Heterogeneous, Porous 2D Oxide Sheets via Rapid Galvanic Replacement: Toward Superior HCHO Sensing Application. (19th July 2019)

• Record Type: Journal Article
• Authors: Jang, Ji‐Soo; Lee, Sang‐Eun; Choi, Seon‐Jin; Koo, Won‐Tae; Kim, Dong‐Ha; Shin, Hamin; Park, Hee Jung; Kim, Il‐Doo
• Is Part Of: Advanced functional materials. Volume 29:Number 42(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-07-19
• Subjects: exfoliation -- galvanic replacement -- gas sensors -- porosity; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.201903012
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: 2D heterogeneous oxide nanosheets (NSs) have attracted much attention in various scientific fields owing to their exceptional physicochemical properties. However, the fabrication of 2D oxide NSs with abundant p–n interfaces and large amounts of mesopores is extremely challenging. Here, a facile synthesis of highly porous 2D heterogeneous oxide NSs (e.g., SnO2 /CoO x ) is suggested through a 2D oxide exfoliation approach combined with a fast galvanic replacement reaction (GRR). The ultrathin (<5 nm) layered CoO x NSs are simply prepared by ion‐exchange exfoliation and a subsequent GRR process that induces a rapid phase transition from p‐type CoO x to n‐type SnO2 metal oxides (<10 min). The controlled GRR process enables the creation of heterogeneous SnO2 /CoO x NSs consisting of small SnO2 grain sizes (<10 nm), high porosity, numerous heterojunctions, and sub‐10 nm thickness, which are highly advantageous characteristics for chemiresistive sensors. Due to the advantage of these features, the porous SnO2 /CoO x NSs exhibit an unparalleled HCHO‐sensing performance ( R air / R gas > 35 @ 5 ppm with a response speed of 9.34 s) with exceptional selectivity compared to that of the state‐of‐the‐art metal oxide‐based HCHO gas sensors. Abstract : Highly porous heterogeneous SnO2 /CoO x 2D nanosheets are successfully achieved by exfoliation combined with a galvanic replacement reaction. The thin‐walled (<5 nm) exfoliated p‐type CoO x nanosheets are transformed into porous, thin‐walled (<10 nm) n‐type SnO2 nanosheets via galvanic replacement. The porous SnO2 /CoO x 2D nanosheets show superior HCHO‐sensing performance with stable mechanical flexibility compared to reported state‐of‐the‐art HCHO sensors.