Nanonova 450

The morphology of tourmaline nanoparticles (TM NPs) after ball milling was observed by a scanning electron microscope (SEM, NanoNova 450, FEI, USA). The crystal structure of TM NPs was detected by X-ray diffraction (XRD, D8 Advance, Bruker, Germany). At the same time, the TM particles were dispersed in an alcohol solution by ultrasonic agitation for 0.5 h and the zeta potential of the samples were tested using a Malvern Nano ZS90 (UK).

FESEM (FEI Nano Nova 450) was used to observe the morphologies of the samples at a low voltage of 5 or 3 kV. To protect the microstructure of the NCD films from damage during TEM sample preparation, small fragments of film were scraped down from the silicon substrate and loaded on copper mesh. The submicroscopic structures or ultrastructures of the samples were characterized by using HRTEM (FEI Talos-s, 200 kV accelerator voltage) and aberration‐corrected scanning transmission electron microscopy (Titan G2 80-200 ChemiSTEM). EDS and EELS were used to recognize the composition information of the samples. Raman spectra were taken to evaluate the structure and components of the films. A Labram high-resolution spectrometer (Horiba Jobin-Yvon) interfaced with an Olympus microscope (objective 50×) was used to acquire the Raman spectra for four different sites, and the spectra were collected in the range of 500 to 3,500 cm⁻¹. Some of the spectra had been deconvoluted well into Gaussian lines.

SEM (Nano nova 450, FEI, USA) was used to acquire microphotographs on the surface and cross-section of the samples SN-38, Na₂GA, Na₂GA/SN-38-BM, and Na₂GA/SN-38-UM. Dual adhesive was used to place the four samples onto the metal stubs and then the samples were gold-coated before imaging by electron microscopy.