Parts-per-Million Detection of Volatile Organic Compounds via Surface Plasmon Polaritons and Nanometer-Thick Metal–Organic Framework Films

• Published in: ACS applied nano materials 2022-04, Vol.5 (4), p.5006-5016
• Main Authors: Tietze, Max L, Obst, Martin, Arnauts, Giel, Wauteraerts, Nathalie, Rodríguez-Hermida, Sabina, Ameloot, Rob
• Format: Article
• Language: English
• ISSN: 2574-0970; 2574-0970
• DOI: 10.1021/acsanm.2c00012

Because of their guest adsorption properties, metal–organic frameworks (MOFs) are promising materials to realize chemical sensors. However, achieving high sensitivities requires the reproducible deposition of well-defined MOF films and their integration with a suitable sensor design. In this work, we report the sensitive detection of volatile organic compounds (VOCs) by transducing the adsorption in zeolitic imidazolate framework 8 (ZIF-8) thin films, prepared by chemical vapor deposition (MOF-CVD), into surface plasmon polariton (SPP) shifts measured via total internal reflection ellipsometry (TIRE). It is shown that defect formation during MOF-CVD alters the VOC uptake. However, SPP resonances tunable over the entire Vis–NIR range and as sharp as 14 nm are obtained for optimized synthesis conditions. Record-breaking shifts stronger than 150 nm upon methanol uptake and a limit of detection below 1 ppm are observed. By modeling the TIRE spectra, changes in the ZIF-8 refractive index from 1 × 10–4 (single-digit ppm VOC concentration) up to 0.06 are resolved with a resolution better than 1 × 10–5.