Various embodiments may relate to an optical device. The optical device may include a stacked structure having a first surface and a second surface opposite the first surface. The stacked structure may include a plurality of holes or grooves extending from the first surface towards the second surface. The stacked structure may include a transition metal dichalcogenide material (TMDC) material. A thickness of the stacked structure may be of any value less than 100 nm.

The present disclosure belongs to the technical field of wave absorbing materials, and discloses a one-dimensional coralloid NiS/Ni.sub.3S.sub.4@PPy@MoS.sub.2-based wave absorber, and a preparation method and use thereof. A preparation method of a one-dimensional coralloid NiS/Ni.sub.3S.sub.4@PPy@MoS.sub.2-based wave absorber includes the following steps. Preparing one-dimensional Ni nanowires by a reduction method. Coating a layer of polypyrrole (PPy) on the Ni nanowires by an in-situ polymerization method using pyrrole as a monomer, to obtain Ni@PPy nanowires. Coating MoS.sub.2 nanorods on the Ni@PPy nanowires by a hydrothermal synthesis method. Meanwhile, Ni as a sacrificial template is vulcanized into NiS/Ni.sub.3S.sub.4 to prepare the one-dimensional coralloid NiS/Ni.sub.3S.sub.4@PPy@MoS.sub.2-based wave absorber. The wave absorber has a novel surface morphology and simple preparation process.

A lubricant additive may be synthesized by forming a nanohybrid of a transition metal dichalcogenide and a metal borate, forming a base oil, and then dispersing the transition metal dichalcogenide into the base oil. An exemplary nanohybrid may be synthesized by forming a first solution by adding a borax solution to an aqueous solution of a metal source, forming a second solution by adding ethanol to the first solution, forming a mixture by mixing the transition metal dichalcogenide with the second solution, and heating the mixture at a temperature of 180° C. to 230° C. and a pressure of 5 to 20 bar under a nitrogen atmosphere.

A lubricant additive may be synthesized by forming a nanohybrid of a transition metal dichalcogenide and a metal borate, forming a base oil, and then dispersing the transition metal dichalcogenide into the base oil. An exemplary nanohybrid may be synthesized by forming a first solution by adding a borax solution to an aqueous solution of a metal source, forming a second solution by adding ethanol to the first solution, forming a mixture by mixing the transition metal dichalcogenide with the second solution, and heating the mixture at a temperature of 180° C. to 230° C. and a pressure of 5 to 20 bar under a nitrogen atmosphere.

A method for controlling the optical properties of a material comprises the steps of (1) applying a dopant to an undoped TMD film by solution dip-coating the TMD, wherein the solution is a dopant solution consisting of one of NADH (nicotinamide adenine dinucleotide) and TCNQ (7,7,8,8-tetracyanoquinodimethane), wherein the doped TMD film exhibits an altered refractive index (n) and extinction coefficient (k) in comparison to the undoped TMD film. The dopant solution is a 0.1M solution of NADH in anhydrous acetonitrile or a 0.1M solution of TCNQ in anhydrous methanol. Rinsing the doped TMD film with a solvent consisting of one of anhydrous acetonitrile and anhydrous methanol to create an undoped TMD film exhibiting a refractive index (n) and extinction coefficient (k) substantially similar to the original undoped TMD film. The TMD is selected from the group consisting of MoS.sub.2, MoSe.sub.2, WS.sub.2, WSe.sub.2, and TiS.sub.2.

A method for controlling the optical properties of a material comprises the steps of (1) applying a dopant to an undoped TMD film by solution dip-coating the TMD, wherein the solution is a dopant solution consisting of one of NADH (nicotinamide adenine dinucleotide) and TCNQ (7,7,8,8-tetracyanoquinodimethane), wherein the doped TMD film exhibits an altered refractive index (n) and extinction coefficient (k) in comparison to the undoped TMD film. The dopant solution is a 0.1M solution of NADH in anhydrous acetonitrile or a 0.1M solution of TCNQ in anhydrous methanol. Rinsing the doped TMD film with a solvent consisting of one of anhydrous acetonitrile and anhydrous methanol to create an undoped TMD film exhibiting a refractive index (n) and extinction coefficient (k) substantially similar to the original undoped TMD film. The TMD is selected from the group consisting of MoS.sub.2, MoSe.sub.2, WS.sub.2, WSe.sub.2, and TiS.sub.2.

Methods of synthesizing transition metal dichalcogenide nanoparticles include forming a metal-amine complex, combining the metal-amine complex with a chalcogen source in at least one solvent to form a solution, heating the solution to a first temperature for a first period of time, and heating the solution to a second temperature that is higher than the first temperature for a second period of time.

Methods of synthesizing transition metal dichalcogenide nanoparticles include forming a metal-amine complex, combining the metal-amine complex with a chalcogen source in at least one solvent to form a solution, heating the solution to a first temperature for a first period of time, and heating the solution to a second temperature that is higher than the first temperature for a second period of time.

A method embodiment involves preparing single metal or mixed transition metal chalcogenide using exfoliation of two or more different bulk transition metal dichalcogenides in a manner to form an intermediate hetero-layered transition metal chalcogenide structure, which can be treated to provide a single-phase transition metal chalcogenide.

A method embodiment involves preparing single metal or mixed transition metal chalcogenide using exfoliation of two or more different bulk transition metal dichalcogenides in a manner to form an intermediate hetero-layered transition metal chalcogenide structure, which can be treated to provide a single-phase transition metal chalcogenide.