Adsorption Behavior of NO and NO2 on Two-Dimensional As, Sb, and Bi Materials: First-Principles Insights.

To address the most significant environmental challenges, the quest for high-performance gas sensing materials is crucial. Among numerous two-dimensional materials, this study investigates the gas-sensitive capabilities of monolayer As, Sb, and Bi materials. To compare the gas detection abilities of these three materials, we employ first-principles calculations to comprehensively study the adsorption behavior of NO and NO2 gas molecules on the material surfaces. The results indicate that monolayer Bi material exhibits reasonable adsorption distances, substantial adsorption energies, and significant charge transfer for both NO and NO2 gases. Therefore, among the materials studied, it demonstrates the best gas detection capability. Furthermore, monolayer As and Sb materials exhibit remarkably high capacities for adsorbing NO and NO2 gas molecules, firmly interacting with the gas molecules. Gas adsorption induces changes in the material's work function, suggesting the potential application of these two materials as catalysts.

Pollution-free interface of 2D-MoS2/1D-CuO vdWs heterojunction for high-performance photodetector.

Van der Waals heterostructures provide a new opportunity for constructing new structures and improving the performance of electronic and optoelectronic devices. However, the existing methods of constructing heterojunctions are still faced with problems such as impurity introduction, or complex preparation process and limited scope of application. Herein, a physisorption method is proposed to composite CuO nanorods on the surface of MoS2nanosheets. CuO nanorods and MoS2form type-Ⅱ heterojunctions, which promotes the separation and transport of photo-generated charge carriers. More importantly, compared with the transfer and coating methods, the physical adsorption method avoids the introduction of auxiliary materials during the whole process of constructing the heterojunction, and therefore effectively reduces the damage and pollution at the interface. The optimized MoS2/CuO heterojunction photodetector achieves a high photoresponsivity of ∼680.1 A W-1and a fast response speed of ∼29µs. The results demonstrate that the physisorption method provides a feasible approach to realize high performance photodetectors with pollution-free interfaces, and it can also be extended to the development of other low-dimensional hybrid heterojunction electronic and optoelectronic devices.

Strain engineering of lateral heterostructures based on group-V enes (As, Sb, Bi) for infrared optoelectronic applications calculated by first principles.

In this work, the electronic structure, and optical properties of As/Sb and Sb/Bi lateral heterostructures (LHS) along armchair and zigzag interfaces affected by strain were investigated by density functional theory. The LHSs presented strain-dependent band transformation characteristics and sensitivity features. And a reduction and transition of the bandgap was observed when the As/Sb and Sb/Bi LHS existed under compressive strain. The density of states and the conduction band minimum-valence band maximum characteristics exhibited corresponding changes under the strain. Then a spatial charge-separation phenomenon and strong optical absorption properties in the mid-infrared range can also be observed from calculated results. Theoretical research into As/Sb and Sb/Bi LHSs has laid a solid foundation for As/Sb and Sb/Bi LHS device manufacture.

Superparamagnetic MoS2@Fe3O4 nanoflowers for rapid resonance-Raman scattering biodetection.

Sensors for rapid and reliable detection of biomolecules are crucial for clinical medical diagnoses. Here, a rapid, ultra-sensitive, magnetic-assisted biosensor based on resonance Raman scattering at MoS2@Fe3O4 composite nanoflowers is presented. Raman shifts and X-ray photoelectron spectra indicated that the composite was formed via Fe-S covalent bonds. Convenient magnetic separations could be performed because of the superparamagnetic Fe3O4 nanoparticles. MoS2 E12g and A1g Raman peaks were used as probe signals for anti-interference immunoassays. The probe unit of the immunoassay also included goat anti-human IgG molecules that were used as the target analyte. Au substrates coupled with the goat anti-human IgG were used as capture units to form sandwich biosensors. Because of the magnetic enrichment, the detection limit was improved by three orders-of-magnitude and the detection time was reduced from 1.5 h to 1 min. Sandwich biosensors using MoS2@Fe3O4 nanoflowers as Raman probes could be very promising sensors for proteins, antigens, and other immunogenic biopolymers, as well as for corpuscular viruses and cells.

High-Response, Ultrafast-Speed, and Self-Powered Photodetection Achieved in InP@ZnS-MoS2 Phototransistors with Interdigitated Pt Electrodes.

Various hybrid zero-dimensional/two-dimensional (0D/2D) systems have been developed to fabricate phototransistors with better performance compared to two-dimensional (2D) layered materials as well as broaden potential applications. Herein, we integrated environment-friendly InP@ZnS core-shell QDs with high efficiency of light absorption and light-emitting properties with bilayer MoS2 for the realization of 0D/2D mixed-dimensional phototransistors. Interdigitated (IDT) electrodes with Pt-patterned arrays, acting as light collectors as well as plasmonic resonators, can further enhance light harvesting from the InP@ZnS-MoS2 hybrid phototransistors, contributing to achieving a photoresponsivity as high as 1374 A·W-1. Moreover, thanks to the asymmetric Pt/MoS2 Schottky junction at the source/drain contact, a self-powered characteristic with an ultrafast speed of 21.5 µs was achieved, which is among the best performances for 2D layered material-based phototransistors. In terms of these features, we demonstrated the artificial synapse network with short-time plasticity based on the self-powered photodetection device. Our work reveals the great potential of 0D/2D hybrid phototransistors for high-response, ultrafast-speed, and self-powered photodetectors coupled with artificial neuromorphic function.