Facile Water-Based Strategy for Synthesizing MoO3-x Nanosheets: Efficient Visible Light Photocatalysts for Dye Degradation

Unique CdS@MoS2 Core Shell Heterostructure for Efficient Hydrogen Generation Under Natural Sunlight

The hierarchical nanostructured CdS@MoS2 core shell was architectured using template free facile solvothermal technique. More significantly, the typical hexagonal phase of core CdS and shell MoS2 has been obtained. Optical study clearly shows the two steps absorption in the visible region having band gap of 2.4 eV for CdS and 1.77 eV for MoS2. The FESEM of CdS@MoS2 reveals the formation of CdS microsphere (as a core) assemled with 40-50 nm nanoparticles and covered with ultrathin nanosheets of MoS2 (Shell) having size 200-300 nm and the 10-20 nm in thickness. The overall size of the core shell structure is around 8 µm. Intially, there is a formation of CdS microsphre due to high affinity of Cd ions with sulfur and further growth of MoS2 thin sheets on the surface. Considering band gap ideally in visible region, photocatalytic hydrogen evolution using CdS@MoS2 core shell was investigated under natural sunlight. The utmost hydrogen evolution rate achieved for core shell is 416.4 µmole h-1 with apparent quantum yield 35.04%. The photocatalytic activity suggest that an intimate interface contact, extended visible light absorption and effective photo generated charge carrier separation contributed to the photocatalytic enhancement of the CdS@MoS2 core shell. Additional, the enhanced hole trapping process and effective electrons transfer from CdS to MoS2 in CdS@MoS2 core shell heterostructures can significantly contribute for photocatalytic activity. Such core shell heterostructure will also have potential in thin film solar cell and other microelectronic devices.

Two-Dimensional Cr-Doped MoO2.5(OH)0.5 Nanosheets: A Promising Anode Material for Lithium-Ion Batteries

α-MoO₃ has gained growing attention as an anode material of lithium-ion batteries (LIBs) because it has a high theoretical specific capacity of 1111 mA h g^-1 and unique layer structure. However, the electrochemical reactions of MoO₃ exhibit sluggish kinetics and structural instability caused by pulverization during charge and discharge. Herein, we report new two-dimensional Cr-doped MoO_2.5(OH)_0.5 (doped MoO_2.5(OH)_0.5) ultrathin nanosheets prepared by a facile hydrothermal process. The formation of the ultrathin nanosheets was clarified by a "doping-adsorption" model. Compared with doped MoO₃, doped MoO_2.5(OH)_0.5 has larger expanded spacing of the {0 l0} crystal planes for fast Li⁺ storage. The electrodes after cycling were investigated by ex situ transmission electron microscopy in combination with X-ray photoelectron spectroscopy analysis to reveal the reversible conversion reaction mechanism of doped MoO_2.5(OH)_0.5 nanosheets. Interestingly, for doped MoO_2.5(OH)_0.5 nanosheet electrodes, it was found that the as-formed intermediate Li _xMoO₃ nanodots were well-dispersed in the mesoporous amorphous matrix and had an expanded (040) crystal plane after 10 cycles. These unique structural features increased the effective surface of intermediate products Li _xMoO₃ to react with Li⁺ and shortened the diffusion length and thus promoted the electrochemical reactions of doped MoO_2.5(OH)_0.5. Additionally, the presence of Cr also played a critical role in the reversible decomposition of Li₂O and enhanced specific capacity. When employed as an anode in LIBs, doped MoO_2.5(OH)_0.5 nanosheets show superior reversible capacity (294 mA h g^-1 at 10 A g^-1 after 2000 cycles). Moreover, the reversible capacity after electrochemical activation is quite stable throughout the cycling, thereby presenting a potential candidate anode material for LIBs.

Molybdenum Trioxide: Efficient Nanosorbent for Removal of Methylene Blue Dye from Aqueous Solutions

Nano Molybdenum trioxide (α-MoO₃) was synthesized in an easy and efficient approach. The removal of methylene blue (MB) in aqueous solutions was studied using this material. The effects of various experimental parameters, for example contact time, pH, temperature and initial MB concentration on removal capacity were explored. The removal of MB was significantly affected by pH and temperature and higher values resulted in increase of removal capacity of MB. The removal efficiency of Methylene blue was 100% at pH = 11 for initial dye concentrations lower than 150 ppm, with a maximum removal capacity of 152 mg/g of MB as gathered from Langmuir model. By comparing the kinetic models (pseudo first-order, pseudo second-order and intraparticle diffusion model) at various conditions, it has been found that the pseudo second-order kinetic model correlates with the experimental data well. The thermodynamic study indicated that the removal was endothermic, spontaneous and favorable. The thermal regeneration studies indicated that the removal efficiency (99%) was maintained after four cycles of use. Fourier Transform Infrared (FTIR) and Scanning Electron Microscopy (SEM) confirmed the presence of the MB dye on the α-MoO₃ nanoparticles after adsorption and regeneration. The α-MoO₃ nanosorbent showed excellent removal efficiency before and after regeneration, suggesting that it can be used as a promising adsorbent for removing Methylene blue dye from wastewater.

Visible light induced degradation of pollutant dyes using a self-assembled graphene oxide–molybdenum oxo-bis(dithiolene) composite

An easily separable graphene oxide–molybdenum oxo-bis(dithiolene) ([Ph₄P]₂[MoO(S₂C₂(CN)₂)₂]) composite degraded Rhodamine B and Rose Bengal dye upon visible light exposure.