Design and fabrication of MoSe2/WO3 thin films for the construction of electrochromic devices on indium tin oxide based glass and flexible substrates

Electrochromic devices (ECDs) have the ability to block the heat generated by sunlight, making them ideal for use in smart windows. Herein, we report the fabrication of ECDs using MoSe₂/WO₃ (MSW) as the electrochromic material, for smart windows applications. A solvothermal method was used for the synthesis of MoSe₂, while WO₃ was synthesized using a sol-gel approach. Subsequently, MoSe₂/WO₃ (MSW) hybrids with different wt% of MoSe₂ (0.05 wt%, 0.2 wt%, 0.5 wt%) were synthesized using an ultra-sonication approach. The physicochemical features of these MSW hybrids herein termed as MSW 0.05, MSW 0.2 and MSW 0.5, were investigated using X-ray diffraction (XRD), X-ray photon electron spectroscopic (XPS), scanning electron microscope (SEM), and EDS techniques and compared with pristine MoSe₂ and WO₃. The ECDs synthesized using MSW 0.05 showed increased coloration efficiency (62 cm^2 C-1) with an applied potential range of 0 to −1.5 V. Subsequently, the ECDs based on indium tin oxide (ITO) and MSW 0.05 demonstrated excellent electrochromic performance and stability for 10,000 cycles. The enhanced electrochromic performance of the MSW-based ECDs may be attributed to the conductive nature as well as the synergistic effects between MoSe₂ and WO₃ when compared to the WO₃-based ECDs. The synthesized MSW also showed promise as an electrochromic material in flexible ECDs for smart windows applications.     

Nanomaterials Based on Polyanilines and MoSe2

Polyaniline, poly(N-methyl aniline), poly(2-ethyl aniline) and poly(2-propyl aniline) were intercalated into layered molybdenum diselenide by using the exfoliation/restacking property of Li_xMoSe₂. MoSe₂ was reacted with n-butyllithium to form Li_xMoSe₂. The Li_xMoSe₂ was exfoliated in N-methylformamide (NMF) with the help of ultrasonication which lead to the formation of single layers of MoSe₂. Addition of NMF solutions of the polymers to the exfoliated layers resulted in their intercalation into MoSe₂. The products were characterized by powder X-ray diffraction. Fourier transform infra-red spectroscopy, and four-probe van der Pauw technique electrical conductivity measurements are reported here for the first time.     

High photocatalytic and photoelectrochemical performance of a novel 0D/2D heterojunction photocatalyst constructed by ZnSe nanoparticles and MoSe2 nanoflowers

Metal oxide photocatalysts have the disadvantages of large band gap and high internal resistance, and their photoelectrochemical properties are restricted. Metal selenides are generally characterized by narrow bandgap width, low internal resistance, high utilization rate of sunlight and superior photoelectrochemical performance. The ZnSe/MoSe₂ heterostructure composite was successfully constructed by loading ZnSe nanoparticles onto MoSe₂ nanoplates with three-dimensional flower-like structure. In this heterostructure composite, ZnSe nanoparticles are uniformly encapsulated by MoSe₂ nanoplates, and the larger contact surface facilitates the transfer of carriers between heterojunction, while the three-dimensional flower structure of MoSe₂ can transport and collect photogenerated carriers. This heterojunction composite has a full-band absorption capability of UV and visible light. Photocatalytic tests showed that the photocatalytic activity of the heterojunction photocatalyst was more than twice of MoSe₂ and more than 4 times of ZnSe at the optimum ZnSe composite ratio, and photoelectric performance of that was 2.75 times of MoSe₂. The results show that the photoelectrochemical performance of ZnSe/MoSe₂ has been greatly improved, mainly because of the 0D/2D structure and band matching of ZnSe/MoSe₂, so that the photogenerated electrons excited on the ZnSe conduction band can be transported to the conduction band of MoSe₂, thereby improving the carriers’ separation efficiency and photoelectrochemical performance.     

Methanol oxidation at Pt/MoO x /MoSe2 thin film electrodes prepared with exfoliated MoSe2

This paper presents results on the dispersion of Pt on MoO _x /MoSe₂ electrodes, which were prepared by an intercalation–exfoliation technique. The Pt/MoO _x /MoSe₂ electrodes were tested for methanol oxidation by cyclic voltammetry. Thin films of MoSe₂ can be oxidized electrochemically to form a MoO _x layer. Compared with pure platinum, Pt/MoO _x /MoSe₂ electrodes gave lower oxidation potentials and higher current densities. We believe that methanol adsorption and subsequent dehydrogenation occur at the Pt atoms, while the OH_ads nucleation occurs at Mo sites. The presence of the adsorbed —OH groups on Mo sites may catalyze CO oxidation to CO₂. This surface reaction is necessary for the improved electrocatalytic behavior of Pt/MoO _x /MoSe₂ electrodes.     

Mixed 3D/2D dimensional TiO2 nanoflowers/MoSe2 nanosheets for enhanced photoelectrochemical hydrogen generation

Recently, v arious kinds of methods have been implemented to broaden the visible light response and fasten the carrier's separation of TiO₂-based photoanodes. As a promising hydrogen evolution reaction catalyst, MoSe₂ is rarely investigated especially combined with TiO₂ photoanode. In this study, we report a composite photoanode of MoSe₂ nanosheets (with 1T and 2H phase)-modified 3D TiO₂ nanoflowers (NFs).The hybrid of 3D TiO₂ NFs/2D MoSe₂ holds great promise in boosting the PEC water splitting performance. TiO₂ NFs/MoSe₂-15 showed the largest photocurrent density of 1.40 mA/cm², which was five times higher than that of pure TiO₂ NFs under AM1.5G illumination. Moreover 10 times improvement in current density was observed for the TiO₂ NFs/MoSe₂-15 under visible light. This increase could be ascribed to synergistic effects of light absorption enhancement and more efficient carrier separation after MoSe₂ modification. This study not only provides a reference to boost the photoelectrochemical performance of photoelectrodes but also renders a perspective on the potential applications of MoSe₂ nanosheets.     

A strategy of combination reaction to improve electrochemical performance in two-dimensional Mo1-xWxSe2 battery-type electrode materials

We report here a case of combination reaction between MoSe₂ and WSe₂ in certain proportions to improve electrochemical performance of Mo_1-xW_xSe₂ compound materials. Two-dimensional (2D) Mo_1-xW_xSe₂ flower-like crystals (x = 0, 0.25, 0.5, 0.75, 1) were synthesized using a solution synthesis method, and then Mo_1-xW_xSe₂-based electrodes were prepared using a powder pellet method. Their structure and electrochemical performance were respectively measured by X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectrometer (XPS), scanning electron microscope (SEM), and electrochemical workstation. The results indicate that only Mo_0.25W_0.75Se₂-based electrode (x = 0.75), compared with other electrodes, delivers excellent specific capacity and stability with the capacity retention of 74.4% after 5000 charging-discharging deep cycles at the current density of 2 A g^?1 in 1.0 mol/L KOH aqueous electrolyte, and exhibits a Coulombic efficiency almost 100% after 5000 cycles. This phenomenon is attributed to a situation that Mo_0.25W_0.75Se₂ active material has a quite different electronic band structure from the other remaining materials. It is therefore concluded that the combination reaction enables Mo_1-xW_xSe₂ composite materials to realize their potential in electrochemical energy storage.     

Modulation of MoSe2 & MnFe2O4@MnO2 nano-architectures for microwave absorption properties via single- and bilayer method

The electromagnetic pollution problem, particularly at microwave frequencies, poses a threat to not only sensitive technological gadgets but also to the health of humans. Therefore, there is a great need for lightweight and highly effective microwave-absorbing materials (MAMs). Here, we fabricated a hierarchical flower-like MoSe₂ structure and a rod-like MnFe₂O₄@MnO₂ architecture via a solvothermal method. Single-layer and bilayer samples were fabricated to study the microwave absorption feature. In single-layer samples, the flower-like MoSe₂ structure has better microwave absorption properties than the rod-like MnFe₂O₄@MnO₂ architecture. And in bilayer absorbing samples, a sample with a flower-like MoSe₂ structure as the top layer shows high absorption performance. Moreover, in bilayer samples, changes were made to the thickness of both layers to find the best parameters. An optimal bilayer sample has been achieved with a flower-like dielectric MoSe₂ structure as a top layer having a 1 mm thickness and magnetic MnFe₂O₄@MnO₂ as a bottom layer also with a 1 mm thickness; indicating that a strong absorption can only be attained by balancing dielectric loss and magnetic loss. Moreover, the optimal sample shows decent absorption with an effective absorption bandwidth (EAB) of 5.4 GHz (14.7–9.3 GHz) with a 1 mm thickness of each layer. The simulated results of the optimal sample have also been compared with experimental results. These results suggest a different approach for developing MAMs in the future.     

MoSe1.48S0.52@C as cathode material for rechargeable aluminum-ion batteries and Al–S batteries

Transition metal chalcogenides (TMDCs) present an excellent initial discharge capacity for aluminum ion batteries (AIBs). However, its strong acting force with Al³⁺ and poor electrical conductivity hinder the further application of TMDCs in high-capacity AIBs. In this work, Peony-like MoSe_1.48S_0.52@C was prepared for AIBs cathode by hydrothermal method. The outsourced carbon reduces the agglomeration of MoSe_1.48S_0.52. Meanwhile, the S doping to form Se_1.48S_0.52 interlayer ligands, together with the Se presence to lower the band gap, enhances electrons transport and storage performance of aluminum. In addition, the material MoSe_1.48S_0.52@C can stably accommodate S nanoparticles and anchor aluminum sulfide to enhance the electrochemical stability of the cathode. The electrochemical test result shows that the specific capacitance of MoSe_1.48S_0.52@C reaches 300.8 mAh g^?1 at 100 mA g^?1. Note that the specific capacity for MoSe_1.48S_0.52@C@S is up to 1000 mAh g^?1 at 200 mA g^?1.     

Synthesis and rheological characterization of nano-magnetorheological fluid using inverse spinel ferrite (NiFe2O4)

In recent years, the utilization of nanoparticles for nano-magnetorheological fluid (NMRF) synthesis is gaining popularity in automotive applications. From this perspective, the nickel ferrite (NiFe₂O₄) nanoparticles were prepared by gel burning method and characterized using the X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy-energy dispersive X-ray analysis (FESEM-EDX), and vibration sample magnetometer (VSM). The XRD and FTIR results showed the phase formation and characteristic metal–oxygen M–O vibrations. The FESEM images showed quasi-spherical crystallites with considerable agglomeration. The magnetic properties measured showed the ferromagnetic nature of NiFe₂O₄. The nanosized NiFe₂O₄ was used for NMRF preparation and characterization.     

Photocatalytic oxidative desulfurization of dibenzothiophene catalyzed by amorphous TiO2 in ionic liquid

Three types of TiO₂ were synthesized by a hydrolysis and calcination method. The catalysts were characterized by X-ray powder diffraction (XRD), diffuse reflectance spectrum (DRS), Raman spectra, and X-ray photoelectron spectroscopy (XPS). The XRD and Raman spectra indicated that amorphous TiO₂ was successfully obtained at 100 °C. The results indicated that amorphous TiO₂ achieved the highest efficiency of desulfurization. The photocatalytic oxidation of dibenzothiophene (DBT), benzothiophene (BT), 4,6-dimethyldibenzothiophene (4,6-DMDBT) and dodecanethiol (RSH) in model oil was studied at room temperature (30 °C) with three catalysts. The system contained amorphous TiO₂, H₂O₂, and [Bmim]BF₄ ionic liquid, ultraviolet (UV), which played vitally important roles in the photocatalytic oxidative desulfurization. Especially, the molar ratio of H₂O₂ and sulfur (O/S) was only 2: 1, which corresponded to the stoichiometric reaction. The sulfur removal of DBT-containing model oil with amorphous TiO₂ could reach 96.6%, which was apparently superior to a system with anatase TiO₂ (23.6%) or with anatase — rutile TiO₂ (18.2%). The system could be recycled seven times without a signicant decrease in photocatalytic activity.     

Growth of nanolaminate structure of tetragonal zirconia by pulsed laser deposition

Alumina/zirconia (Al₂O₃/ZrO₂) multilayer thin films were deposited on Si (100) substrates at an optimized oxygen partial pressure of 3 Pa at room temperature by pulsed laser deposition. The Al₂O₃/ZrO₂ multilayers of 10:10, 5:10, 5:5, and 4:4 nm with 40 bilayers were deposited alternately in order to stabilize a high-temperature phase of zirconia at room temperature. All these films were characterized by X-ray diffraction (XRD), cross-sectional transmission electron microscopy (XTEM), and atomic force microscopy. The XRD studies of all the multilayer films showed only a tetragonal structure of zirconia and amorphous alumina. The high-temperature XRD studies of a typical 5:5-nm film indicated the formation of tetragonal zirconia at room temperature and high thermal stability. It was found that the critical layer thickness of zirconia is ≤10 nm, below which tetragonal zirconia is formed at room temperature. The XTEM studies on the as-deposited (Al₂O₃/ZrO₂) 5:10-nm multilayer film showed distinct formation of multilayers with sharp interface and consists of mainly tetragonal phase and amorphous alumina, whereas the annealed film (5:10 nm) showed the inter-diffusion of layers at the interface.     

Experimental determination of the eutectic temperature in air of the CuO-TiO2 pseudobinary system

Eutectic temperature and composition in the CuO-TiO₂ pseudobinary system have been experimentally determined in air by means differential thermal analysis (DTA), thermogravimetry (TG) and hot-stage microscopy (HSM). Samples of the new eutectic composition treated at different temperatures have been characterized by X-ray diffraction (XRD) and X-ray absorption near-edge structural spectroscopy (XANES) to identify phases and to determine the Cu valence state, respectively. The results show that the eutectic temperature in air is higher by 100 °C (∼1000 °C) for a Ti-richer composition (XTiO₂=25 mol%) than the one calculated in the literature. The reduction of Cu²⁺ to Cu⁺ takes places at about 1030 °C. The existence of Cu₂TiO₃ and Cu₃TiO₄ has been confirmed by XRD in the temperature range between 1045 and 1200 °C.     

Effect of Ni Doping on the Structural and Optical Properties of TiO<Subscript>2</Subscript> Nanoparticles at Various Concentration and Temperature

TiO₂ nanopowders doped by Ni were prepared by sol–gel method. The effects of Ni ion (transition metal ion) doping on the physical structural and optical properties of TiO₂ have been investigated by X-ray diffraction (XRD), scanning electron microscopy and UV–Vis absorption spectroscopy. XRD results suggest that adding impurities has a significant effect on anatase phase stability, crystallinity, and particle size of TiO₂. The phase transformation from anatase to rutile was inhibited by Ni ion doped TiO₂ at temperatures 675 °C. The lowest band gap value (2.83 eV) was obtained for TiO₂-4%Ni sample calcined at 675 °C.     

Activity of Ni Substituted Ca-La-hexaaluminate Catalyst in Dry Reforming of Methane

Ca_1?x La _x NiAl₁₁O_19?δ(O ≤ x≤1) hexaaluminate oxydes were synthesized starting from nitrate salts of Ca, La, Ni and Al precipitated by citric acid. After calcination they were used as catalysts precursors in dry reforming of methane to synthesis gas at atmospheric pressure (600–800 °C) with a mixture of CH₄/CO₂/Ar:1/1/3. The solids were characterized by X-ray diffraction (XRD), BET surface area, temperature programmed reaction and oxidation (TPO) and by X-ray photoelectron spectroscopy. XRD analysis shows a pure hexaluminate phase as soon as a part of calcium has been substituted by lanthanum. After H₂ reduction and after reactivity test, Ni metal characterized by XRD is responsible of the high activity (equilibrium conversion near 100% at 800 °C). Ni hexaaluminate shows a remarkable high stability (more than 300 h test) probably due to the low formation of surface carbon (TPO).     

Structural and optical properties of ITO/TiO2 anti-reflective films for solar cell applications

Indium tin oxide (ITO) and titanium dioxide (TiO₂) anti-reflective coatings (ARCs) were deposited on a (100) P-type monocrystalline Si substrate by a radio-frequency (RF) magnetron sputtering. Polycrystalline ITO and anatase TiO₂ films were obtained at room temperature (RT). The thickness of ITO (60 to 64 nm) and TiO₂ (55 to 60 nm) films was optimized, considering the optical response in the 400- to 1,000-nm wavelength range. The deposited films were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and atomic force microscopy (AFM). The XRD analysis showed preferential orientation along (211) and (222) for ITO and (200) and (211) for TiO₂ films. The XRD analysis showed that crystalline ITO/TiO₂ films could be formed at RT. The crystallite strain measurements showed compressive strain for ITO and TiO₂ films. The measured average optical reflectance was about 12% and 10% for the ITO and TiO₂ ARCs, respectively.     

Ultrasonic-assisted preparation of AlON from alumina/carbon core-shell nanoparticle

An aluminium oxynitride (AlON) powder was synthesized by carbothermal reduction nitridation (CRN) method. For this purpose, first Al₂O₃/C core-shell nanoparticles were prepared by the pyrolysis of Al₂O₃/polyacrylonitrile (PAN) nanocomposite precursor at 800?°C for 2?h in an argon atmosphere. Alumina/PAN precursor was prepared by ultrasonic method at room temperature. Then, by two-step thermal treatment of Al₂O₃/C core-shell nanoparticles at 1500–1600?°C for 2?h, followed by subsequent heating at 1750?°C for 1?h in N₂ flow, AlON powder was synthesized. The sample was investigated via Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and CHNS elemental analysis.     

Synthesis and characterization of carbon-supported Pt–Ru–WOx catalysts by spectroscopic and diffraction methods

Carbon-supported Pt–Ru–WO _x /C catalysts for application in PEMFC anodes were synthesized by a modified Bönnemann method. Their electrocatalytic activity for the oxidation of H₂/CO mixtures and CH₃OH was measured by E/i-curves in PEM single cell arrangements under working conditions. Information about composition, microstructure and nanomorphology was obtained by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray fluorescence analysis (XFA) and transmission electron microscopy (TEM). X-ray diffraction data at room temperature show only one single Pt f.c.c. phase; no evidence of Ru, W and their oxides, respectively, is found. Hence, the presence of W and Ru as amorphous oxide species seems likely. Surface-sensitive XPS measurements detect Pt⁰, platinum oxide and hydroxide species, metallic Ru, ruthenium oxide, hydrous ruthenium oxide and WO₃. For the crystalline platinum phase particle sizes of less than 2 nm were determined by TEM images and XRD patterns via solving the Scherrer equation. Temperature-dependent XRD measurements were performed to show the influence of ageing on the catalyst structure.     

One-pot hydrothermal synthesis of MoS2 nanosheets/C hybrid microspheres

Uniform MoS₂ nanosheets/C hybrid microspheres with mean diameter of 320 nm have been successfully synthesized via a facile one-pot hydrothermal route by sodium molybdate reacting with sulfocarbamide in d-glucose solutions. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). XRD patterns showed that the MoS₂ was kept as a two-dimensional nanosheet crystal and C was retained as amorphous even after their annealing treatment at 800 °C. TEM and SEM images indicated that the MoS₂ nanosheets were uniformly dispersed in the amorphous carbon. The experiment results also revealed that the appropriate amount of d-glucose had an obvious effect on the formation of uniform MoS₂ nanosheets/C hybrid microspheres. A possible formation process of MoS₂ nanosheets/C hybrid microspheres was preliminarily presented.     

One Step Synthesis of NiO Nanoparticles via Solid-State Thermal Decomposition at Low-Temperature of Novel Aqua(2,9-dimethyl-1,10-phenanthroline)NiCl2 Complex

[NiCl₂(C₁₄H₁₂N₂)(H₂O)] complex has been synthesized from nickel chloride hexahydrate (NiCl₂·6H₂O) and 2,9-dimethyl-1,10-phenanthroline (dmphen) as N,N-bidentate ligand. The synthesized complex was characterized by elemental analysis, infrared (IR) spectroscopy, ultraviolet-visible (UV-vis) spectroscopy and differential thermal/thermogravimetric analysis (TG/DTA). The complex was further confirmed by single crystal X-ray diffraction (XRD) as triclinic with space group P-1. The desired complex, subjected to thermal decomposition at low temperature of 400 ºC in an open atmosphere, revealed a novel and facile synthesis of pure NiO nanoparticles with uniform spherical particle; the structure of the NiO nanoparticles product was elucidated on the basis of Fourier transform infrared (FT-IR), UV-vis spectroscopy, TG/DTA, XRD, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDXS) and transmission electron microscopy (TEM).     

Fabrication of SnO2 and SiO2 nanoparticle-embedded carbon nanofiber composites via co-electrospinning

Carbon nanofiber (CNF) composites composed of SnO₂ and SiO₂ nanoparticles in the CNF were fabricated via a co-electrospinning method, and the weight percentage ratio of the SnO₂ and SiO₂ nanoparticles to the CNF was controlled to investigate their morphology and structural properties. Their structural characteristics and chemical compositions were shown by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and bright-field transmission electron microscopy (TEM). The TEM energy-dispersive X-ray spectroscopy (EDS) mapping results showed that the SnO₂ and SiO₂ nanoparticles were well distributed in the CNF, implying the successful formation of CNF composites consisting of three types of phases.