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[Display omitted] • Synthesis of atomically thin 2D metal oxide NSs by a chemical exfoliation process. • A comparative study on the humidity sensing performances of 2D Ru oxide and Mn oxide NSs. • Demonstration of real-time breath humidity monitoring using a wearable sensing module. Collecting real-time breath humidity data is important for calibrating gas sensors from interfering signals in breath components, ultimately for accurately monitoring a patient's physiological information for applications in non-invasive and point-of-care diagnostics. In this work, atomically thin 2D metal oxide nanosheets (NSs) were synthesized by a liquid phase exfoliation process and their humidity sensing properties were investigated. Interestingly, Opposite humidity sensing responses (R D /R H) were observed between semiconducting oxide and metallic oxide NSs. For the semiconducting manganese (Mn) oxide NSs, decreasing resistance transitions were obtained with the response of 24.01 at 44.5% RH at low humidity levels (i.e., 6.1–45% RH), which was governed by proton (H+) conduction. On the other hand, the metallic ruthenium (Ru) oxide NSs exhibited increasing resistance transitions with the response of 0.28 at 96.3% RH at a high humidity range (i.e., 50–99.9% RH) as a result of proton trapping by accepting electrons upon the exposure to excess water molecules. Ru oxide NSs exhibited the response and recovery times of 68 sec and 8 sec, respectively, at 96.3% RH. Real-time breath humidity monitoring is demonstrated by integrating Ru oxide NSs with a wristband-type wireless sensing module, which can transmit the sensing data to a mobile device. [ABSTRACT FROM AUTHOR]

Silicon-coated molybdenum sulfide nanosheets were prepared in a thin-film shape (Si–MoS 2 TFs) through metal organic chemical vapor deposition (MOCVD) and radio frequency (RF) sputtering. By using MOCVD, the MoS 2 thin films composed of nanosheets were vertically grown on stainless steel substrates. To address the problem of polysulfide dissolution and shuttling effect of MoS 2 during discharge and charge reactions in thin-film Li-ion batteries, the entire surfaces of MoS 2 TFs were covered with silicon layers using RF sputtering. Compared with pristine MoS 2 TFs without protection, the Si–MoS 2 TFs showed excellent reversibility with a high capacity of ∼2000 mAh g−1 for 500 cycles in thin-film Li-ion batteries. Both materials – MoS 2 and Si – were synergistically taken into account to enhance the ability to store Li ions in the host structures and complement each other during repeated conversion and alloying reactions. The underlying reaction principle was elucidated, which provides insight into developing MoS 2 -based thin-film cathodes. [ABSTRACT FROM AUTHOR]

Lightweight and ultrathin materials with superior electromagnetic interference (EMI) shielding performance are highly desirable for next-generation electronic devices. Herein, we fabricate a lightweight, thin, and flexible composite film, composed of Ti 3 C 2 T x MXene and nanoparticles of Galinstan liquid metal, by simple vacuum-assisted filtration as a promising candidate for EMI shielding. The resultant composite film with highly conductive liquid metal between the MXene nano sheets exhibits enhanced electrical conductivity (4955 S cm−1), superior EMI shielding effectiveness (66.28 dB), and an absolute shielding effectiveness (15,029 dB cm2 g−1) at a thickness of 15 μm in the X-band (8.2–12.4 GHz) frequency range that is one of the highest among those of MXenes hybrid composites. [Display omitted] • Lightweight and ultrathin EMI shielding materials were fabricated. • MXene-Galinstan liquid metal hybrid yields superior electrical conductivity. • It exhibited shielding effectiveness of 66.3 dB and an absolute shielding effectiveness of 15,029 dB cm2 g−1. • Such properties attributed to the bridging effect of liquid metal in the hybrid. [ABSTRACT FROM AUTHOR]