Tecnai f30 instrument

Following thermal evaporation of 6–10 nm of amorphous carbon on the sample for improved conductivity, a thin device cross-section lamella was prepared using a focused Ga-ion beam in a FEI Helios DualBeam machine. HR-TEM imaging was performed using an FEI Tecnai F-30 instrument. The lamella was exposed to air for < 5 min during transfer to the HR-TEM. Images were acquired at a working voltage of 300 kV. Inter-layer distances of different strata in the hBN/BP/hBN stack were obtained from fast Fourier transform of selected areas in the device cross-section. Elemental mapping of the device cross-section was performed using electron energy loss spectroscopy in combination with a Gatan imaging filter, yielding an energy-filtered transmission electron microscopy image.

All the chemicals are of analytical reagent grade and used without further purification. Citric acid monohydrate, ethylenediamine, dimethylsulfoxide (DMSO), copper chlorophyllin, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC), N-hydroxysulfosuccinimide sodium salt (S-NHS), ethanol and silver nitrate (AgNO₃) were purchased from Sinopharm Chemical Reagent Co. Ltd.
The UV-Vis absorptions were measured with a Cary-60 UV-Vis spectrophotometer (Agilent, USA). The FL spectra of the samples in quartz cells were measured on a Cary Eclipse fluorescence spectrophotometer (Agilent, USA) using a Xe lamp as the excitation source in the same condition of measurements. The transmission electron microscope (TEM) images were captured on a Tecnai F30 instrument (FEI, USA). The X-ray powder diffraction (XRD) analysis was performed on an AXS-D2 diffractometer (Bruker, Germany) with Cu Kα radiation (λ = 1.5406 Å). The Cu²⁺ content in CCPh-CDs was measured by an Agilent-7900cx inductively coupled plasma mass spectrometer (ICP-MS). The decay lifetimes of the samples were measured at room temperature using an FLS920 lifetime spectrofluorophotometer.

Magnetite nanoparticles (Magnetite) were synthesized via coprecipitation by mixing 20 mL of 1M FeCl₂ and 20 mL 2M FeCl₃ under agitation at 1500 revolutions per minute (rpm) and 90 °C. Subsequently, 40 mL of 8M NaOH and 40 mL 2% (v/v) of TMAH were added to the mixture during 3.5 h at a flow rate of 12 mL/h. The obtained magnetite nanoparticles were purified by magnetic separation with the aid of a strong permanent magnet, then washed thoroughly with 2% (v/v) TMAH, and finally sonicated for 100 min using a VibraCell sonication system (Sonics, Newtown, CT, USA). The synthesized Magnetite exhibited an average hydrodynamic diameter of 88.59 nm with a polydispersity index of 0.182 as determined by Dynamic Light Scattering (DLS) analysis with the aid of a Zetasizer Nano ZS, (Malvern, UK) as previously reported by Lopez-Barbosa et al. (2020) [37 (link)]. Microscopic inspection of the Magnetite structure, morphology, and shape was achieved via transmission electron microscopy (TEM) in a Tecnai F30 instrument (FEI Company, Fremont, CA, USA)