Gemini500 field emission sem

The primary particle length of the NPs was measured using high-resolution scanning electron microscopy (HR-SEM). Three to four milligrams of the four pristine TiO₂ NP powders (T-S, T-Lite, T-AVO, P25 TiO₂) were dispersed on carbon adhesive tape and analyzed using a Zeiss Gemini500-Field emission SEM. To obtain surface-sensitive imaging at nanoscale resolution, images were recorded at low voltage (1–5 kV) with an in-lens secondary electron detector. Image analysis was then completed in order to distinguish the smallest particulate units constituting the powder grains. The primary particle lengths were obtained from the largest dimension of these smallest units. Fifty particles per sample were measured in order to calculate an average primary particle length.

To determine average AuNP core size, high-resolution scanning electron microscopy (SEM) images were taken of AuPS27 and AuPS53 monolayer films deposited on Si substrates. SEM images were acquired using a Gemini 500 field emission SEM (Carl Zeiss AG, Oberkochen, Germany) at an acceleration voltage of 5 kV. A representative image of AuPS27 monolayer film is shown in Figure S13a. Custom image analysis software written using Matlab 2018b (Mathworks) was applied to determine the radius of each AuNP in the image. A small number of outliers consisting of nanoparticle dimers were automatically excluded from the analysis. The resulting distribution of AuNP radii is shown in Figure S13b, giving an average radius of (9.9 ± 1.0) nm.

The visualization of NAC particles was done by LEICA DFC 3000 G bright field microscope. Samples were placed on the microscope slide and a 50 : 50 solution of glycerol and water was added to wet the samples and provide the contrast for core–shell identification. Photos of samples were taken before and after wetting. To observe the morphology of NAC coated particles, scanning electron microscopy (SEM) micrographs were taken for selected coated samples from NAC powder, NAC crystals, and NAC granules. A Zeiss Gemini 500 Field Emission SEM was used to do this. Before being mounted on the SEM machine, all of the samples were coated with an ultra-thin gold layer using a sputter coater.