Oxide/ZIF‐8 Hybrid Nanofiber Yarns: Heightened Surface Activity for Exceptional Chemiresistive Sensing. Issue 10 (31st January 2022)

• Record Type: Journal Article
• Authors: Kim, Dong‐Ha; Chong, Sanggyu; Park, Chungseong; Ahn, Jaewan; Jang, Ji‐Soo; Kim, Jihan; Kim, Il‐Doo
• Is Part Of: Advanced materials. Volume 34:Issue 10(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-01-31
• Subjects: gas sensors -- metal–organic frameworks -- molecular sieves -- nanofiber yarns -- surface activity; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.202105869
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: Though highly promising as powerful gas sensors, oxide semiconductor chemiresistors have low surface reactivity, which limits their selectivity, sensitivity, and reaction kinetics, particularly at room temperature (RT) operation. It is proposed that a hybrid design involving the nanostructuring of oxides and passivation with selective gas filtration layers can potentially overcome the issues with surface activity. Herein, unique bi‐stacked heterogeneous layers are introduced; that is, nanostructured oxides covered by conformal nanoporous gas filters, on ultrahigh‐density nanofiber (NF) yarns via sputter deposition with indium tin oxide (ITO) and subsequent self‐assembly of zeolitic imidazolate framework (ZIF‐8) nanocrystals. The NF yarn composed of ZIF‐8‐coated ITO films can offer heightened surface activity at RT because of high porosity, large surface area, and effective screening of interfering gases. As a case study, the hybrid sensor demonstrated remarkable sensing performances characterized by high NO selectivity, fast response/recovery kinetics (>60‐fold improvement), and large responses (12.8‐fold improvement @ 1 ppm) in comparison with pristine yarn@ITO, especially under highly humid conditions. Molecular modeling reveals an increased penetration ratio of NO over O2 to the ITO surface, indicating that NO oxidation is reliably prevented and that the secondary adsorption sites provided by the ZIF‐8 facilitate the adsorption/desorption of NO, both to and from ITO. Abstract : A multifunctional chemiresistive gas sensor composed of nanofiber yarn sputter‐deposited with indium tin oxide (ITO) as a sensing layer is designed, and then coated with zeolitic imidazolate framework (ZIF‐8) for nanofiltration of gas analytes. Through comprehensive sensing experiments and molecular modeling, it is demonstrated that yarn@ITO@ZIF‐8 exhibits highly sensitive and selective sensing properties toward NO at room temperature with accelerated responding speeds.