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Quick and precise exfoliation of bulk molybdenum sulphide into few layers can bring a quantum leap in the electrochemical performance of this material.

Solar cells based on organic-inorganic lead halide perovskites are popular in the photovoltaic community due to their high efficiency, low cost, and solution processability. Understanding the fundamentals of metal halide perovskite and its interfaces is extremely important for achieving high-quality materials and developing efficient devices using these materials with the necessary properties. Various methodologies have been used to evaluate the excellent optoelectronic properties, efficiency, and stability of PSCs. In this article, we reviewed the case studies of characterization techniques to investigate structural, optical, and electrical properties of perovskite material via electron microscopic techniques (SEM and TEM), J-V measurements, AFM, XRD, and spectroscopy techniques (PL, UV-vis, XPS, Raman, FTIR, and EIS). PSCs also need to have long-term stability and large-scale applicability for successful commercialization. In this review, we studied perovskite in detail to understand the key properties of the materials to facilitate the commercialization of PSCs.

This study aims to use landfill leachate (LL) as an aqueous medium during hydrothermal carbonisation (HTC) of food waste to produce hydrochar (FWH-LL-C), which could be used as an electrode material in energy storage devices. The structural properties and electrochemical performance of the hydrochar were compared to that obtained using distilled water as a reaction medium (FWH-DW-C). The results showed that there is a difference in Brunauer–Emmett–Teller (BET) surface area of FWH-LL-C (220 m2 gm−1) and FWH-DW-C (319 m2 gm−1). The electrochemical properties were comparable, with FWH-LL-C having 227 F g−1 specific capacitance at 1 A g−1 current density and FWH-DW-C having 235 F g−1 specific capacitance at 1 A g−1 current density. Furthermore, at a power density of 634 W kg−1, FWH-DW-C achieved the highest energy density of 14.4 Wh kg−1. The energy retention capacity of the electrode was 98% which indicate that the material has an excellent energy storage capacity. The findings suggested that LL could be used as an alternative source of aqueous media during the HTC of food waste to produce hydrochar which could be used as an effective electrode material in supercapacitors.

Hollow particles can be modelled as pseudo-2 dimensional nanostructures. The electrochemical performance of such novel structures supersedes that of their solid counterparts by many folds.

The efficient monitoring and early detection of viruses may provide essential information about the disease. In this work, we have highlighted the interaction between DNA and a two-dimensional (2D) metal...

Two-dimensional (2D) materials are at the forefront of current materials research due to their exciting and unique properties. 2D tellurides are emerging materials which are yet to be fully explored. To provide an overview of this emergent field, in this review, we discuss the structure, properties, synthesis methods, and applications of selected 2D tellurides, with stoichiometry of MxTey, and MxNyTez, (M, N are metal atoms). We present a summary of the latest advances in modeling, experimental synthesis, and characterization of 2D tellurides. Additionally, stress and strain-induced tunability of the physical properties have been reviewed, with a focus on the application of 2D tellurides in electronic, optoelectronic, and magnetic devices. We have discussed many emergent quantum properties of these materials. Finally, we conclude with a perspective on the future of 2D metal tellurides.

In the past decade, several different classes of two-dimensional (2D) materials beyond graphene such as layered polymorphs of group V elements (phophorene, arsenene), Metalenes (gallenene, stanene etc.), Transition Metal–Dichalcogenides (TMDs), group III monochalcogenides, transition metal carbides as well as nitrides have been thoroughly explored. These atomically thin materials have gathered significant focus due to their unique electronic, optical, and magnetic properties, which are seldom found in their bulk counterparts due to the high surface to volume ratios and quantum confined electronic structure. These properties have led to excitement in the research community due to their potential applications in various fields of optoelectronics, energy harvesting and storage, sensing, electronics, magneto-electronics, and thermo-electronic applications. However, there is another emerging class of layered oxide 2D materials, which has been sporadically explored and lacks a systematic compilation of the made progress, potential benefits and research opportunities that may lie ahead. This specific review provides a thorough and systematic summary of research carried out on layered 2D oxides both from an experimental and theoretical perspective. Due to ultra-thin nature of the 2D metal oxides, a majority of the atoms are accessible to the surfaces, which induces new properties and applications in comparison to traditional bulk oxides. We discuss several different classes of metal oxides in their 2D forms such as MO, MOx, MxOy (where M stands for metals; x and y possible oxidation states) as well as Perovskite type oxides in this review specifically focusing on optoelectronics, sensing and electrochemical storage applications. We further make critical comparisons with bulk metal oxides, and elaborate the specific advantages of 2D metal oxides as compared to their bulk counterparts in respective applications. Finally, we conclude by providing a critical assessment and outlook of technical challenges and research opportunities for future development of layered 2D oxides.

Layered double-hydroxides (LDHs) are superior to the conventional (Transition Metal Oxides) TMOs as their lamellar morphology accommodates higher active sites contributing to the facile electron transfer towards the material degradation relations, thus attracts an immense attention for catalysis application. Moreover, the high catalytic activity of LDHs is linked to their facile anion exchange, specific electronic structures, and versatile chemical compositions. Recently, LDHs with bimetallic or ternary combinations are preferably used for hydrogenation of p-nitrophenol, a toxic and carcinogenic pollutant commonly found in industrial wastewater. Herein, a cost-effective co-precipitation fabrication protocol to obtain Ni-Co layered double hydroxide is proposed. The well-defined arrangement of active sites in the 2D structure of LDH, and the synergistic catalytic effect of Ni and Co greatly improves the efficiency for the conversion of p-nitrophenol (p-NP) to p-aminophenol (p-AMP). The catalytic performance at higher temperatures is also shown. The obtained results are further extended to explore the advantage of Ni-Co LDH as an electrocatalyst for Hydrogen Evolution Reaction (HER).

An easily scalable fabrication method has been explored to obtain atomically thin gallium telluride (GaTe), which opens up new prospective applications of this well-known material. Due to nanostruc...

Detection of volatile organic compounds (VOCs) is rapidly becoming a necessity as they have significant percentage in the indoor air pollution. Therefore, use of highly sensitive, small and portable VOC sensors ranges from households, offices to large industries. This paper deals with the use of a highly responsive semiconductor, i.e. SnO2, in VOC sensors. A hitherto unreported strategy of using hollow cage-frame-type nanostructures is proposed. These hollow particles supersede the response characteristics of solid or even the porous nanostructures, which are mostly used till date. VOCs such as: ethanol, methanol, acetone, toluene and formaldehyde can be easily detected using SnO2 hollow structures as the chemically active component of the sensor. The fabricated sensors exhibit high selectivity for each VOCs, at different operating temperature. The sensing mechanism of hollow nanostructures is also described in detail. The work can initiate significant activity on VOC sensing using hollow structures, which has remained ignored till now.

2D decorated nanostructures are fast emerging as efficient electrode materials for electrochemical devices. Au decorated SnO2, synthesized using co-precipitation and hydrothermal methods, can become a useful electrode material for supercapacitors. Au incorporation helps to mitigate the conductivity issues of SnO2 nanostructures. The superior 2D-flake like morphology leads to appreciable performance enhancement, with specific capacitance of 234 F g−1 at 1 A g−1 current density, which is much larger than that observed in pristine SnO2. The high cycling stability of Au-decorated SnO2 clearly shows its usefulness for high-performance supercapacitors. A theoretical model is also reported to explain the electrochemical results.

Graphene is being suggested as a replacement for activated carbon in energy storage devices ranging from supercapacitors to batteries. The generation of multi-heteroatom self-doped graphene structure from waste materials will be an efficient way to meet the energy requirements with its productive applications in energy devices. Here, we present a novel, high-yield synthetic strategy to prepare multi-heteroatom self-doped highly porous graphene nanosheet from Pet coke (petroleum coke). Following a comprehensive characterization of graphene using electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and its functionality in supercapacitor application is reported. The electrochemical performance of Pet graphene, in combination with 1 M H2SO4, is able to deliver specific capacitance as high as ~ 170 F/g in 0.5 A/g current density, with low equivalent series resistance. The fabricated symmetric device exhibited a maximum specific capacitance of 44 F/g at 0.5 A/g current density with an excellent energy density of ~ 8.8 Wh/Kg along with a power density of ~ 800 W/Kg at 0.5 A/g current density. The fabricated device also shows high cycling stability and Coulombic efficiency. The results establish a new protocol for the large-scale synthesis of graphene from carbonaceous waste materials, making it competitive with its low-cost counterparts.

Quantum dots (QDs) as bio-detectors have been intensively explored owing to their size dependent optical properties and are still envisioned to be used in a plethora of biomedical and healthcare areas. However, the medical application of the biosensors demands the ultrasensitive detection of the analytes, which is usually limited for the conventional methods of colorimetric and fluorescence detection. The Fluorescence Resonance Energy Transfer (FRET) process, exploited by QDs, translates the close association between the analyte and the detector into optical properties and thus promises the effective detection of biomolecules. FRET based detection systems for biomolecules utilize surface-functionalized QDs which are usually modified post production using different organic groups. In this work, a novel protocol was formulated to produce bio-functionalized QDs with controlled chemical and optical characteristics. Here, we demonstrate the first-ever biological green synthesis of MoS2 QDs using Pseudomonas aeruginosa. The bio-functionalized QDs show green luminescence with a quantum yield of 42%, supporting their application as an optical sensor. These QDs are utilized to detect the pico-molar concentration of glucose, which makes them ideal for early diabetes detection and many biomedical applications. Also, the ability to sense pico-molar levels of H2O2 opens the path for its utilization in apprehending the plant signaling pathways under stress conditions.

Recent results have shown that electrochemical energy storage devices can change their characteristics near the magnetic field environment. Mostly, this change is attributed to the magnetically res...

In recent years, graphene-based materials complexed with drugs have been developed for application in cancer therapy, aimed at gaining synergistic effect. Here, we have prepared graphene oxide (GO) and graphene quantum dots (GQDs) with curcumin (Cur) in three different ratios (1:1, 1:3, and 1:5 w/v). We showed a successful complexation of GO and GQDs with Cur through various spectroscopy and microscopy techniques. The optical density of the complex through UV-vis spectroscopy showed less than 10% (for GQDs-Cur) and less than 20% (for GO-Cur) aggregation in 48 h, which confirms the stability of the complex. The UV-vis result estimates the loading efficiency of Cur to be 80 ± 1 and 83 ± 1% for GO-Cur and GQDs-Cur respectively. We tested the complexes GO-Cur and GQDs-Cur in different ratios as an anticancer drug against human breast cancer cell lines MCF-7 and MDA-MB-468 through the MTT assay. Following 48 h of incubation with the cell lines, a cell viability of more than 75% was observed in the case of GQDsGO, while it was 40% in the case of Cur at a concentration of 100 μg/mL. The 1:1, 1:3, and 1:5 ratios of complexes enforced cell death ∼60, ∼80, and ∼95% at 100 μg/mL after 48 h of treatment, respectively. The optical images of cancerous cells treated with GO, GQDs, Cur, GO-Cur, and GQDs-Cur, at three different time intervals (0, 24, and 48 h), corroborated well with the results from the MTT assay in terms of the percentage of dead cells. The fluorescence images show a successful delivery of Cur drug inside the cancerous cell. The possible mechanism of killing of the cancerous cell with the complexes GO-Cur and GQDs-Cur is discussed. Moreover, this study opens a window to determine the mechanism of killing the cancerous cell.

Porous electrodes are fast emerging as essential components for next generation supercapacitors. Using porous structures of Co3O4, Mn3O4, alpha Fe2O3, and carbon, their advantages over the solid counterpart is unequivocally established. The improved performance in porous architecture is linked to the enhanced active specific surface and direct channels leading to improved electrolyte interaction with the redox active sites. A theoretical model utilizing the Fick's law is proposed, that can consistently explain the experimental data. The porous structures exhibit nearly 50 - 80 percentage increment in specific capacitance, along with high rate capabilities and excellent cycling stability due to the higher diffusion coefficients.

Recent trends in sodium-ion-based energy storage devices have shown the potential use of hollow structures as an electrode material to improve the performance of these storage systems. It is shown that, in addition to the use of hierarchical structures, the choice of the complementary carbon electrode determines the final performance of Na-ion-based devices. Here, we present simple synthesis strategies to prepare different structured carbonaceous materials that can be upscaled to an industrial level. Individual carbon materials deliver specific capacitance ranges from 120 to 220 F g

A comprehensive temperature and high-pressure investigation on BiGdO

The physical and chemical properties of the colloidal solution change as a function of the concentration of nanoparticles. Here, we have studied the effect of systematic ultra-low dilution (up to 10200 times) of gold nanoparticle colloidal, revealing the mechanism of colloidal formation in such extreme dilution. Optical spectroscopy confirms the presence of nanoparticles with narrow size distribution and high surface activity in higher dilutions (up to 10200 times) colloidal solution. Particle size analysis of the serially diluted solution shows that the size distribution becomes more-narrow with increasing dilution. Transmission electron microscopy confirm the presence of nanoparticle up to 10200 times dilution. The process of dilution introduces an active carbon layer on these particles. The understanding of such extreme dilution can be utilized in biomedical applications, especially in the Homoeopathy system.

Introduction of graphene into the stable matrix of Mn3O4-polyaniline composite leads to supercapacitor electrode that can deliver specific capacitance >1000 F g−1. This is nearly double the value, which is observed in conventional type Mn3O4-polyaniline composite that is able to deliver ~500 F g−1, at a scan rate of 5 mV s−1 in the voltage window −1 to 1 V. This value is also much greater than those obtained in most of the niche carbon or transition metal oxide based supercapacitors. Cycling studies, carried out at a current density 25 A g−1 and for 3000 cycles, indicated that the composite continue to retain nearly ~97% of the initial capacitance. The enhancement can be explained in terms of the connected percolated conductive path, which originates due to the dispersed graphene sheets.

SiO $_{2}$ –HfO $_{2}$ rib waveguides were fabricated using the UV-photolithography method followed by wet chemical etching technique. Graphene oxide (GO) integrated SiO $_{2}$ –HfO $_{2}$ rib waveguide works as an on-chip TE-pass waveguide polarizer and also allows controlled intensity tuning of the selective state of polarization when irradiated using a 532 nm ns laser. The tuning of the TE polarization intensity was confirmed by performing the experiments at three different pump fluences viz., 0.2, 0.3, and 0.6 mJ/cm $^{2}$ , wherein at low pump fluence, TE polarization intensity showed more controlled absorption. The results indicate that GO integrated glass waveguides can act as efficient polarization dependent power splitters for integrated optic applications.

Hierachical nanosheets of Co3O4 can deliver specific capacitance of ∼402 F g–1, which is 50% higher than that obtained using simpler disc shaped (∼230 F g–1) or conventional solid structures (∼150 F g–1). A simple question is then asked: should the particles showing other morphologies be discarded? As the electrode material is to be used in green or renewable energy technologies, the carbon footprint of each particle morphology was determined using the life cycle assessment (LCA) studies. The results led to inferences, which were strikingly different from those generally expected. It was seen that simpler morphologies, prepared using easier synthesis protocols, had five-times lower CO2 footprints than hierarchical morphology (nanosheets). The results become extremely critical for proposing their large scale industrial use. They clearly indicate that the choice of nanostructured metal oxides in energy storage devices will have to be relooked from the aspect of their own environmental impacts. Particles wit...

Quantum dots (QDs) as bio-detectors have been intensively explored owing to their size dependent optical properties and are still envisioned to be used in a plethora of biomedical and healthcare areas. However, the medical application of the biosensors demands the ultrasensitive detection of the analytes, which is usually limited for the conventional methods of colorimetric and fluorescence detection. The Fluorescence Resonance Energy Transfer (FRET) process, exploited by QDs, translates the close association between the analyte and the detector into optical properties and thus promises the effective detection of biomolecules. FRET based detection systems for biomolecules utilize surface-functionalized QDs which are usually modified post production using different organic groups. In this work, a novel protocol was formulated to produce bio-functionalized QDs with controlled chemical and optical characteristics. Here, we demonstrate the first-ever biological green synthesis of MoS2 QDs using Pseudomonas aeruginosa. The bio-functionalized QDs show green luminescence with a quantum yield of 42%, supporting their application as an optical sensor. These QDs are utilized to detect the pico-molar concentration of glucose, which makes them ideal for early diabetes detection and many biomedical applications. Also, the ability to sense pico-molar levels of H2O2 opens the path for its utilization in apprehending the plant signaling pathways under stress conditions.

Self-assembled hierarchical nanostructures are slowly superseding their conventional counterparts for use in biosensors. These morphologies show high surface area with tunable porosity and packing density. Modulating the interfacial interactions and subsequent particle assembly occurring at the water-and-oil interface in inverse miniemulsions, are amongst the best strategies to stabilize various type of hollow nanostructures. The paper presents a successful protocol to obtain CeO

A detailed temperature and pressure investigation on BiGdO$_{3}$ is carried out by means of dielectric constant, piezoelectric current, polarization-electric field loop, Raman scattering and x-ray diffraction measurements. Temperature dependent dielectric constant and dielectric loss show two anomalies at about 290 K (T$_r$) and 720 K (T$_C$). The later anomaly is most likely due to antiferroelectric to paraelectric transition as hinted by piezoelectric current and polarization-electric field loop measurements at room temperature, while the former anomaly suggests reorientation of polarization. Cubic to orthorhombic structural transition is observed at about 10 GPa in high pressure x-ray diffraction studies accompanied by anisotropic lattice parameter changes. An expansion about 30 % along $a$-axis and 15 % contraction along $b$-axis during the structural transition result in 9.5 % expansion in unit cell volume. This structural transition is corroborated by anomalous softening and large increase in full width half maximum (FWHM) of 640 cm$^{-1}$ Raman mode above 10 GPa. Enhancement of large structural distortion and significant volume expansion during the structural transition indicate towards an antiferroelectric to ferroelectric transition in the system., 20 pages, 7 figures