XPS spectra has been widely used to identify the existence of
a particular element and distinguish their different forms in the
material. When the chemical environment of the atoms changed
due to specific interactions, the binding energy of atoms would
change or a development of a new peak with a higher binding
energy would appear [27]. To investigate the adsorption mechanism
of interest ions on the self-prepared H2Dz-SCMNPs, XPS
spectra of the prepared materials before and after extraction of
heavy metal ions were obtained, as shown in Fig. 5A. Fig. 5B–G is