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Abstract Salinity gradient energy (SGE), known as blue energy is harvested from mixing seawater with river water in a controlled way using ion exchange membranes (IEMs). Using 2D materials as IEMs improves the output power density from a few Wm−2 to a few thousands of Wm−2 over conventional membranes. In this review, we survey the efforts taken to employ the different 2D materials as nanoporous or lamellar membranes for SGE and provide a comprehensive analysis of the fundamental principles behind the SGE. Overall, this review is anticipated to explain how the 2D materials can make SGE a viable source of energy.

Abstract Light-emitting diodes (LEDs) are an indispensable part of our daily life. After being studied for a few decades, this field still has some room for improvement. In this regard, perovskite materials may take the leading role. In recent years, LEDs have become a most explored topic, owing to their various applications in photodetectors, solar cells, lasers, and so on. Noticeably, they exhibit significant characteristics in developing LEDs. The luminous efficiency of LEDs can be significantly enhanced by the combination of a poor illumination LED with low-dimensional perovskite. In 2014, the first perovskite-based LED was illuminated at room temperature. Furthermore, two-dimensional (2D) perovskites have enriched this field because of their optical and electronic properties and comparatively high stability in ambient conditions. Recent and relevant advancements in LEDs using low-dimensional perovskites including zero-dimensional to three-dimensional materials is reported. The major focus of this article is based on the 2D perovskites and their heterostructures (i.e., a combination of 2D perovskites with transition metal dichalcogenides, graphene, and hexagonal boron nitride). In comparison to 2D perovskites, heterostructures exhibit more potential for application in LEDs. State-of-the-art perovskite-based LEDs, current challenges, and prospects are also discussed. Graphical Abstract

Binary transition metal dichalcogenides (BTMDs) have attracted a lot of researchers to exploit their unique properties for different applications in various fields, mainly in energy and environment. Surprisingly, there are no attempts of utilizing BTMDs materials particularly nickel molybdenum selenide (NiMoSe2) as a catalyst support for organic transformations. Reusable catalysts are better alternatives to the transition metal‐free protocols for the synthesis of heterocyclic compounds. Herein, we report a NiMoSe2 BTMD catalyst with Lewis acidic (transition metal) and strongly basic (selenide) sites for the regioselective synthesis of 2,3,5‐tri(het)aryl‐pyrroles from β‐thioxoketone precursors. The present method is capable of giving the expected products in good to excellent yields (up to 80%). Different substituents like ester, cyano, alkyl, trifluoromethyl, methoxy, and halogens have shown tolerance under optimized reaction conditions. The recyclability and reusability of the catalyst was checked for five catalytic cycles without notable loss in reactivity. [ABSTRACT FROM AUTHOR]

2D transition metal dichalcogenide alloys are considered as the promising duo for energy storage and catalyst for light‐driven energy conversion applications due to their novel physicochemical properties. However, heterostructuring with other 2D materials is an effective strategy to enhance the charge storage kinetics as well as comprehensive spectral light response and efficient charge separation. Herein, Molybdenum sulfo selenide (MoSSe)/black phosphorous (BP) heterostructure is synthesized by a one‐pot solvothermal technique, and energy storage and conversion efficiency are characterized. Interestingly, the fabricated symmetric supercapacitor based on the MoSSe/BP hybrid shows an exceptional capacitance of 230 mF cm−2 with an excellent energy density of 31.9 µWh cm−2 and a power density of 805.7 µW cm−2. To validate the experimental findings, Density Functional Theory (DFT) computational simulations are carried out concurrently. The lower diffusion energy barrier for electrolytic ions, in the case of hybrid MoSSe/BP compared to pristine MoSSe, supports the higher charge storage performance. Finally, MoSSe/BP nanocomposites' photocatalytic hydrogen evolution reaction (HER) performance is evaluated under 400 W of UV–vis light, with eosin Y dye acting as a sensitizer and triethanolamine acting as a sacrificial agent. The MoSSe/BP nanocomposite exhibits the maximum photocatalytic HER activity of 5718 µmol h−1 g−1, greater than the bare MoSSe nanostructure. [ABSTRACT FROM AUTHOR]

Layered double hydroxides (LDHs) are well established inorganic nanomaterials. They are of researcher's interest due to their anion-exchange capability, high surface-to-volume ratio, enhanced basicity due to hydroxyl anions and lewis acidity due to different metal ions present in the lattice. Their compatibility with environmental friendly solvents like water and alcohol have attracted synthetic chemists to develop green protocol in organic catalysis reactions. Interestingly, there are no reports of utilizing NiAl LDHs as a catalyst for organic transformations in greener condition. In the present study, we have utilized NiAl LDHs as a catalyst for the synthesis of thioxo-dihydroquinazolinones from isatoic anhydride, hydrazides and carbon disulphide. We have synthesized ten thioxo-dihydroquinazolinones with product yield ranging from 77 to 90%. The synthesized thioxo-dihydroquinazolinones possessing differently substituted aryl groups and heterocyclic ring could become a good precursors to discover and develop a new drug molecules. Nontoxic catalyst with both acidic and basic sites, substrate scope, environmental friendly solvents, one-pot operation, simple starting materials, good yields and reusability of NiAl LDHs catalyst up to five cycles are notable features of the present protocol. [ABSTRACT FROM AUTHOR]

Abstract Discovery of two-dimensional (2D) topological insulators (TIs) demonstrates tremendous potential in the field of thermoelectric since the last decade. Here, we have synthesized 2D TI, Sb2Te3 of various thicknesses in the range 65–400 nm using mechanical exfoliation and studied temperature coefficient in the range 100–300 K using micro-Raman spectroscopy. The temperature dependence of the peak position and line width of phonon modes have been analyzed to determine the temperature coefficient, which is found to be in the order of 10–2 cm−1/K, and it decreases with a decrease in Sb2Te3 thickness. Such low-temperature coefficient would favor to achieve a high figure of merit (ZT) and pave the way to use this material as an excellent candidate for thermoelectric materials. We have estimated the thermal conductivity of Sb2Te3 flake with the thickness of 115 nm supported on 300-nm SiO2/Si substrate which is found to be ~ 10 W/m–K. The slightly higher thermal conductivity value suggests that the supporting substrate significantly affects the heat dissipation of the Sb2Te3 flake.

We report on multiple excitonic resonances in bilayer tungsten diselenide (BL-WSe2) stacked at different angles and demonstrate the use of the stacking angle to control the occurrence of these excitations. BL-WSe2 with different stacking angles were fabricated by stacking chemical vapour deposited monolayers and analysed using photoluminescence measurements in the temperature range 300–100 K. At reduced temperatures, several excitonic features were observed and the occurrences of these exitonic resonances were found to be stacking angle dependent. Our results indicate that by controlling the stacking angle, it is possible to excite or quench higher order excitations to tune the excitonic flux in optoelectronic devices. We attribute the presence/absence of multiple higher order excitons to the strength of interlayer coupling and doping effect from SiO2/Si substrate. Understanding interlayer excitations will help in engineering excitonic devices and give an insight into the physics of many-body dynamics.

Abstract Synthesis of high-quality graphene layers on insulating substrates is highly desirable for future graphene-based high-speed electronics. Besides the use of gaseous hydrocarbon sources, solid and liquid hydrocarbon sources have recently shown great promises for high-quality graphene growth. Here, I report chemical vapor deposition growth of mono- to few-layer graphene directly on SiO2 substrate using ethanol as liquid hydrocarbon feedstock. The growth process of graphene has been systematically investigated as a function of annealing temperature as well as different seed layers. Interestingly, it was found that the carbon atoms produced by thermal decomposition of ethanol form sp2 carbon network on SiO2 surface thereby forming nanographene flakes via an intermediate carbon-based nanostructured state carbon nanotube. This work might pave the way to an understanding for economical and catalyst-free graphene growth compatible with current silicon-processing techniques, and it can be applied on a variety of insulating surfaces including quartz, sapphire, and fused silica.

Multi-layer MoS2 offers numerous advantages over mono-layer MoS2 in terms of improved absorption, enhanced emission and high optical density of states, which make it a better candidate for devices. However, the selective tuning of the direct-band emissions in multi-layer MoS2 is essential for various optoelectronic applications. In this work, we have demonstrated a systematic tuning of direct-band transitions in multi-layer MoS2 using Au coating prepared by sputtering and e-beam evaporation. We observed nearly 80-fold enhancement in the ratio of direct-to indirect-peak intensity with Au coating (e-beam) to that of the direct-to indirect-peak intensity of pristine samples. Along with that, complete quenching in the emissions corresponding to I-valley has been observed with Au coating. This work provides new dimensions towards the realization of plasmonic/optoelectronic devices based on multi-layer MoS2.

Advances in the hydrogen evolution reaction (HER) are intricately connected with addressing the current energy crisis and quest for sustainable energy sources. The necessity of catalysts that are efficient and inexpensive to perform the hydrogen evolution reaction is key to this. Following the ground-breaking discovery of graphene, metal thio/seleno phosphates (MPX3: M – transition metal, P – phosphorus and X – S/Se), two dimensional (2D) materials, exhibit excellent tunable physicochemical, electronic and optical properties, and are expected to be key to the energy industry for years to come. Taking this into account, a facile time-effective electrostatic restacking synthesis procedure has been followed to synthesize a 2D/2D heterostructure (FePS3@BCN) involving FePS3, one of the prominent MPX3 materials, with borocarbonitride (BCN), for hydrogen evolution reaction (HER). The piled up nanosheets of FePS3 and BCN are held together by an electrostatic force, and display extreme robustness under the harsh conditions of HER application. The amalgamated electrocatalyst achieved an overpotential of 187 mV at a current density of 10 mA cm−2 with a shallow Tafel slope of 41 mV dec−1, following the Volmer–Heyrovsky mechanism. The resilience of the electrocatalyst has been examined through chronoamperometric testing for long term stability, and it is stable for more than 14 hours, which shows the excellent electrocatalytic activity for hydrogen evolution reaction owing to the strategic approach to the catalyst design, the use of numerous electrochemically active sites, large surface area and a barrier-free channel for quick ion transfer. [ABSTRACT FROM AUTHOR]