Oneview camera

All TEM investigations were performed with a double aberration-corrected JEOL ARM 200F microscope operated at 200 kV. This microscope is equipped with a high brightness cold eld emission source, a JEOL SDD EDX detector and a One View camera (Gatan Inc.). 21, 32 Particle characterizations were performed in both TEM and STEM modes. In the latter, STEM high angle annular dark eld (HAADF) images were acquired with spot size setting 8 which corresponds to a probe size of around 0.08 nm. The convergence semi-angle was set to 20.5 mrad while the annular collection angle was set between 68 and 280 mrad in order to minimize diffraction contrast. The elemental composition of the HENA was quantied both on NP assemblies and at single particle level by energy-dispersive X-ray (EDX) spectroscopy. EDX spectra of single NPs were acquired in 1 minute by scanning the electron beam over a rectangular area.

Bi2Se3-WS2 2D heterostructures were transferred onto a holey amorphous SiNx TEM grid using the water-assisted-pick-up transfer method. 44 (link) Bright-field imaging, high-resolution TEM (HRTEM) and selected area electron diffraction (SAED) were performed with a JEOL JEM2200FS operating at 200 kV, equipped with a high-speed Gatan OneView camera. The HRTEM images were acquired at selected regions-of-interest as rapidly as possible to minimize sample alteration from the electron beam. The SAED patterns were internally calibrated to the WS2, and an aperture of approximately 200nm was used.
Atmospheric measurements: Atmospheric measurements were conducted inside a Janis ST-500 with vacuum, air, N2 and O2 connections. Figure 4 applied a 38.8µW 532nm laser without interruption at a 50x long working distance objective (1.65µW/µm 2 ). Spectra were measured at various intervals with a 0.8 sec. collection time. Figure 5 and Section S6 applied 84.7 µW 588nm laser without interruption at a 50x long working distance objective. Spectra were measured at various intervals with a 0.4 sec. collection time.