defects, indicating the importance of chemical functionalization for the efficient enhancement and tailoring of the NLO properties of these emerging 2D Si-based materials. Most importantly, the results demonstrated that the present silicon nanosheets revealed comparable and even larger NLO responses than graphene nanosheets. Undoubtedly, SiNSs could be strong competitors of graphene for applications in 2D-material-based photonics and optoelectronics. [ABSTRACT FROM AUTHOR]

Despite extensive studies for the last several decades, commercialization of silicon based anode materials for high-capacity batteries is slow. In particular, silicon demonstrates the rapid volumetric changes result in drastic capacity degradation for rechargeable lithium-ion batteries (LIBs). Here, we evaluate uniformly carbon-coated Si nanosheets (C-SiNSs) as effective anode materials in LIBs. We utilize the parylene C, an insulation polymer, to make a coating with a uniform thickness on the SiNSs using the chemical vapor deposition (CVD) method at room temperature. The synthesis method of the C-SiNSs includes a simple pyrolysis process at 950 °C after the uniformed parylene C coating on SiNSs. Particularly, the C-SiNSs coated with 10 nm carbon for anode material improve the capacity and the cycle performance (~2100 mAh g−1 for the 300th cycle at 0.15 C-rate) with approximately 100 % coulombic efficiency. [Display omitted] • We prepared uniformly carbon-coated silicon nanosheets using a parylene C as C-SiNSs. • C-SiNSs prepared by a simple method using a CVD coating and pyrolysis. • C-SiNSs as anode materials show enhanced capacity and cycle performance for LiBs. [ABSTRACT FROM AUTHOR]

The present work reports on the transient nonlinear optical (NLO) responses of two different types of 2D silicon nanosheets (SiNSs), namely hydride-terminated silicon nanosheets (SiNS-H) and 1-dodecene-functionalized silicon nanosheets (SiNS-dodecene). The main motivation of this study was to extend the knowledge regarding the NLO properties of these Si-based materials, for which very few published studies exist so far. For that purpose, the NLO responses of SiNS-H and SiNS-dodecene were investigated experimentally in the nanosecond regime at 532 and 1064 nm using the Z-scan technique, while the obtained results were compared to those of certain recently studied graphene nanosheets. SiNS-dodecene was found to exhibit the largest third-order susceptibility χ (3) values at both excitation wavelengths, most probably ascribed to the presence of point defects, indicating the importance of chemical functionalization for the efficient enhancement and tailoring of the NLO properties of these emerging 2D Si-based materials. Most importantly, the results demonstrated that the present silicon nanosheets revealed comparable and even larger NLO responses than graphene nanosheets. Undoubtedly, SiNSs could be strong competitors of graphene for applications in 2D-material-based photonics and optoelectronics.

Atomically thin silicon nanosheets (SiNSs), such as silicane, have potential for next-generation computing paradigms, such as integrated photonics, owing to their efficient photoluminescence emission and complementary-metal-oxide-semiconductor (CMOS) compatibility. To be considered as a viable material for next-generation photonics, the SiNSs must retain their structural and optical properties at operating temperatures. However, the intersheet disorder of SiNSs and their nanoscale structure makes structural characterization difficult. Here, we use synchrotron X-ray diffraction and atomic pair distribution function (PDF) analysis to characterize the anisotropic disorder within SiNSs, demonstrating they exhibit disorder within the intersheet spacing, but have little translational or rotational disorder among adjacent SiNSs. Furthermore, we identify changes in their structural, chemical, and optical properties after being heated in an inert atmosphere up to 475 °C. We characterized changes of the annealed SiNSs using synchrotron-based total X-ray scattering, infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, electron paramagnetic resonance, absorbance, photoluminescence, and excited-state lifetime. We find that the silicon framework is robust, with an onset of amorphization at ∼300 °C, which is well above the required operating temperatures of photonic devices. Above ∼300 °C, we demonstrate that the SiNSs begin to coalesce while keeping their translational alignment to yield amorphous silicon nanosheets. In addition, our DFT results provide information on the structure, energetics, band structures, and vibrational properties of 11 distinct oxygen-containing SiNSs. Overall, these results provide critical information for the implementation of atomically thin silicon nanosheets in next-generation CMOS-compatible integrated photonic devices.

Surface-anisotropic nanoparticles represent a new class of materials that shows potential in a variety of applications, including self-assembly, microelectronics, and biology. Here, the first synthesis of surface-anisotropic silicon quantum dots (SiQDs), obtained through masking on 2D silicon nanosheets, is presented. SiQDs are deposited on the 2D substrate, thereby exposing only one side of the QDs, which is functionalized through well-established hydrosilylation procedures. The UV-sensitive masking substrate is removed through UV-irradiation, which simultaneously initiates the hydrosilylation of a second substrate, thereby introducing a second functional group to the other side of the now free-standing SiQDs. This renders surface-anisotropic SiQDs that have two different functional groups on either side of the particle. This method can be used to introduce a variety of functional groups including hydrophilic and hydrophobic substrates, while the unique optoelectronic properties of the SiQDs remain unaffected. The anisotropic morphology of the QDs is confirmed through the aggregation behavior of amphiphilic Janus SiQDs at the interface of water and hexane. Additionally, anisotropic SiQDs are used to produce the first controlled (sub)monolayer of SiQDs on a gold wafer., (© 2021 The Authors. Advanced Materials published by Wiley-VCH GmbH.)

• Thermal plasma is used to prepare Si nanospheres and Si nanosheets simultaneously. • Separation of nanospheres and nanosheets can be simply achieved by sampling at different locations. • Si nanosheets were prepared with bottom-up route under proper growth condition in thermal plasma system. Silicon nanospheres and nanosheets were directly synthesized from micro-silicon under atmospheric pressure using thermal plasma system, and collected from different locations. Average size of nanospheres was around 35 nm, and length/width of nanosheets varied from tens to hundreds nanometers with thickness in tens nanometers. Morphology of prepared nano-Si could be mainly affected by growth conditions after homogeneous nucleation. Continuous production of silicon nanospheres/nanosheets would be achieved by thermal plasma approach. [ABSTRACT FROM AUTHOR]

Silicon nanosheets-polyvinyl alcohol (Si-PVA) film was prepared and employed as a SA in obtaining an erbium-doped Q-switched laser. To the best of our knowledge, this is the first time that few-layer silicon nanosheets has been used as a SA to achieve a Q-switched erbium-doped fiber laser. We have demonstrated passively Q-switched operation with an average output power of 0.89 mW, a peak pulse power of 6.52 mW, and a pulse width of 2.32 μs with a repetition rate of 58.7 KHz. The results indicate that silicene owns excellent nonlinear properties and extensively potential applications in ultrafast photonics. [ABSTRACT FROM AUTHOR]

2D silicon nanosheets (SiNSs) are promising materials for biomedicine but facile synthesis of SiNSs remains a challenge. Herein, by means of a sulfur-iodine co-assisted chemical vapor transport method, octahedron silicon (oct-Si) crystals with fully exposed {111} planes are prepared as precursors for efficient synthesis of SiNSs by facet-selective exfoliation. The 13 nm thick SiNSs have good biocompatibility and the sharp Raman scattering signal facilitates intracellular Raman imaging upon exposure to a near-infrared (NIR) laser. Furthermore, the SiNSs have excellent NIR photothermal characteristics such as a large extinction coefficient of 11.3 L g -1 cm -1 and high photothermal conversion efficiency of 21.4% at 1064 nm. In vitro experiments demonstrate superior NIR-II photothermal therapeutic effects in killing cancer cells. Comparing to conventional methods, the novel facet-selective cleavage strategy is more controllable and environmentally friendly boding well for the fabrication of non-van der Waals 2D materials. The multimodal photonic behavior also suggests large potential of the SiNSs pertaining to integrated multi-NIR biophotonic techniques using single nanomaterials., (© 2020 Wiley-VCH GmbH.)

The increasing problem of bacterial resistance to the currently effective antibiotics has resulted in the need for increasingly potent therapeutics to eradicate pathogenic microorganisms. 2D nanomaterials (2D NMs) have unique physical and chemical properties that make them attractive candidates for biomedical applications. Recently, the application of 2D NMs as antibacterial agents has attracted significant attention. Herein, a novel 2D graphene-like silicon nanosheet (GS NS) antimicrobial agent is fabricated from pristine silicon crystals by ultrasonication, which results in a highly exfoliated planar morphology and a significantly larger surface area as compared with bulk silicon. The GS NSs exhibit remarkable in vitro broad-spectrum bactericidal activity against Gram (-) Escherichia coli and Gram (+) Staphylococcus aureus because of a close interaction with the bacteria, which leads to highly efficient membrane destruction. The in vivo studies demonstrate that the local administration of GS NSs effectively mitigates implant-related infection by reducing the bacterial burden of the extracted samples and accelerating the remission of local inflammation. Based on these encouraging results, GS NSs are expected to be a useful new member of the 2D NMs family, with the potential of effectively killing pathogenic bacteria in clinical applications., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Silicanes are predicted to be a candidate for next‐generation (opto‐)electronics nanomaterials. However, their low carrier or hole densities hinder their practical use in electronic materials. If conjugated substituents (e.g., electron donators or electron acceptors) could be attached to the surfaces of silicanes, these would be effective channel materials for phototransistors and exhibit the corresponding characteristic optoelectronic properties. Herein, the synthesis of silicanes modified by conjugated substituents is reported, and the performances of organo‐modified silicanes/graphene hybrid phototransistors are also evaluated. The room temperature hole mobility of the demonstrated phototransistors is ≈5 cm2 V−1 s−1. In this phototransistor, electron transfer from organo‐modified silicanes to graphene is observed after irradiation with visible light. This approach is applicable to other group IV elemental 2D materials, including germanane and stanane. [ABSTRACT FROM AUTHOR]

In article number 1606764, the modification of twodimensional silicon nanosheets catalyzed by different Lewis acids is described by Jonathan G. C. Veinot, Bernhard Rieger, and co‐workers. A derived functional hybrid film of silicon nanosheet/poly(3‐hexylthiophene) is applied to fabricate field effect transistors with enhanced sensitivity and increased transconductances. The authors thank Johannes Richers for designing the artwork and TUM GS for financial support. [ABSTRACT FROM AUTHOR]

B. Rieger and co‐workers describe on page 6711 the synthesis of silicon nanosheet based composite materials. The two‐dimensional silicon monolayers exhibit outstanding (opto)electronic properties, but were found to be sensitive to UV light. In the synthesized composites they keep their unique characteristics and are protected from external influences. The authors would like to thank Johannes Richers for the design of the artwork and TUM GS for financial support. [ABSTRACT FROM AUTHOR]

We have specified the synthetic conditions to obtain one-directionally ordered CaSi 2 microwall arrays vertically grown on a Si substrate. Our basic concept is based on the utilization of the Kirkendall effect for reactive deposition epitaxy (RDE). We found for the first time that: 1) a much larger Ca vapor supply on the Si substrate than the conventional RDE, 2) the adoption of a two-step heating process, and 3) the selection of the crystal axis of the Si surface are the keys to control the microstructures of CaSi 2 on the Si substrate. The CaSi phase was first formed on Si, then the CaSi 2 phase was formed at the CaSi/Si interface. Based on the Kirkendall effect, the interdiffusion of Ca and Si was enhanced in the vertical direction rather than in the parallel direction to the Si surface. CaSi 2 tends to grow along four equivalent Si{111} planes, however, the specific orientation of the Si surface resulted in CaSi 2 microwalls grown along its Si(111‾ ) plane, the only plane directing nearly vertical to the surface among the Si{111} planes. These results suggest that the Kirkendall effect under asymmetric growth of target materials would be a rational strategy to obtain their ordered microstructures., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)