Modulation of VO2 metal-insulator transition by co-doping of hydrogen and oxygen vacancy

As a well-known thermochromic material, Vanadium dioxide (VO2) has drawn widespread interest due to its particular phase transition feature. Many endeavors have been implemented to decrease critical temperature in order to realize VO2-based smart window, while there is still much room to improve. Herein, we provide a facile way to control the critical temperature of VO2 by co-introducing of hydrogen and oxygen vacancy while without deteriorating its original metal-insulator transition behavior. SIMS was carried out to detect the depth profile of hydrogen element, and XPS was conducted to investigate the chemical state. Based on the first-principle calculation, it was found that the hydrogen played a crucial role on the structural evolution of VO2. For seldom hydrogen doping, rutile-like VO2 with metallic state was formed, in agreement with the XRD observation. Strikingly, it transformed into a more monoclinic structure as further introducing hydrogen atoms. In addition, the energy-efficient demonstration experiment exhibited a promising application for VO2 material in energy-saving field. The current findings offer a novel strategy to modulate the critical temperature of VO2, which will promote the development of VO2 in smart window and bring insight into comprehensive understanding the role of H in VO2 phase transition process.