Manipulating the Defect Structure (VO) of In2O3 Nanoparticles for Enhancement of Formaldehyde Detection.

Because defects such as oxygen vacancies (VO) can affect the properties of nanomaterials, investigating the defect structure-function relationship are attracting intense attention. However, it remains an enormous challenge to the synthesis of nanomaterials with high sensing performance by manipulating VO because understanding the role of surface or bulk VO on the sensing properties of metal oxides is still missing. Herein, In2O3 nanoparticles with different contents of surface and bulk VO were obtained by hydrogen reduction treatment, and the role of surface or bulk VO on the sensing properties of In2O3 was investigated. The X-ray diffraction, ultraviolet-visible spectrophotometer, electron paramagnetic resonance, photoluminescence, Raman, X-ray photoelectron spectroscopy, Hall analysis, and the sensing results indicate that bulk VO can decrease the band gap and energy barrier and increase the carrier mobility, hence facilitating the formation of chemisorbed oxygen and enhancing the sensing response. Benefiting from bulk VO, In2O3-H10 exhibits the highest response, good selectivity, and stability for formaldehyde detection. However, surface VO does not contribute to the improvement of formaldehyde-sensing performance, and the black In2O3-H30 with the highest content of surface VO exhibits the lowest response. Our work provides a novel strategy for the synthesis of nanomaterials with high sensing performance by manipulating VO.