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Nanodiamonds (NDs) were prepared by utilizing a microplasma facility. Ethanol and Argon mixture was decomposed in microplasma for the formation of NDs. In order to stabilize the NDs growth, the Hydrogen was added in the mixture during the growth process. Hydrogen flow rate was changed from 1 to 5 L/min to find out the optimum flow rate for the growth of stabilized NDs. The experiments were also performed without the introduction of Hydrogen for the comparison. TEM and Raman analysis confirm that the highest quality diamonds are obtained at Hydrogen flow rate of 3L/min. In the case of Hydrogen, the SAED patterns reveal the presence of pure diamond phases which in turn envisages the etching of graphitic shell. TEM micrographs reveal that the size of NDs produced at 3 L/min Hydrogen flow rate ranges from 1~20 nm which is much smaller than that of without Hydrogen (4-32 nm). EDX spectra also disclose the Carbon peak with a maximum intensity for 3 L/min flow rate. UV-Visible and PL spectroscopy analysis indicate the presence of Nitrogen-Hydrogen defect centers. However, a decrease in defect density at 3L/min indicates the production of improved quality NDs. FTIR also verifies the removal of graphitic shell around NDs at 3 L/min flow rate. Moreover, high hydrogen flow rates effectively incorporate nitrogen vacancy (NV) defects. Prepared NDs offer emerging applications in optoelectronic systems, biomedical nanodevices and nanoscale sensors for electric field, magnetic field & temperature.

Thin films of zinc doped aluminum antimonide (Zn:AlSb) have been dumped on glass substrate using chemical bath deposition method. The morphological, structural, as well as optical properties of deposited thin films are investigated using XRD, optical microscopy, and UV-V is spectroscopy along with four-point probe technique. The XRD results exhibit that Zn is doped in AlSb and maximum grain size has been obtained at 4% Zn-concentration. Optical micrographs of pure and zinc doped aluminum antimonide (AlSb) at different concentrations of Zn have been shown to confirm the doping by observing changes in morphology and it has been observed that optimized films of AlSb are obtained at 4% of Zn-content. The optical bandgap of Zn doped AlSb films at varying concentrations of 0%, 1%, 2%, 3% and 4% has been found to decrease with enhancement in Zn-concentration and values are measured as 1.8, 1.7, 1.6, 1.4, and 1.3 eV respectively. The sheet resistivity also depends on Zn-content and has been observed to decrease as AlSb is doped with Zn, indicating an increase in electrical conductivity. The explored results indicate a significant potential of these deposited thin films to be used in photonics, photocatalysis, and energy industry.

This study is aimed to investigate laser irradiation effects on the surface, structural, and mechanical properties of iron samples. The prepared samples have been treated for multiple exposure times using continuous-wave diode laser with a wavelength of 532 nm in a laboratory environment. The structural as well as surface modifications of laser exposed targets are explored via scanning electron microscope and X-ray diffractometer. The SEM analysis revealed micrometer grain size, exfoliational sputtering, and crater formation, while XRD patterns were used to investigate d-spacing, and grain size of laser exposed samples. The mechanical characteristics of laser-ablated materials were examined using a micro Vickers hardness-tester, and microhardness has been explored as a function of increasing laser exposure time. It has been observed that grain size reduces while hardness of polycrystalline iron increases with increase in exposure time.

In this study, novel hydrothermal synthesis is used to explore the impact of photocatalytic activity on H2 production using an aqueous solution of triethanolamine (TEoA) in TiO2 nanostructures designed with varying molar concentrations of HCl, and the production of molecular hydrogen is explored as a function of molar concentration. A solar simulator is utilized to assess the photocatalytic activities of methyl orange degradation under UV light irradiation and molecular H2 production. Also, XRD patterns and SEM images are explored to show agglomerated nanoparticle formation, and an EDX spectrum is employed to confirm TiO2 compositions. The band gap analysis of produced nanostructures is performed using a UV-Vis spectrometer and is found to be varying in between 2.5 and 3.0 eV, while the maximum methyl orange degradation corresponds to 1.0 M concentration of HCl, indicating an enhanced hydrogen production. To meet the foreseeable future energy crises and worsening environmental challenges, we may need sustainable energy sources, and photocatalysis molecular H2 production offers a viable alternative to fossil fuels that can be employed to tackle future difficulties.

As a consequence of rising concern about the impact of fossil fuel-based energy on global warming and climate change, photovoltaic cell technology has advanced significantly in recent years as a sustainable source of energy. To date, photovoltaic cells have been split into four generations, with the first two generations accounting for the majority of the current market. First generation of thin-film technologies is based on monocrystalline or polycrystalline silicon and gallium arsenide cells and includes well-known medium- or low-cost technologies with moderate yields, whereas, second generation includes devices with lower efficiency and manufacturing costs. Third generation is based on novel materials and has a wide range of design options, as well as expensive but highly efficient cells. However, fourth generation, also known as “inorganics-in-organics,” combines the low cost and flexibility of polymer thin films with the durability of innovative inorganic nanostructures (metal nanoparticles or metal oxides) in organic-based nanomaterials (carbon nanotubes, graphene, and their derivatives). The aim of this chapter was to highlight the current state of photovoltaic cell technology in terms of manufacturing materials and efficiency by providing a comprehensive overview of the four generations as well as the relevance of graphene and its derivatives in solar cell applications.

Liquid crystal (LC) is a fascinating state of matter that combines order and mobility at multiple hierarchical levels, spanning from nanoscale to the macroscale, or from molecular to the macroscopic, and is composed of molecules and layers as thin as of a few nanometer in size. This unique combination allows such a system to adapt to a wide range of external stimuli, including temperature, magnetic field, electric field, mechanical stress, light, chemical reaction, and electrochemical response, by determining a new lowest energy configuration. Liquid crystalline nanostructures efficiently transmit and amplify information and attributes over macroscopic sizes due to their dynamic nature. The responsiveness and diversity of LCs provide enormous potential and challenges for fundamental scientific insights as well as opening the door to countless applied applications. Recent breakthroughs in nanotechnology have boosted the discipline, both in terms of theoretical simulations and the ability to fabricate nanoscale structures such as sub-wavelength gratings, nanoporous materials, and nanoparticles. Because LC materials are switchable, a new family of active plasmonic and nanophotonic devices is emerging, describing fascinating basic research processes as well as the creation of upgraded devices. This chapter discusses the fundamentals, computational advances, future prospects and challenges, as well as potential applications of LCs.

Density Functional Theory (DFT) is a powerful and commonly employed quantum mechanical tool for investigating various aspects of matter. The research in this field ranges from the development of novel analytical approaches focused on the design of precise exchange-correlation functionals to the use of this technique to predict the molecular and electronic configuration of atoms, molecules, complexes, and solids in both gas and solution phases. The history to DFT’s success is the quest for the exchange-correlation functional, which utilizes density to represent advanced many-body phenomena inside one element formalism. If a precise exchange-correlation functional is applied, it may correctly describe the quantum nature of matter. The estimated character of the exchange-correlation functional is the basis for DFT implementation success or failure. Hohenberg-Kohn established that every characteristic of a system in ground state is a unique functional of its density, laying the foundation for DFT, which is being utilized to explore the novelty of materials. This chapter is aimed to present an overview of DFT by explaining the theoretical background, commonly used approximations as well as their recent developments and challenges faced along-with new horizons.

BiOI is a visible photocatalyst towards organic pollutant. In this work, biomass waste (withered typha grass) was used to fabricate nitrogen-doped hierarchical carbon (NHC) by an one-step carbonization route. Then NHC provided a good carrier to load the BiOI semiconductor materials by a green simple co-precipitation method, after adding NaOH solution, the irregular microspheres BiOI/NHC was gradually etched by OH− to form the tremella-like Bi4O5I2/NHC. The well-defined tremella-like Bi4O5I2/NHC invested adequate interface and high particular surface range (SBET: 66 m2 g−1), which is higher than pure BiOI (22 m2 g−1) and Bi4O5I2 (17 m2 g−1). Multiple synergistic effects, such as high SBET can give more dynamic destinations, the special tremella-like structure can assimilate more reflected occurrence light of other nanosheets, low I content can increase the conduction/valence band gap of semiconductor materials and NHC can act as an electron acceptor, making as-prepared Bi4O5I2/NHC composite ideal candidates for photocatalysis. The degradation rate of Bi4O5I2/NHC reaches up to 87.4% of methyl orange in 2 h, which is about 2 times higher than BiOI and Bi4O5I2. Therefore, this work gives a technique to link NHC derived from biomass waste to Bi4O5I2 with highly-efficiency photocatalytic performance.

This study investigates the photocatalytic degradation of nitrogen oxides over graphitic carbon nitride (g-C3N4) based photocatalysts. The synthesis procedure of g-C3N4 consists of two-step: in the first step, the synthesis of g-C3N4 is carried out through a microwave heating method, whereas in the second step the as-synthesized product is annealed. The characterization was carried out by XRD (X-ray Diffraction), FESEM (Field Emission Scanning Electron Microscopy), TEM (Transmission Electron Microscopy), BET (Brunauer-Emmet-Teller), and XPS (X-ray Photoelectron Spectroscopy). Photocatalytic activities for the degradation of NOx (Nitrogen Oxides) are compared with commercial TiO2 and g-C3N4, to investigate the structural and physio-chemical features of prepared samples and their correlation with the catalytic activity. The results show that g-C3N4 nanosheets have better activity and stability as compared to TiO2. The deposition effect of 1 wt% Pt to the g-C3N4 nanosheets is also observed which puts a negative effect on the degradation results.

The development of green and clean synthetic techniques to overcome energy requirements have motivated the researchers for the utilization of sustainable biomass. Driven by this desire we choose rice as starting materials source. After the explosion effect, the precursor is converted into puffed rice with a honeycomb-like structures composed of thin sheets. These honeycomb-like macrostructures, effectively prevent the cross-linking tendency towards the adjacent nanosheets during activation process. Furthermore, tuneable micro/mesoporous structures with ultrahigh specific surface areas (SBET) are successfully designed by KOH activation. The highest SBET of 3326 m2 g−1 with optimized proportion of small-mesopores is achieved at 850 °C. The rice-derived porous N-doped carbon nanosheets (NCS-850) are used as the active electrode materials for supercapacitors. It exhibites high specific capacitance specifically of 218 F g−1 at 80 A g−1 in 6 M KOH and a high-energy density of 104 Wh kg−1 (53 Wh L−1) in the ionic liquid electrolytes. These are the highest values among the reported biomass-derived carbon materials for the best of our knowledge. The present work demonstrates that the combination of “puffing effect” and common chemical activation can turn natural products such as rice into functional products with prospective applications in high-performance energy storage devices.

Water oxidation or oxygen evolution reaction (OER) electrocatalysis got much attention in the last few years because of its prime role in water splitting, rechargeable metal-air batteries and fuel cells. Therefore, the development of efficient, abundant and economical catalysts for water oxidation reaction is one of the main subjects of present study in renewable energies. This review article summarizes the very recent efforts in the field of OER electrocatalysis along with the faced challenges. The solutions to these challenges also outline with appropriate examples of scientific literatures. Significantly, the present review will provide the standards to evaluate the activity and stability for heterogeneous OER catalysts. It will clearly summarize the future directions and applications, especially the combination of sustainable energy utilization (like triboelectric nanogenerator) with water splitting. The providing study will help to explore and develop better catalysts and units for practical applications and will offer basic understanding of OER process along with the standard parameters to evaluate the performance.

The purpose of this study is to develop an active, low cost, non-precious, stable, and high-performance catalyst for oxygen reduction reaction (ORR). In this regard, Mn2O3-decorated nitrogen-doped carbon nanosheets (Mn2O3/NC) are fabricated by a two-step strategy involving a hydrothermal method and a solid-state method. In the resultant structures, very fine Mn2O3 nanoparticles with an average size of about 5 nm are strongly attached to nitrogen-doped carbon nanosheets. The role of the Mn2O3 nanoparticles is to provide active sites for ORR, while the presence of the nitrogen-doped carbon not only enhances the conductivity of the overall structure but is also helpful for overall stability. The Mn2O3/NC shows good onset potential (0.80 V@−1 mA/cm2), methanol crossover effect, and stability (90%).

This work focuses on the synthesis of heterostructures with compatible band positions and a favourable surface area for the efficient photocatalytic production of molecular hydrogen (H2). In particular, 3-dimensional Nb2O5/g-C3N4 heterostructures with suitable band positions and high surface area have been synthesized employing a hydrothermal method. The combination of a Nb2O5 with a low charge carrier recombination rate and a g-C3N4 exhibiting high visible light absorption resulted in remarkable photocatalytic activity under simulated solar irradiation in the presence of various hole scavengers (triethanolamine (TEOA) and methanol). The following aspects of the novel material have been studied systematically: the influence of different molar ratios of Nb2O5 to g-C3N4 on the heterostructure properties, the role of the employed hole scavengers, and the impact of the co-catalyst and the charge carrier densities affecting the band alignment. The separation/transfer efficiency of the photogenerated electron-hole pairs is found to increase significantly as compared to that of pure Nb2O5 and g-C3N4, respectively, with the highest molecular H2 production of 110 mmol/g·h being obtained for 10 wt % of g-C3N4 over Nb2O5 as compared with that of g-C3N4 (33.46 mmol/g·h) and Nb2O5 (41.20 mmol/g·h). This enhanced photocatalytic activity is attributed to a sufficient interfacial interaction thus favouring the fast photogeneration of electron-hole pairs at the Nb2O5/g-C3N4 interface through a direct Z-scheme.

BiOI is a visible photocatalyst towards organic pollutant. In this work, biomass waste (withered typha grass) was used to fabricate nitrogen-doped hierarchical carbon (NHC) by an one-step carbonization route. Then NHC provided a good carrier to load the BiOI semiconductor materials by a green simple co-precipitation method, after adding NaOH solution, the irregular microspheres BiOI/NHC was gradually etched by OH

Photocatalysis is a highly promising technique to address the challenges of environmental and energy aspects. TiO2 is currently in commercial use, but due to its wide bandgap, it is limited to UV region which is 5% of total solar energy spectrum. Moreover, the fast recombination rates of photo-generated charge carriers have also limited its photocatalytic efficiency. Substantial efforts have been made over the past few years to engineer various semiconductor photocatalysts. Numerous strategies have been employed to improve photocatalytic efficiency by tuning the bandgap such as developing type-II and Z-scheme, lowering the recombination rate, increase the surface kinetics, etc. The main objectives of this special issue are to cover challenges and recent progresses in engineering/designing, synthesis, characterization and establishing efficient/advanced photocatalytic systems which are addressed [...]

We propose a novel idea to utilize environment pollutant cigarette ash for energy storage material as electrode of supercapacitors as supercapacitors can deliver high power and reasonable energy densities as compared to batteries which deliver energy as a result of chemical reactions and suffer with low power densities. Keeping in view this advantage and research focus in this field, supercapacitors of cigarette ash were fabricated as energy storage devices. The electrode composed of ash shows specific capacitance of 183.33 F/g at current density of 1 A/g for 1st cycle and 165 F/g for 2000th cycle which indicate its remarkable long-term cyclic stability in Na2SO4 electrolyte.

Nb2O5 appeared as a promising candidate for a large number of applications. In the present work novel, 3D-hollow hierarchical Nb2O5 superstructures are prepared by self-organization of mesorods. The work emphasizes on the synthesis and detailed investigation of 3D-hollow hierarchical Nb2O5 superstructures, which are attained by two-step, template-free hydrothermal synthesis route. The obtained orthorhombic(T)-Nb2O5 superstructures have shown a high crystallinity, with a wide band gap of 3.1 eV. Among semiconductor oxides Nb2O5 with different morphologies are less explored due to complicated synthesis, growth and nucleation process. Thus, in general, factors involved for self-organized superstructures are not studied in detail. In this context, assembly of T-Nb2O5 superstructures is investigated in depth by applying SEM, TEM and UV/Vis absorption measurements. Based on the realized results a formation mechanism is proposed, which is further strengthened by the time and precursor dependent experiments. In addition, asymmetric supercapacitor properties of T-Nb2O5 superstructures are studied for the first time by using an inorganic electrolyte. The devised T-Nb2O5 superstructures have demonstrated excellent supercapacitor performance. The supercapacitor is operated at a wide potential window of 2.5 V in Na2SO4 electrolyte and exhibited high power density (650 W/Kg), energy density (86 Wh/Kg) with good cycling capability.

Catalysts for oxygen and hydrogen evolution reactions (OER/HER) are at the heart of renewable green energy sources such as water splitting. Although incredible efforts have been made to develop efficient catalysts for OER and HER, great challenges still remain in the development of bifunctional catalysts. Here, we report a novel hybrid of Co3O4 embedded in tubular nanostructures of graphitic carbon nitride (GCN) and synthesized through a facile, large-scale chemical method at low temperature. Strong synergistic effects between Co3O4 and GCN resulted in excellent performance as a bifunctional catalyst for OER and HER. The high surface area, unique tubular nanostructure, and composition of the hybrid made all redox sites easily available for catalysis and provided faster ionic and electronic conduction. The Co3O4@GCN tubular nanostructured (TNS) hybrid exhibited the lowest overpotential (0.12 V) and excellent current density (147 mA/cm2) in OER, better than benchmarks IrO2 and RuO2, and with superior durability in alkaline media. Furthermore, the Co3O4@GCN TNS hybrid demonstrated excellent performance in HER, with a much lower onset and overpotential, and a stable current density. It is expected that the Co3O4@GCN TNS hybrid developed in this study will be an attractive alternative to noble metals catalysts in large scale water splitting and fuel cells.

The hierarchical nanostructures (HNs) have engrossed immense attention due to their superior performance in catalysis, electronic and energy storage/conversion devices. The multicomponent transition metal oxides (TMOs) have been pointed out as more promising materials for advanced technological applications as compared to their counter binary oxides. Due to the advantages of hierarchical nanostructures and TMOs we have synthesized novel Zn2V2O7 hierarchical nanostructures using template free route. The photoluminescence of the sample exhibited an emission at 553.65 nm which can be useful for light emission devices. The hydrogen storage of Zn2V2O7 HNs were measured at 473 K and 573 K with an absorption of 1.21 wt.% and 1.81 wt.%., respectively. These studies point out a new class of nanomaterials for possible applications for energy storage and green emission optoelectronic devices.

Niobium pentoxide (Nb2O5) has attracted considerable interest owing to its potential applications. A facile surfactant and template free hydrothermal method has been adopted to synthesize novel nanoflowers of Nb2O5. The incomplete oxidation process was completed by annealing in air at 400°C for 1 h. The initial band gap value varied from 3.1 eV to 2.9 eV with a red shift of 27.5 nm. Time dependent experiments were performed to understand growth mechanism. RhB under visible light was degraded by using Nb2O5 nanoflowers before and after annealing. The photdegradation constant k: 0.89 h-1 and 2.62 h-1 were calculated, respectively. The rate constant of Nb2O5 nanoflowers after annealing was found larger than commercial Nb2O5, Commercial TiO2 Degussa P25, HTiNbO5, N-TiO2, SnNb2O6 nanosheets, Bi3NbO7 nanocomposites and C, N-codoped InOOH microspheres.

Hierarchical porous nitrogen-doped carbon (HPNC) nanosheets (NS) have been prepared via simultaneous activation and graphitization of biomass-derived natural silk. The as-obtained HPNC-NS show favorable features for electrochemical energy storage such as high specific surface area (SBET: 2494 m(2)/g), high volume of hierarchical pores (2.28 cm(3)/g), nanosheet structures, rich N-doping (4.7%), and defects. With respect to the multiple synergistic effects of these features, a lithium-ion battery anode and a two-electrode-based supercapacitor have been prepared. A reversible lithium storage capacity of 1865 mA h/g has been reported, which is the highest for N-doped carbon anode materials to the best of our knowledge. The HPNC-NS supercapacitor's electrode in ionic liquid electrolytes exhibit a capacitance of 242 F/g and energy density of 102 W h/kg (48 W h/L), with high cycling life stability (9% loss after 10,000 cycles). Thus, a high-performance Li-ion battery and supercapacitors were successfully assembled for the same electrode material, which was obtained through a one-step and facile large-scale synthesis route. It is promising for next-generation hybrid energy storage and renewable delivery devices.

Highly efficient visible-light-driven WO3/Fe2(WO4)3·10.7H2O porous microplates have been fabricated for the first time by a simple one-step hydrothermal method using sodium tungstate and iron chloride as precursors. The photocatalyst was characterized by employing X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-VIS absorption, photoluminescence (PL), and Fourier transform infrared spectroscopy (FTIR). From the FESEM and TEM analysis, the size of as-prepared porous microplates was estimated to be ca. 2 μm. The as-prepared sample maintained a high specific surface area (96.906 m2 g−1) and showed remarkably high photocatalytic performance (k = 0.06771 min−1) for the degradation of methyl orange (MO) under visible light irradiation. The improved performance of the product was found to be 3.3 times greater than pure WO3 and about 6.7 times greater than that of P25 TiO2. The enhanced optical absorption in the visible region, large specific surface area, suitable band position and efficient separation of photogenerated electron–hole pairs at the heterojunction interface between the two materials were the key factors involved in the enhancement of the photocatalytic activity.

In this study, we have used a facile, economical and scalable synthetic technique for the fabrication of super long V2O5 nanobelts. The as synthesized product was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), high resolution transmission electron microscopy and selected area electron diffraction (SAED). The nanobelts had an optical bandgap of 2.3 eV. The Raman spectrum confirmed the pure state of the V2O5 nanobelts. A low turn-on field of 1.4 V μm−1 and a threshold field of 2.13 V μm−1 were obtained for the V2O5 super long nanobelts. Carrier concentrations, Nd = 1.48 × 1018 cm−3; electron mobility = 1.26 cm2 V−1 s−1; and conductivity = 36.1 S m−1 were calculated using the metal-semiconductor-metal (MSM) model. Field emission measurements along with the electrical characteristics of V2O5 nanobelts indicate that they could be promising candidates for applications in field emission displays, electron emission devices and vacuum microelectronic devices.

Mesoporous nickel cobaltite (NiCo2O4) nanosheets are synthesized using a cost effective, ultra fast and environmentally friendly microwave assisted heating method followed by a post-calcination process of the as-prepared precursors. XRD, XPS, BET, SEM, TEM and HRTEM methods are used to characterize the nanosheets. The as-prepared nanosheets with a thickness of around 2 nm possess many interparticle mesopores. The nanosheets have a mesoporous structure, high specific surface area (111.15 m2 g−1), large pore volume (0.3033 cm3 g−1) and narrow pore size distribution (2.25–10 nm). A flexible supercapacitor working electrode of the mesoporous NiCo2O4 nanosheets is prepared on carbon cloth. Cyclic voltammetry, chronopotentiometry and impedance spectroscopy measurements are used to investigate the electrochemical performance of the as-prepared mesoporous NiCo2O4 nanosheet/carbon cloth electrode. The mesoporous NiCo2O4 nanosheets exhibit specific capacitances of 292.5 and 200 F g−1 in 2 M KOH aqueous electrolyte at current densities of 1 and 8 A g−1 respectively. The cyclic performance indicates excellent capacitance retention of 94.5% after 2000 cycles at a current density of 3 A g−1. The excellent cyclic stability can be attributed to the mesoporous nature, high specific surface area, large pore volume and narrow pore distribution of the nanosheets. The synthesized mesoporous NiCo2O4 nanosheets using a microwave method are proved to be excellent electrode material for advanced flexible supercapacitors.

A novel Z-scheme WO3/CdWO4 photocatalyst has been fabricated with sheet-like tungsten trioxide (WO3) hybridized by rod-like cadmium tungstate (CdWO4) via a hydrothermal and chemisorption method. The as-synthesized WO3/CdWO4 photocatalyst exhibited enhanced photocatalytic efficiency for the degradation of different organic dyes under visible light irradiation. It was found that the photocatalytic performance of the composite WO3/CdWO4 was much higher than that of either WO3 or CdWO4 for the degradation of each organic dye. The highest activity of the composite was recorded for the degradation of MB which was about 7 times greater than pure CdWO4 and 2.3 times that of pure WO3. The enhanced performance of the photocatalyst was mainly attributed to the increased surface area and introduction of WO3 into the composite sample, which can induce higher adsorption activity for organic dyes and increased electron–hole separation at the interface between two semiconductors by establishing an inner electric field.

Hierarchically structured covellite copper sulfide (CuS) microflowers composed of nanosheets have been successfully fabricated via a one-pot sonochemical process, using copper sulfate and thiourea aqueous solution as precursors in the presence of citric acid, without any prefabricated template. Large-scaled architectures are homogeneous and quite separately displaced and assembled by pure hexagonal single-crystalline CuS nanosheets, having thickness within 20 nm. The as obtained hierarchical CuS structures possess rather high surface area and unique double pore size distributions measured from N2 adsorption isotherms. Moreover, a possible growth mechanism for the CuS hierarchical architectures is proposed on the basis of temporal evolution controlled experiments. Most importantly, these hierarchically structured CuS catalysts showed highly efficient and versatile photo-catalytic activities as well as excellent recyclability in degrading highly concentrated dye aqueous solutions of methylene blue (MB), rhodamine B (RhB) and their mixed solution (MB + RhB) with the help of hydrogen peroxide (H2O2) under natural light irradiation, suggesting a promising application in wastewater purification.

Tin dioxide (SnO 2 ) ultralong nanobelts were fabricated on silicon substrate by metal catalyzed Chemical Vapor Deposition (CVD) approach. An optical bandgap of 3.66 eV was calculated by optical absorbance data. Three Raman active modes peaks were observed at 474.4, 633 and 774.4 cm −1 . Room temperature photoluminescence (PL) exhibited an orange emission at 600 nm. A vapor–liquid–solid (VLS) process based growth mechanism for the formation of SnO 2 nanobelts was proposed and discussed briefly. Electrical transport characteristics of nanobelts were studied in dark and under ultraviolet (UV) laser. The fabricated device exhibited high photo-response properties under UV light, indicating their potential application as photo-switches and UV detectors.

A two step, facile surfactant free hydrothermal route was adopted to synthesize Nb3O7F novel hollow microflowers (NHMF). Time dependent experiments were performed which suggested Nb3O7F-NHMF were formed due to Ostwald-ripening process. Raman spectroscopy was conducted to understand different vibrational modes of Nb3O7F-NHMF. Its characteristic band at 692 cm−1 was observed which is associated to NbO6 octahedron sharing. The bandgap of 3.2 eV was calculated by using UV-VIS-NIR absorption spectrum. Considering importance of layered structures in energy storage applications, hydrogen storage ability of Nb3O7F-NHMF were measured for the first time. The maximum values of hydrogen absorption for Nb3O7F-NHMF at 373 K and 473 K were 0.789 wt.% and 1.08 wt.%, respectively. The hydrogen storage measurements revealed the potential of Nb3O7F-NHMF as prospective material for energy storage applications.

We first report the catalyst free growth of indium selenide microwires through a facile approach in a horizontal tube furnace using indium and selenium elemental powders as precursors. The synthesized microwires are γ-phase, high quality, single crystalline and grown along the [112̅0] direction. The wires have a uniform diameter of ∼1 μm and lengths of several micrometers. Photodetectors fabricated from synthesized microwires show reliable and stable photoresponse exhibiting a photoresponsivity of 0.54 A/W, external quantum efficiency of 1.23 at 633 nm with 4 V bias. The photodetector has a reasonable response time of 0.11 s and specific detectivity of 3.94 × 10(10) Jones at 633 nm with a light detection range from 350 to 1050 nm, covering the UV-vis-NIR region. The photoresponse shown by single wire is attributed to direct band gap (Eg = 1.3 eV) and superior single crystalline quality. The photoresponsive studies of single microwires clearly suggest the use of this new and facile growth technique without using catalysts for fabrication of indium selenide microwires in next-generation sensors and detectors for commercial and military applications.

We present first study on ZnV 2 O 4 glomerulus nano/microspheres synthesize by template free route to expose its hydrogen storage potential. Besides this the evolution of nano/microspheres has been investigated in detail. To reveal possible growth mechanism of these spheres, time-dependent experiments are performed. Reitveld analysis is taken into account for calculation of lattice parameters, crystallite size and strain. From our results, a correlation between lattice parameters and crystallite size is observed. The strain decreases with the increase in reaction time. Hydrogen storage measurement reveals potential of ZnV 2 O 4 nanospheres as a prospective material for energy storage applications. These studies can open new avenue of research for hydrogen storage in spinel oxide materials.

A variety of well defined, highly symmetrical, super complex and hierarchical architectures of covellite copper sulfide have been successfully prepared by a simple solvothermal approach. The effects of various influencing parameters on the formation of CuS hierarchical architectures were precisely investigated and a possible formation mechanism has been elucidated. The reaction time was found to be a critical factor in controlling the CuS architecture and highly complex structures were obtained with elongated reaction times. The as-synthesized architectures exhibited excellent photocatalytic activities in the visible region for the degradation of individual dyes (methylene blue and rhodamine B) and their mixed solutions in the presence of H2O2. The efficient photocatalytic activity can be attributed to the carefully controlled hierarchical CuS structures. Overall, this study is of great importance in the “bottom-up” assembly of copper sulfide nanoplates to obtain highly complex structures which offer a good opportunity to understand the fundamental significance of atypical structures for their potential applications.

We have developed a facile, scaled up, efficient and morphology-based novel WO3–g-C3N4 photocatalyst with different mass ratios of WO3 and g-C3N4. It was used for the photodegradation of rhodamine B (RhB) under visible light irradiation and it showed excellent enhanced photocatalytic efficiency as compared to pure g-C3N4 and WO3. The apparent performance of the composite/hybrid was 3.65 times greater than pure WO3 and 3.72 times greater than pure g-C3N4 respectively, and it was also found to be much higher than the previously reported ones. Furthermore, the optical properties of composite samples were evaluated. The bandgap of composite samples lies in the range of 2.3–2.5 eV, which was favourable for photodegradation. The possible mechanism for enhanced catalytic efficiency of the WO3–g-C3N4 photocatalyst is discussed in detail. It was found that the enhanced performance is due to the synergistic effect between the WO3 and g-C3N4 interface, improved optical absorption in the visible region and suitable band positions of WO3–g-C3N4 composites.

Three dimensional (3D) novel tungsten trioxide (WO3) octahedra have been prepared by a simple surfactant/catalyst-free hydrothermal method. The phase and morphological structure of the as-synthesized material were analysed by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray (EDX) spectroscopy and X-ray photoelectron spectroscopy (XPS). FESEM results showed that the as-prepared WO3 octahedron structure was in the range of 1–5 μm. Furthermore, the optical properties like the UV-VIS absorption spectrum, photoluminescence (PL) spectrum and Fourier transform infrared (FTIR) spectra of the product were also studied. The {120} side facet of the exposed surface of the resulting product with a large surface area (15.26 m2 g−1), effective crystallinity and increased number of surface active sites exhibited excellent photocatalytic efficiency with a higher rate constant (0.03254 min−1) for the degradation of methylene blue (MB) under visible light irradiation. The photocatalytic performance of as-synthesized WO3 octahedra was about 5.33 times greater than that of the bulk sample. The apparent excellent photocatalytic efficiency of the prepared sample can be attributed to large surface area and a highly reactive {120} facet of the exposed surface of the WO3 octahedra.