Hydrogen Sensors Based on MoS 2 Hollow Architectures Assembled by Pickering Emulsion.

For rapid hydrogen gas (H ₂ ) sensing, we propose the facile synthesis of the hollow structure of Pt-decorated molybdenum disulfide (h-MoS ₂ /Pt) using ultrathin (mono- or few-layer) two-dimensional nanosheets. The controlled amphiphilic nature of MoS ₂ surface produces ultrathin MoS ₂ NS-covered polystyrene particles via one-step Pickering emulsification. The incorporation of Pt nanoparticles (NPs) on the MoS ₂ , followed by pyrolysis, generates the highly porous h-MoS ₂ /Pt. This hollow hybrid structure produces sufficiently permeable pathways for H ₂ and maximizes the active sites of MoS ₂ , while the Pt NPs on the hollow MoS ₂ induce catalytic H ₂ spillover during H ₂ sensing. The h-MoS ₂ /Pt-based chemiresistors show sensitive H ₂ sensing performances with fast sensing speed (response, 8.1 s for 1% of H ₂ and 2.7 s for 4%; and recovery, 16.0 s for both 1% and 4% H ₂ at room temperature in the air). These results mark the highest H ₂ sensing speed among 2D material-based H ₂ sensors operated at room temperature in air. Our fabrication method of h-MoS ₂ /Pt structure through Pickering emulsion provides a versatile platform applicable to various 2D material-based hollow structures and facilitates their use in other applications involving surface reactions.