Jem 2010 uhr

To observe uranium-bearing loci by TEM, we fabricated electron-transparent ultrathin sections with a focused ion beam (FIB) sample preparation technique using a Hitachi FB-2100 instrument (Ibaraki, Japan) with a micro-sampling system. Before FIB fabrication, the thin section sample was coated by a carbon film and inserted into the FIB apparatus, then locally coated with the deposition of W (100–500 nm thick) for protection, trimmed using a Ga ion beam at an accelerating voltage of 30 kV and thinned down to a final thickness of 100–200 nm with a low energy beam of 10 kV as a final process. FIB-fabricated ultrathin sections were placed on a Cu specimen support with W deposition and observed by TEM. TEM examinations were performed at an accelerating voltage of 200 kV using a JEOL JEM-2010 UHR (LaB₆ electron gun) with a nominal point resolution of ~0.2 nm. TEM-EDS was used for elemental analysis of U-bearing nanoparticles and Mg- and Fe-bearing aluminosilicate.

The microstructure and composition of GO/PDA and GO/PDA/Cu NPs were characterized by TEM (JEM-2010 UHR, JEOL) and XPS (ESCALAB 250, Thermo Fisher Scientific) using the Al Kα radiation (1486.6 eV, 15 kV, 150 W) at a vacuum of 2×10⁻⁹ mbar. Electrochemical measurement was performed at room temperature in phosphate buffer (PBS) on the CHI 660e potentiostat (CH Instruments Inc., Shanghai, China). A simple three-electrode configuration used in the measurement consisted of an Ag/AgCl electrode as the reference electrode, a Pt wire as the counter electrode, and a glassy carbon electrode (GCE, 3 mm in diameter) modified with GO/PDA/Cu NPs composite as the working electrode.

The electrodes morphologies were examined by field emission scanning electron microscopy (FESEM, Hitachi S4700, and SUPRA 40VP) equipped with an energy dispersive X-ray (EDX), and high-resolution transmission electron microscopy (HRTEM, JEOL JEM-2010UHR) with selected area electron diffraction (SAED) at an acceleration voltage of 200 kV. The crystalline structure of as-synthesized ZNRs was analyzed using X-ray diffractometer (XRD, Rigaku) with Cu-Kα radiation (λ = 1.54178 Ǻ) in the range of 10–90° with 8°/min scanning speed. In addition, the optical properties of ZNRs were characterized by Raman-scattering measurements with Ar⁺ (513.4 nm) as the exciton source.