Hd 2300a

To make an aqueous solution, KI powder (0.002 mol, Sigma-Aldrich, Seoul, Korea) and 10 mL of Au NPs (3 nM, particle size = 20 nm, Sigma-Aldrich, Seoul, Korea) dispersed in H₂O were mixed in 80 mL of deionized water. Subsequently, 20 mL of 30% aqueous SMS (Gelest, Morrisville, PA, USA) was added to the mixed solution. In order to mix the solution properly, the aqueous solution was stirred magnetically at 85 °C on a hot plate. Then, samples were prepared by dropping aqueous solution onto the Si substrate. All samples were cooled down 4 °C or room temperature (RT), or maintained at 70 °C over 24 h until the solution droplets dried. The structural, compositional, and optical properties of the samples were investigated using scanning electron microscopy (SEM, SU-8230, Hitachi, Japan), energy-dispersive X-ray spectrometry (EDX, SU-8230, Hitachi, Japan), X-ray diffraction (XRD, X’pert Pro Powder, PANalytical, Netherlands), transmission electron microscopy (TEM, HD-2300A, Hitachi, Japan), and PL (SpectraPro 500i, Acton, USA). To further investigate the growth mechanism of the a-Si nanotips on the Si substrate, focused ion beam (FIB)-SEM (FB-2100, Hitachi, Japan) and atomic force microscopy (AFM, MOD-1M series, Nanofocus, Richmond, VA, USA) analyses were also performed.

Morphologies and elemental distributions were probed by field-emission scanning transmission electron microscopy (FE-STEM; HD-2300A, Hitachi, Japan) at an operating voltage of 200 kV. Individual elements were identified by electron energy loss spectroscopy (EELS; JEM-ARM200F, JEOL, Japan). Crystalline phases were identified by XRD analysis (Ultima IV, Rigaku, Japan). Nanocomposite graphitization degree, irregularities, and imperfections were characterized by Raman spectroscopy (VERTEX 80v, Bruker, Korea). Surface chemical states were identified by X-ray photoelectron spectroscopy (XPS; Kratos Analytical Ltd., Axis Supra, UK). The absolute metal contents of carbon catalysts were probed by inductively coupled plasma optical emission spectrometry (Optima 8300, Perkin Elmer, USA). Fe K-edge- and Co K-edge-extended X-ray absorption fine structure (EXAFS) spectra were recorded according to fluorescent patterns using the TPS 44A1 beamline (situated in the National Synchrotron Radiation Research Center (NSRRC) of Taiwan, China) at an energy of 3 GeV and an average current of 250 mA [41 (link)]. The radioactive ray was monochromatized by a monochromator with Si (111) bicrystal. X-ray absorption near-edge structure (XANES) and EXAFS data reduction and analysis were performed using Athena software [41 (link)].

All SMPs were characterized by transmission electron microscopy (TEM, Hitachi HT-7700, 120 KV, or STEM, Hitachi HD-2300A, 200 KV). Dynamic light scattering (DLS, Malvern Instruments Ltd, Nano ZS), zeta-potential (Malvern Instruments Ltd, Nano ZS), and ultraviolet-visible spectroscopy (UV-Vis, Agilent Technologies Cary 100 UV-Vis) were used to investigate hydrodynamic diameters.

Scanning transmission electron microscopy (STEM) (Hitachi HD-2300A) was used to study the surface morphology of the NSA-SLNs. For this, a drop of diluted SLN was placed on the gold grids and any excess dispersion on the gold grid was wicked using filter paper. Then, the grid was placed for drying in a sterile fume hood for two days. Finally, the sample grid was transferred into the STEM and high-resolution images were recorded in secondary electron (SE) image mode at an accelerated voltage of 200 kV.