Fig. 3: Identification of the chemical composition of the water-induced passivation layer.

a, b SEM images and (c) TOF-SIMS spectra of MgOH-, MgO-, and MgH- ion obtained from pristine Mg electrode before and after 30 mins of the water treatment. d TOF-SIMS depth profiles and 3D render images of MgOH-, MgO-, and MgH- for pristine Mg electrodes after 30 min of the water treatment. e, f SEM images and (g) TOF-SIMS spectra of MgOH-, MgO-, and MgH- ion obtained from PDG-Mg electrode before and after the water treatment. h TOF-SIMS depth profiles and 3D render images of MgOH-, MgO-, and MgH- for PDG-Mg electrodes after 30 min of the water treatment.