MoS2-2xSe2x Nanosheets Grown on Hollow Carbon Spheres for Enhanced Electrochemical Activity

Fe, P co-doped hybrid electrocatalyst for synergistic enhancement of electrocatalytic hydrogen evolution reaction durability performance

Defect engineering has been widely applied to improve the hydrogen evolution reaction (HER) performance of MoS2. In this work, a co-doped electrocatalyst on carbon fiber paper (CFP) for HER was prepared by coupling with simple hydrothermal and gas-phase phosphorylation process to improve the durability of the catalyst while enhancing the electrocatalytic performance (Fe-P-MoS2/CFP). The results showed that the overpotential at a current density of 10 mA cm-2 (η10) of Fe-P-MoS2/CFP was only 130 mV, which was much lower than those of other undoped and single-metal atom doping electrocatalysts. Electronic interactions between Fe, P and MoS2 reduced the local electron densities and changed the electronic structure of Mo and S, leading to the generation of additional p orbitals in the S site, thus optimizing the adsorption-desorption energy of hydrogen in the S site. In addition, compared to Fe-MoS2/CFP, Fe-P-MoS2/CFP showed better electrocatalytic durability in acidic conditions. The co-doping technique proposed within this study stands to offer a novel approach for amplifying the catalytic activity and stability of electrocatalysts.

Cysteine-Induced Chirality Evolution of Molybdenum Disulfide Nanodots from a Bottom-Up Strategy

The transfer of chirality from molecules to synthesized nanomaterials has recently attracted significant attention. Although most studies have focused on graphene and plasmonic metal nanostructures, layered transition metal dichalcogenides (TMDs), particularly MoS2, have recently garnered considerable attention due to their semiconducting and electrocatalytic characteristics. Herein, we report a new approach for the synthesis of chiral molybdenum sulfide nanomaterials based on a bottom-up synthesis method in the presence of chiral cysteine enantiomers. In the synthesis process, molybdenum trioxide and sodium hydrosulfide serve as molybdenum and sulfur sources, respectively. In addition, ascorbic acid acts as a reducing agent, resulting in the formation of zero-dimensional MoS2 nanodots. Moreover, the addition of cysteine enantiomers to the growth solutions contributes to the chirality evolution of the MoS2 nanostructures. The chirality is attributed to the cysteine enantiomer-induced preferential folding of the MoS2 planes. The growth mechanism and chiral structure of the nanomaterials are confirmed through a series of characterization techniques. This work combines chirality with the bottom-up synthesis of MoS2 nanodots, thereby expanding the synthetic methods for chiral nanomaterials. This simple synthesis approach provides new insights for the construction of other chiral TMD nanomaterials with emerging structures and properties. More significantly, the as-formed MoS2 nanodots exhibited highly defect-rich structures and chiroptical performance, thereby inspiring a high potential for emerging optical and electronic applications.

Chemical Vapor Deposition Growth of MoS2 on g-C3N4 Nanosheets for Efficient Removal of Tetracycline Hydrochloride

MoS₂ was vertically grown on g-C₃N₄ nanosheets by chemical vapor deposition to prepare nanocomposites named MS-CN samples. Because of a large-surface area of 545.2 m²·g^-1 and a total pore volume of 1.7 cm³·g^-1, the sample MS-CN revealed fast and large adsorption capacity for tetracycline hydrochloride (TCH). The adsorption kinetics model proved that TCH could be rapidly adsorbed within 5 min, and chemical adsorption was dominant. For single-component adsorption of TCH, the maximum adsorption capacity was ∼154 mg/g. The monolayer adsorption was carried out on the surface of MS-CN. Both of the film and intra-particle diffusion were considered as significant processes to facilitate adsorption. Thermodynamic parameters indicate that the adsorption of TCH is a spontaneous endothermic process. The adsorption of TCH was highly pH-dependent. The maximum adsorption capacity of TCH was obtained in the case of pH ∼ 7. After four adsorption and desorption cycles, MS-CN still maintained well-adsorption performance. Multiple adsorption mechanism, pore filling, electrostatic force, π-π conjugation, and hydrogen bonding interactions were studied. Because of fast adsorption, large adsorption capacity, and high stability, it is a promising adsorbent for antibiotics.

Nanohybridization of CoS2 /MoS2 Heterostructure with Polyoxometalate on Functionalized Reduced Graphene Oxide for High-Performance LIBs

To address the poor cycling stability and low rate capability of MoS₂ as electrode materials for lithium-ion batteries (LIBs), herein, the CoS₂ /MoS₂ /PDDA-rGO/PMo₁₂ nanocomposites are constructed via a simple hydrothermal process, combining the advantages of all three, namely, CoS₂ /MoS₂ heterojunction and polyoxometalates (POMs) provide abundant catalytically active sites and increase the multi-electron transfer ability, and the positively charged poly(diallyldimethylammonium chloride) modified reduced graphene oxide (PDDA-rGO) improve electronic conductivity and effectively prevent the aggregation of MoS₂ , meanwhile stabilize the negatively charged [PMo₁₂ O₄₀ ]^3- . After the electrochemical testing, the resulting CoS₂ /MoS₂ /PDDA-rGO/PMo₁₂ nanocomposite achieved 1055 mA h g^-1 initial specific capacities and stabilized at 740 mA h g^-1 after 150 cycles at 100 mA g^-1 current density. And the specific capacities of MoS₂ , MoS₂ /PDDA-rGO, CoS₂ /MoS₂ , and CoS₂ /MoS₂ /PDDA-rGO were 201, 421, 518, and 589 at 100 mA g^-1 after 150 cycles, respectively. The fact of the greatly improving capacity of MoS₂ -based nanocomposites suggests its potential for high performance electrode materials of LIBs. Moreover, the lithium storage mechanism of CoS₂ /MoS₂ /PDDA-rGO/PMo₁₂ has been discussed on the basis of cyclic voltammetry with different scan rates.

Edge Rich Ultrathin Layered MoS2 Nanostructures for Superior Visible Light Photocatalytic Activity

Nanostructures of layered 2D materials have been proven one of the significant recent trends for visible-light-driven photocatalysis because of their unique morphology, effective optical adsorption, and rich active sites. Herein, we synthesized ultrathin-layered MoS₂ nanoflowers and nanosheets with rich active sites by using a facile hydrothermal technique. The photocatalytic performance of the as-synthesized MoS₂ nanoflowers (NF) and nanosheets (NS) were investigated for the photodegradation of MB (methylene blue), MG (malachite Green), and RhB (rhodamine B) dye under visible light irradiations. Ultrathin-layered nanoflowers showed faster degradation (96% in 150 min) in RhB under visible light irradiation, probably due to a large number of active sites and high available surface area. The kinetic study demonstrated that the first-order kinetic model best explained the process of photodegradation. The MoS₂ nanoflowers catalysts has similar catalytic performance after four consecutive cyclic performances, demonstrating their good stability. The results showed that the MoS₂ nanoflowers have outstanding visible-light-driven photocatalytic activity and could be an effective catalyst for industrial wastewater treatment.