Self-Stabilization Effect and Selective-Area Effect in Electron–Proton Synergistic Doping

Hydrogenation is an effective way to tailor the properties of various oxides. Subject to high-energy environments, it is costly and subtle for conventional hydrogenations to control the concentrations and spatial distributions of the doped hydrogen atoms. Recently, we have been developing a low-energy hydrogenation technology, electron–proton synergistic doping by metal–acid treatment, whose advances of the self-stabilization effect and selective-area effect would be demonstrated in this report. The self-stabilization effect suggests that doped concentrations can be realized by adopting different reactive metals regardless of reaction periods. As a representative example by the selective-area effect, the planar tri-state coexistence in the VO2 film is achieved for the first time. Finally, a promising physical–chemical mechanism involving the work function and electrode potential of the applied reactive metals is proposed to explain electron–proton synergistic doping successfully.