Fig. 3: Depth profiling of the LPO-NMC811 and the PS-LPO-NMC811 samples.

a Schematic of synchrotron-based high energy XPS with tunable energy. b P 1 s and c O 1 s HEXPS spectra of the LPO-NMC811 sample at different photon energies of 3000 (blue lines), 6000 (red lines), and 8000 (green lines) eV. d S 1 s, e P 1 s, and f O 1 s HEXPS spectra of the PS-LPO-NMC811 sample at different photon energies of 3000 (blue lines), 6000 (red lines), and 8000 (green lines) eV.