Modulating surficial oxygen vacancy of the VO2 nanostructure to boost its electromagnetic absorption performance

Abstract

Endowing a transition metal oxide (TMO) with oxygen vacancy is an efficient strategy to tune its electronic structure and electric properties. In this work, we put forward an exquisite VO₂–NaBH₄ grinding treatment for the tuning of surficial oxygen vacancy of VO₂ nanostructures under ambient conditions, and systematically investigate the electromagnetic absorption (EMA) properties of treated VO₂. Electron paramagnetic resonance (ESR) spectroscopy and X-ray photoelectron spectroscopy (XPS) demonstrate that the formation of oxygen vacancy occurs via the reaction of H⁻ in NaBH₄ with surficial V–O–H of VO₂. First-principles simulations and experimental results reveal the correlation between oxygen vacancy and electrical conductivity. It is found that the EMA performance of VO₂ is closely associated with its oxygen vacancy content and can be efficiently regulated by tuning the mass ratio of VO₂ and NaBH₄. Enhanced electrical conductivity and improved polarization relaxation are thought to be the main reasons for the enhanced EMA performance. This research provides a new idea for the tuning of surficial oxygen vacancy as well as the design of novel EMA materials.