Humidity sensing is crucial for food production, environmental monitoring, microelectronic manufacture, and common living conditions. Thus, there is a high demand for development of high-performance humidity sensors with good stability, high precision and fast responses. In this study, Love wave mode humidity sensors were prepared using quartz-based SAW devices coated with composite sensing layers of accordion-like Ti 3 C 2 T x , MoS 2 nanoflowers and MoS 2 @Ti 3 C 2 T x hierarchical structure, respectively. The hydrophilic Ti 3 C 2 T x was used to provide abundant surface functional groups for adsorption of water molecules, and the hydrophobic MoS 2 enabled rapid adsorption and desorption of water molecules from the surface of MoS 2 @Ti 3 C 2 T x . The MoS 2 @Ti 3 C 2 T x coated Love wave humidity sensor presented an ultra-high sensitivity of 0.67 kHz/% RH in the wide humidity range from 11.3% RH to 97.3% RH, mainly attributed to the hierarchical structure of MoS 2 @Ti 3 C 2 T x with large specific surface areas, abundant adsorption sites and superhydrophilicity. Meanwhile, this Love wave humidity sensor showed fast response/recovery rates, great repeatability and long-term stability, indicating its great prospects in humidity detection applications.
Jiapeng Liu,Yizhe Liu,Danyun Xu,Yuanzhi Zhu,Wenchao Peng,Yang Li,Fengbao Zhang,Xiaobin Fan
Developing highly efficient noble-metal-free electrocatalysts for hydrogen evolution reaction (HER) has attracted increasing attentions. Here, we report a simple strategy to synthesize the hierarchical “nanoroll” like MoS 2 /Ti 3 C 2 T x hybrid by combining liquid nitrogen-freezing and subsequent annealing. The quick freezing of the Ti 3 C 2 T x nanosheets and ammonium tetrathiomolybdate mixture causes a sudden change in the strain of Ti 3 C 2 T x , which leads to an interesting “nanoroll” like hierarchical structure. After annealing at H 2 /Ar atmosphere, vertically aligned molybdenum sulfide (MoS 2 ) crystallites are in situ formed in and on the nanoroll like Ti 3 C 2 T x . Notably, this hierarchical MoS 2 /Ti 3 C 2 T x hybrid exhibits excellent HER catalytic activity with a small onset overpotential of 30 mV, and a more than 25-fold increase in the exchange current density compared with MoS 2 was observed.
Simple and effective synthesis methods for 2D/2D heterostructure and the synergistic effect of 2D/2D composites on microwave absorbing (MWA) performance remain to be further explored and investigated. Herein, 2D/2D MoS 2 /Ti 3 C 2 T x heterostructure was successfully synthesized in 30 min by a cost-effective and time-saving microwave-assisted hydrothermal method . The 2 H-MoS 2 nanosheets with a thickness of 5–10 nm were homogeneously anchored on the surface of Ti 3 C 2 T x layers, showing a tunable distribution density. Besides, the metallic properties of MoS 2 /Ti 3 C 2 T x and the strong interaction between MoS 2 and Ti 3 C 2 T x , were revealed by DFT calculations, which was employed to further understand the MWA mechanism in terms of molecular dynamics. The MoS 2 /Ti 3 C 2 T x composites with an optimum mass ratio of MoS 2 to Ti 3 C 2 T x (6:1) displayed the best MWA performance. The minimum reflection loss ( RL ) value of −41.5 dB was attained with a layer thickness of only 2.0 mm at 12.2 GHz and a 3.6 GHz maximum efficacious absorption bandwidth. The MWA mechanism of MoS 2 /Ti 3 C 2 T x composites was comprehended from multiple reflections and scattering effects, synergetic effects of conductive losses and attenuation capacity, and polarization relaxations. This work provides a facile method for the synthesis of 2D/2D heterostructure, and also provides a candidate material as potential microwave absorber.
危险品化学品经营许可证（带存储）