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Abstract: A pyramid/nanowire binary structure is fabricated on the silicon surface via a NaOH anisotropic etching technique followed by a silver-catalyzed chemical etching process. The silicon surface shows a stable superhydrophobicity with high contact angle of 162° and small sliding angle less than 2° after being modified with octadecyltrichlorosilane (ODTS). The binary roughness of pyramid/nanowire structure presents a stable composite interface of silicon–air–water and responsible for the superhydrophobicity of silicon surface. [Copyright &y& Elsevier]

Abstract: The tribological behaviors and phase transformations of single-crystal silicon against Si3N4 with different sliding velocities and durations under low contact stress at room temperature were investigated. SEM and Raman analysis indicate that phase transformation was involved and characterized by plastically deformed area which consists of Si-III, Si-XII, and a-Si, especially in the early stage at the low sliding velocity. The plastically deformed layer was wiped off at high-velocity or long sliding duration. TEM analysis indicated that the wear debris consists of amorphous silicon. [Copyright &y& Elsevier]

Abstract: Scratch tests on single crystal silicon under dry sliding and pentadecane lubrication are performed on a commercially available nano-scratch tester. Loads range of elastic, elasto-plastic deformation and fracture are classified according to depth-load curves. A fully plastic removal of single crystal silicon below critical load for fracture is observed under pentadecane lubrication, which is quite different from that under dry sliding. Raman micro-spectra indicate that the phase compositions of the scratched track under dry sliding consist of a number of phases, including Si-I, Si-III, Si-XII and a-Si, while the phase composition of the track under pentadecane lubrication consists of single a-Si. Based on the results obtained, a simple approach to fabricate amorphous silicon pattern on single crystal silicon is introduced and discussed. [Copyright &y& Elsevier]

[Display omitted] • Ultra-firm homogeneous COF with ∼7 nm of tetragonal structure layers was prepared on the silicon nanoparticles surface. • The PMDA-NiPc@Si electrode shows only ∼44% of expansion rate, which is only 27.3% of that of the Si electrode. • The reversible capacity of 654 mAh g-1 with retention rate of 80.4% can still be maintained after 2000 cycles at 5 A g-1. • PMDA-NiPc@Si exhibits excellent Li+ conductivity after pre-lithiation, significantly improving initial coulombic efficiency. • The PMDA-NiPc@Si/NCM811 full battery can still preserve 175.8 mAh g-1 and 85.8% capacity retention after 100 cycles at 0.2 C. The enormous volume change of silicon (Si) leads to pulverization of Si electrodes and continuous growth of solid-electrolyte-interphase (SEI) layers on the Si surface, for which we report a new Si anode material (PMDA-NiPc@Si) with a homogeneous and tetragonal covalent organic frameworks (COFs) coating on the surface of nano-Si particles. COFs with tetragonal structures have higher stability than other structures, which helps to increase the long cycle life of the electrodes. The strong constraining buffering effect of the coating layer can fully inhibit and buffer the volume change of Si nanoparticles during charging-discharging, reduce the consumption of electrolytes and form a homogeneous, stable and robust, LiF- and LiN-rich SEI film, and ultimately improve the rate performance and long-cycle performance. The pre-lithiation of PMDA-NiPc@Si shows a superior lithium ion conductivity that can enhance the lithium ion transport kinetics of silicon electrodes and significantly improve the initial coulomb efficiency (ICE). PMDA-NiPc@Si exhibits excellent specific capacity and cycling performance, with a capacity retention rate of 93.8 % after 100 cycles, which is 2.7 times higher than that of nano-Si. It also offers a high reversible capacity of 654 mAh/g and a capacity retention rate of 80.4 % after 2000 cycles at 5 A/g. The assembled full battery with PMDA-NiPc@Si anode and NCM811 cathode displayed a specific capacity of 175.8 mAh/g with a retention rate of 85.8 % after 100 cycles at 0.2C. The PMDA-NiPc@Si electrode shows only about 44 % of the expansion rate (21.6 to 31.1 μm), which is only 27.3 % of that of the Si electrode. PMDA-NiPc@Si anodes show significantly enhanced electrochemical performance, which will provide novel ideas for the development of high-performance Li-ion batteries. [ABSTRACT FROM AUTHOR]

We report a method to promote solid source growth of Si oxide nanowires (SiONWs) by using an array of vertically aligned carbon nanotubes (CNTs). It starts with the fabrication of CNT array by plasma enhanced chemical vapor deposition (PECVD) on Si wafers, followed by growth of SiONWs. Herein, CNTs serve as a scaffold, which helps the dispersion of catalysts for SiONWs and also provides space for hydrogen which boosts the diffusion of Si atoms and hence formation of SiONWs. As the result, a three dimensional (3D) hybrid network of densely packed SiONWs and CNTs can be produced rapidly. [ABSTRACT FROM AUTHOR]