title: Stable and Selective Humidity Sensing Using Stacked Black Phosphorus Flakes.
abstract: Black phosphorus (BP) atomic layers are known to undergo chemical degradation in humid air. Yet in more robust configurations such as films, composites, and embedded structures, BP can potentially be utilized in a large number of practical applications. In this study, we explored the sensing characteristics of BP films and observed an ultrasensitive and selective response toward humid air with a trace-level detection capability and a very minor drift over time. Our experiments show that the drain current of the BP sensor increases by ∼4 orders of magnitude as the relative humidity (RH) varies from 10% to 85%, which ranks it among the highest ever reported values for humidity detection. The mechanistic studies indicate that the operation principle of the BP film sensors is based on the modulation in the leakage ionic current caused by autoionization of water molecules and ionic solvation of the phosphorus oxoacids produced on moist BP surfaces. Our stability tests reveal that the response of the BP film sensors remains nearly unchanged after prolonged exposures (up to 3 months) to ambient conditions. This study opens up the route for utilizing BP stacked films in many potential applications such as energy generation/storage systems, electrocatalysis, and chemical/biosensing.
authors.forename: Poya
authors.initials: P
authors.lastname: Yasaei
authors.forename: Amirhossein
authors.initials: A
authors.lastname: Behranginia
authors.forename: Tara
authors.initials: T
authors.lastname: Foroozan
authors.forename: Mohammad
authors.initials: M
authors.lastname: Asadi
authors.affiliation: Department of Mechanical Engineering, Chungbuk National University , Cheongju, 361-763, South Korea.
authors.forename: Kibum
authors.initials: K
authors.lastname: Kim
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Khalili-Araghi
authors.forename: Amin
authors.initials: A
authors.lastname: Salehi-Khojin
mesh_terms: D000388:Air / Q000032:analysis*; D006813:Humidity; D007477:Ions / Q000737:chemistry; D010758:Phosphorus / Q000737:chemistry*; D013227:Steam / Q000032:analysis*
chemical_list: D007477:Ions; D013227:Steam; D010758:Phosphorus
keywords: black phosphorus; humidity sensing; liquid-phase exfoliation; phosphorene; two-dimensional (2D) materials