Formation mechanism of Al2O3/MoS2 nanocomposite coating by plasma electrolytic oxidation(PEO)

In this study,an Al2O3/MoS2 nanocomposite coating was created on an aluminum 1050 substrate using the plasma electrolytic oxidation method.The zeta potential measurements showed that small MoS2 particles have negative potential and move toward the anode electrode.The nanoparticles of MoS2 were found to have a zeta potential of-25 mV,which prevents suspension in the solution.Thus,to produce an Al2O3/MoS2 nanocomposite,one has to use the microparticles of MoS2.The X-ray diffraction analyses showed that the produced coatings containedα-Al2O3,γ-Al2O3,and MoS2,and that the size of MoS2 particles can be reduced to 30 nm.It was observed that prolonged suspension in the electrolyte results in an enhanced formation of an Al2O3/MoS2 nanocomposite.Using the results,it was hypothesized that the mechanism of the formation of the Al2O3/MoS2 nanocomposite coating on the aluminum 1050 substrate is based on electrical energy discharge.

A New Insight in the Physical and Photoelectrochemical Properties of Molybdenum Disulfide Alpha-Hematite Nanocomposite Films

The alpha (α)-hematite (Fe2O3) as photoanode has been used for photoelectrochemical applications due to low bandgap, low cost, high chemical stability, nontoxicity, and abundance in nature. The doping with various transition metals, formation of nanostructured and nanocomposite of α-Fe2O3 have been attempted to enrich the carrier mobility, surface kinetics and carrier diffusion properties. The manuscript is an attempt to improve the photoelectrochemical properties of α-Fe2O3 by formation of nanocomposite with dichalcogenide (molybdenum disulfide (MoS2) nanomaterials. The nanocomposite of MoS2-α-Fe2O3 have been synthesized by varying the amount of MoS2 in sol-gel synthesis process. The nanocomposite MoS2-α-Fe2O3 materials were characterized using UV-visible, FTIR, SEM, X-ray diffraction, Raman and particle analyzer. The photoelectrochemical properties were investigated using cyclic voltammetry and chronoamperometry studies. The optical and structural properties of MoS2-α-Fe2O3 nanocomposite have been found to be dependent on MoS2 doping. The band gap has shifted whereas;the structure is more prominent as flower-like morphology, which is a result of doping of MoS2. The photocurrent is more pronounced with and without light exposition to MoS2-α-Fe2O3 based electrode in photoelectrochemical cell. We have understood the photoelectrochemical water splitting using nanocomposite α-Fe2O3-MoS2 through schematic representation based on experimental results. The enhanced photoelectrochemical properties of nanocomposite α-Fe2O3-MoS2 films have been observed as compared to pristine α-Fe2O3 and transition metal doped α-Fe2O3 nanostructured films.

Improved photocatalytic degradation of organic dye using Ag3PO4/MoS2 nanocomposite

Highly efficient Ag3PO4/MoS2 nanocomposite photocatalyst was synthe- sized using a wet chemical route with a low weight percentage of highly exfoliated MoS2 （0.1 wt.%） and monodispersed Ag3PO4 nanoparticles （-5.4 nm）. The structural and optical properties of the nanocomposite were studied using various characterization techniques, such as XRD, TEM, Raman and absorption spectroscopy. The composite exhibits markedly enhanced photocatalytic activity with a low lamp power （60 W）. Using this composite, a high kinetic rate constant （k） value of 0.244 min^-1 was found. It was observed that -97.6% of dye degrade over the surface of nanocomposite catalyst within 15 min of illumination. The improved photocatalytic activity of Ag3PO4/MoS2 nanocomposite is attributed to the efficient interfacial charge separation, which was supported by the PL results. Large surface area of MoS2 nanosheets incorporated with well dispersed Ag3PO4 nanoparticles further increases charge separation, contributing to enhanced degradation efficiency. A possible mechanism for charge separation is also discussed.

Mechanically exfoliated MoS_(2) nanosheets decorated with SnS_(2) nanoparticles for high-stability gas sensors at room temperature

Due to its unique physical,chemical and surface electronic properties,molybdenum disulfide(MoS_(2))nanosheets open up a new avenue for nitrogen dioxide(NO2)detection at room temperature.Nevertheless,the gas sensing properties of pure MoS_(2) nanosheets are inevitably degenerated by the adsorption of atmospheric oxygen,which results in weak stability for MoS_(2)-based gas sensors.Reducing surface defects and constructing heterojunctions may be effective strategies to improve the gas sensing properties of MoS_(2) nanosheets.In this work,we design a novel nanocomposite based on MoS_(2) nanosheets decorated with tin disulfide(SnS_(2))nanoparticles(MoS_(2)/SnS_(2))via combining the mechanical exfoliation method with the facile hydrothermal method.The experimental results indicate that,after surfaces decoration with SnS_(2) nanoparticles,the as-prepared gas sensor based on MoS_(2)/SnS_(2) nanocomposites exhibits reliable long-term stability with the maximum response value drift of less than 3%at room temperature.Moreover,the MoS_(2)/SnS_(2) sensor also possesses desirable gas sensing properties upon NO_(2) at room temperature,such as high sensitivity,rapid response/recovery speed(28 s/3 s,5×10^(-6) NO_(2)),satisfactory selectivity,favorable repeatability and reversibility.The improved gas sensing properties of MoS_(2)/SnS_(2) nanocomposites can be attributed to the unique electronic properties of MoS 2 nanosheets with the fewer layers structure and the competitive adsorption effect of SnS_(2) nanoparticles.This work elucidates that SnS_(2) nanoparticles serving as an effective antioxidative decoration can promote the stability of MoS_(2) nanosheets,providing a promising approach to achieve high-stability NO2 gas sensors at room temperature.