Fig. 5: In situ XPS characterization with weak current applied by electron gun.

a, b Schematics of the in situ XPS cell created in-house for electrified binding energy deflection, with front (a) and top-view (b). c, d In situ XPS results during different binding energies 522–512 eV (c) and 500–482 eV (d). The 2VNA sample was tableted, and different current were applied under vacuum conditions, the operating voltages of 0, 2, 4, and 6 V correspond to the currents of 0, 1.35, 12, and 22.8 μA on the sample surface, respectively.