Electrochemical synthesis of ultrafast and gram-scale surfactant-free tellurium nanowires by gas-solid transformation and their applications as supercapacitor electrodes for p-doping of graphene transistors

Interfacial Tension-Impelled Self-Assembly and Morphology Tuning of Poly(3,4-ethylene dioxythiophene)/Tellurium Nanocomposites at Various Liquid/Liquid Interfaces

Compared to the enormous number of nanostructures that have been documented, the variety of nanostructures produced by organic polymerization is rather limited. We devised an unconventional route and a sustainable approach to distribute tellurium nanoparticles (Te NPs) in a poly(3,4-ethylene dioxythiophene) (PEDOT) matrix to form semiconducting organic-inorganic nanocomposites for potential applications in electrochemical sensing. The adopted strategy of in situ liquid/liquid interface-assisted polymerization aids in the formation of intimately tethered Te NPs on the PEDOT polymer chains, thereby preventing the aggregation of Te NPs. The untapped versatility inherent to using biphasic systems for interfacial polymerization is explored at three interface systems of immiscible solvents: chloroform/water, dichloromethane/water, and hexane/water, giving rise to PEDOT/Te nanocomposite (PTeNC) of distinct morphology. Chemical nature, crystallinity, and morphology investigations proved the successful formation of PTeNC in different interface systems. Consequently, the temporal evolution of interfacial tension in the preferential adsorption of nanoparticles and final product morphology was monitored by pendant drop tensiometry. Owing to the role of morphology, PTeNC synthesized at the hexane/water interface showcased the best electrocatalytic behavior toward nonenzymatic detection of l-ascorbic acid, an essential nutritional factor, and a neuromodulator with a limit of detection of 0.66 μM and excellent sensitivity, selectivity, and reproducibility. Hence, we envision that interface-assisted polymerization offers a nascent and robust strategy for encapsulating unusual electrode materials in polymeric matrices.

Reduced graphene oxide doped tellurium nanotubes for high performance supercapacitor

Supercapacitors have been achieving great interest in energy storage systems for the past couple of decades. Such devices with superior performance, mainly, depending on the material architecture of the electrodes. We report on the preparation of Tellurium nanotubes (Te-tubes diameter ∼100 nm and length ∼700 nm), with variable doping of conducting network reduced graphene oxide (rGO) to fabricate high-performance electrode characteristics of rGO @ Te. The prepared material was characterized using XRD, FTIR, FESEM, and Raman spectroscopy techniques, including Brunauer-Emmett-Teller, Barrett-Joyner-Halenda measurements. FTIR study revealed that 15% rGO @ Te has a wide C-O vibration band at ∼ 1,100–1,300 cm⁻¹, over other compositions. FESEM study shows the Te-tubes dispersion in rGO layers. The EDX study revealed that 15% of the composition has an optimistic concentration of C and O elements. In other compositions, either at lower/higher rGO concentration, an uneven count of C and O is observed. These support efficient charge dynamics to achieve superior ultra-capacitor characteristics, thereby achieving specific capacitance C_sp 170 + F/g @ 10 mV/s in a symmetric configuration. The reported values are thirty times higher than pristine Te-tubes (∼5 F/g). This finding suggests that rGO @ Te is a promising candidate for supercapacitor.

Molecular Main Group Metal Hydrides

This review serves to document advances in the synthesis, versatile bonding, and reactivity of molecular main group metal hydrides within Groups 1, 2, and 12-16. Particular attention will be given to the emerging use of said hydrides in the rapidly expanding field of Main Group element-mediated catalysis. While this review is comprehensive in nature, focus will be given to research appearing in the open literature since 2001.

Synthesis of Molybdenum Sulfide/Tellurium Hetero-Composite by a Simple One-Pot Hydrothermal Technique for High-Performance Supercapacitor Electrode Material

It is necessary to investigate effective energy storage devices that can fulfill the requirements of short-term and long-term durable energy outputs. Here, we report a simple one-pot hydrothermal technique through which to fabricate the MoS2/Te nanocomposite to be used as an effective electrode material for high-performance supercapacitors. Comprehensive characterization of the as-fabricated nanomaterial was performed using FESEM, HRTEM, XRD, FTIR, XPS, etc., as well as electrochemical characterizations. The electrochemical characterization of the as-fabricated nanocomposite electrode material showed a high specific capacitance of 402.53 F g-1 from a galvanostatic charge-discharge (GCD) profile conducted at 1 A g-1 current density. The electrode material also showed significant rate performance with high cyclic stability reaching up to 92.30% under 4000 cycles of galvanostatic charge-discharge profile at a current density of 10 A g-1. The highly encouraging results obtained using this simple synthetic approach demonstrate that the hetero-structured nanocomposite of MoS2/Te electrode material could serve as a promising composite to use in effective supercapacitors or energy storage devices.

Binder Free and Flexible Asymmetric Supercapacitor Exploiting Mn3O4 and MoS2 Nanoflakes on Carbon Fibers

Emerging technologies, such as portable electronics, have had a huge impact on societal norms, such as access to real time information. To perform these tasks, portable electronic devices need more and more accessories for the processing and dispensation of the data, resulting in higher demand for energy and power. To overcome this problem, a low cost high-performing flexible fiber shaped asymmetric supercapacitor was fabricated, exploiting 3D-spinel manganese oxide Mn₃O₄ as cathode and 2D molybdenum disulfide MoS₂ as anode. These asymmetric supercapacitors with stretched operating voltage window of 1.8 V exhibit high specific capacitance and energy density, good rate capability and cyclic stability after 3000 cycles, with a capacitance retention of more than 80%. This device has also shown an excellent bending stability at different bending conditions.

Reversible Electrochemical Phase Change in Monolayer to Bulk-like MoTe2 by Ionic Liquid Gating

Transition-metal dichalcogenides (TMDs) exist in various crystal structures with semiconducting, semi-metallic, and metallic properties. The dynamic control of these phases is of immediate interest for next-generation electronics such as phase change memories. Of the binary Mo and W-based TMDs, MoTe₂ is attractive for electronic applications because it has the lowest energy difference (40 meV) between the semiconducting (2H) and semi-metallic (1T') phases, allowing for MoTe₂ phase change by electrostatic doping. Here, we report phase change between the 2H and 1T' polymorphs of MoTe₂ in thicknesses ranging from the monolayer to bulk-like case (73 nm) using an ionic liquid electrolyte at room temperature and in air. We find consistent evidence of a partially reversible 2H-1T' transition using in situ Raman spectroscopy where the phase change occurs in the topmost layers of the MoTe₂ flake. We find a thickness-dependent transition voltage where higher voltages are necessary to drive the phase change for thicker flakes. We also show evidence of electrochemical activity during the gating process by observation of Te metal formation. This finding suggests the formation of Te vacancies which have been reported to lower the energy difference between the 2H and 1T' phases, potentially aiding the phase change process. Our discovery that the phase change can be achieved on the surface layer of bulk-like materials reveals that this electrochemical mechanism does not require isolation of a single layer and the effect may be more broadly applicable than previously thought.

Comparison of cytocompatibility and anticancer properties of traditional and green chemistry-synthesized tellurium nanowires

Background

Traditional physicochemical approaches for the synthesis of compounds, drugs, and nanostructures developed as potential solutions for antimicrobial resistance or against cancer treatment are, for the most part, facile and straightforward. Nevertheless, these approaches have several limitations, such as the use of toxic chemicals and production of toxic by-products with limited biocompatibility. Therefore, new methods are needed to address these limitations, and green chemistry offers a suitable and novel answer, with the safe and environmentally friendly design, manufacturing, and use of minimally toxic chemicals. Green chemistry approaches are especially useful for the generation of metallic nanoparticles or nanometric structures that can effectively and efficiently address health care concerns.

Objective

Here, tellurium (Te) nanowires were synthesized using a novel green chemistry approach, and their structures and cytocompatibility were evaluated.

Method

An easy and straightforward hydrothermal method was employed, and the Te nanowires were characterized using transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier-transform infrared spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, and optical microscopy for morphology, size, and chemistry. Cytotoxicity tests were performed with human dermal fibroblasts and human melanoma cells (to assess anticancer properties). The results showed that a treatment with Te nanowires at concentrations between 5 and 100 μg/mL improved the proliferation of healthy cells and decreased cancerous cell growth over a 5-day period. Most importantly, the green chemistry -synthesized Te nanowires outperformed those produced by traditional synthetic chemical methods.

Conclusion

This study suggests that green chemistry approaches for producing Te nanostructures may not only reduce adverse environmental effects resulting from traditional synthetic chemistry methods, but also be more effective in numerous health care applications.

Fabrication of Te and Te-Au Nanowires-Based Carbon Fiber Fabrics for Antibacterial Applications

Pathogenic bacteria that give rise to diseases every year remain a major health concern. In recent years, tellurium-based nanomaterials have been approved as new and efficient antibacterial agents. In this paper, we developed the approach to directly grow tellurium nanowires (Te NWs) onto commercial carbon fiber fabrics and demonstrated their antibacterial activity. Those Te NWs can serve as templates and reducing agents for gold nanoparticles (Au NPs) to deposit. Three different Te-Au NWs with varied concentration of Au NPs were synthesized and showed superior antibacterial activity and biocompability. These results indicate that the as-prepared carbon fiber fabrics with Te and Te-Au NWs can become antimicrobial clothing products in the near future.