A facile strategy to realize rapid and heavily hydrogen-doped VO2 and study of hydrogen ion diffusion behavior

Heavily hydrogen-doped VO2 has drawn broad interest due to the modulation of versatile electronic phase transition and structural transition, while it is still challenging for highly efficient and fast hydrogen incorporation in VO2. Herein, we provide a facile approach to achieving rapid and high-concentration hydrogen-doped VO2 preparation. The as-prepared VO2 film instantaneously converted to a partially metallic phase once it was immersed into NaBH4 solution due to the introduction of a light hydrogen dopant. Strikingly, high-concentration hydrogen incorporation into VO2 was achieved as the solution temperature increased over the phase transition temperature. Based on the first-principles calculation, we investigated the diffusion behaviors of hydrogen in M-VO2 and R-VO2 that migrated from the surface to the subsurface and in bulk. The detailed formation energy calculation suggested that the presence of R-VO2 was beneficial to realize heavily H-doped VO2, while the thermodynamic property accelerated the reaction process. The current findings not only supplied a novel strategy to realize fast and high-concentration hydrogen incorporation in VO2, shedding light on hydrogenated metal oxide materials, but also brought insight into a comprehensive understanding of hydrogen diffusion behavior in VO2.