Ion-beam-assisted fabrication and manipulation of metallic nanowires

Metallic nanowires (NWs) are the key performers for future micro/nanodevices. The controlled manoeuvring and integration of such nanoscale entities are essential requirements. Presented is a discussion of a fabrication approach that combines chemical etching and ion beam milling to fabricate metallic NWs. The shape modification of the metallic NWs using ion beam irradiation (bending towards the ion beam side) is investigated. The bending effect of the NWs is observed to be instantaneous and permanent. The ion beam-assisted shape manoeuvre of the metallic structures is studied in the light of ion-induced vacancy formation and reconfiguration of the damaged layers. The manipulation method can be used for fabricating structures of desired shapes and aligning structures at a large scale. The controlled bending method of the metallic NWs also provides an understanding of the strain formation process in nanoscale metals

One-step chemically vapor deposited hybrid 1T-MoS2/2H-MoS2 heterostructures towards methylene blue photodegradation

International audienceThe photocatalytic degradation of methylene blue is a straightforward and cost-effective solution for water decontamination. Although many materials have been reported so far for this purpose, the proposed solutions inflicted high fabrication costs and low efficiencies. Here, we report on the synthesis of tetragonal (1T) and hexagonal (2H) mixed molybdenum disulfide (MoS2) heterostructures for an improved photocatalytic degradation efficiency by means of a single-step chemical vapor deposition (CVD) technique. We demonstrate that the 1T-MoS2/2H-MoS2 heterostructures exhibited a narrow bandgap ∼ 1.7 eV, and a very low reflectance (<5%) under visible-light, owing to their particular vertical micro-flower-like structure. We exfoliated the CVD-synthesised 1T-MoS2/2H-MoS2 films to assess their photodegradation properties towards the standard methylene blue dye. Our results showed that the photo-degradation rate-constant of the 1T-MoS2/2H-MoS2 heterostructures is much greater under UV excitation (i.e., 12.5 × 10-3 min-1) than under visible light illumination (i.e., 9.2 × 10-3 min-1). Our findings suggested that the intermixing of the conductive 1T-MoS2 with the semi-conducting 2H-MoS2 phases favors the photogeneration of electron-hole pairs. More importantly, it promotes a higher efficient charge transfer, which accelerates the methylene blue photodegradation process

Fabrication control of MoS₂/MoO₂ nanocomposite via chemical vapor deposition for optoelectronic applications

International audienceWe report on the fabrication and control of MoS2/MoO2 nanocomposites exhibiting various optoelectronic properties. We demonstrate the growth of various compositions, shapes and crystalline structures by chemical vapor deposition (CVD). Microplates 1 to 30 µm to highly crystalline nanowires ∼ 100 nm in diam. are obtained. Our findings show that depending on the MoO2 content the band gap varies from 2 eV to 2.4 eV, whereas nanowires sample exhibits the lowest reflectance ≤ 10 % for λ ≥ 450 nm. Furthermore, the photoelectric properties of the produced samples were characterized by integrating them into photoconductive devices. Our results demonstrate a good photoresponse achieving 2 × 104 %, a responsivity as high as 1.13 mA/W, and a specific detectivity of 2.6 × 109 Jones for the nanowires, with a relatively rapid rise and decay times 1.6 s and 0.8 s, respectively. This work emphasizes the high potential of MoS2/MoO2 nanocomposite for the development of highly responsive optoelectronic devices