Samples were drop-cast onto copper grids with a lacey carbon support film after sonicating the sample suspension in methanol. Energy dispersive X-ray spectroscopy (EDS) data were measured on a Thermo Fisher Scientific Talos F200i equipped with a Bruker Dual-X spectrometer, operated in the STEM regime at a high voltage of 200 kV and beam current of 0.5 nA. Spectra and images were post-processed by the Velox software.