• Energy Research

We designed 1T-MoS2/CNFs with different thicknesses of MoS2 layer, which affect conductivity, charge storage and transfer. Optimized 1T-MoS2/CNFs enhance supercapacitance and hydrogen evolution performance, offering a strategy for energy devices.

Bi2S3 has gained considerable attention as a semiconductor for its versatile functional properties, finding application across various fields, and liquid phase exfoliation (LPE) serves as a straightforward method to produce it in nano-form. Till now, the commonly used solvent for LPE has been N-Methyl-2-pyrrolidone, which is expensive, toxic and has a high boiling point. These limitations drive the search for more sustainable alternatives, with water being a promising option. Nonetheless, surfactants are necessary for LPE in water due to the hydrophobic nature of Bi2S3, and organic molecules with amphoteric characteristics are identified as suitable surfactants. However, systematic studies on the use of ionic surfactants in the LPE of Bi2S3 have remained scarce until now. In this work, we used sodium dodecyl sulfate (SDS), sodium dodecylbenzene sulfonate (SDBS) and sodium hexadecyl sulfonate (SHS) as representative species and we present a comprehensive investigation into their effects on the LPE of Bi2S3. Through characterizations of the resulting products, we find that all surfactants effectively exfoliate Bi2S3 into few-layer species. Notably, SDBS demonstrates superior stabilization of the 2D layers compared to the other surfactants, while SHS becomes the most promising surfactant for obtaining products with high yield. Moreover, the resulting nano-inks are used for fabricating films using spray-coating, reaching a fine tuning of band gap by controlling the number of cycles, and paving the way for the utilization of 2D Bi2S3 in optoelectronic devices.

Lightweight and flexible energy storage devices are gaining interest due to their potential integration into wearable electronics. They might work for the long-term powering of sensors, for example, but they need to be operative after the application of different types of mechanical stress. Conductive and semiconducting nanomaterials have been largely investigated as active components for this type of application but need to be coupled to an elastic matrix, such as a polymeric one, in order to be functional in flexible technologies. In this work, we investigate the production of electrospun nanofibers based on a ternary blend of 2D layered WS2, multiwalled carbon nanotubes, and carbon black in poly(ethylene oxide) and characterize their electrochemical behavior in symmetric supercapacitor architectures within bendable pouch cells, in conjunction with a robust analysis of the active materials’ mechanical properties. We find optimized specific capacitance values of up to 9 F g–1 after mechanical adjustment of the device and excellent capacitance retention after multiple bending cycles, revealing the potential of similar scaffolds for use in wearable energy storage devices to activate low-power electronics.

AbstractChemical surface functionalization of carbon nanodots (CNDs) offers a valuable opportunity to tailor multifunctionality in these nanocarbons, by engineering the composition of their molecular surface. Therefore, it is important to elucidate the type and amount of CNDs surface functionalization to be able to design their properties accurately. CNDs are often functionalized through amide coupling without validating the degree of surface functionalization. As a measure of surface functionalization, the amounts of primary amines via Kaiser test (KT) or imine reactions of the bare CNDs is often considered. However, this may lead to overestimating the degree of surface functionalization obtained by the pure amide coupling due to different reaction mechanisms and involved intermediates. Herein, four different CNDs prepared by microwave‐assisted synthesis from arginine or citric acid with varying amounts of ethylenediamine are presented. We resorted to combining physicochemical methods to provide elemental, structural, and optical information. By that, we developed a method to quantify the degree of surface functionalization by amide coupling and show that the surface functionalization is lower than anticipated. Comparing experimental optical features of the CNDs with different computed model systems enables us to provide a more advanced vision of structure‐property relationships in these still elusive nanocarbons.