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It is critical to design bifunctional nonprecious electrocatalysts with low costs and high efficiency for hydrogen production. Conventional electrocatalysts, on the other hand, frequently exhibit s...

Herein, we report a facile hydrothermal synthesis of MnO2 nanoparticles anchored multi walled carbon nanotubes (MnO2@MWCNTs) as potential anode materials for lithium-ion (Li-ion) batteries. The prepared MnO2@MWCNTs were characterized by several techniques which confirmed the formation of MnO2 nanoparticles anchored MWCNTs. The X-ray diffraction and Raman-scattering analyses of the prepared material further revealed the effective synthesis of MnO2@MWCNTs. The fabricated Li-ion battery based on MnO2@MWCNTs exhibited a reversible capacity of ~823 mAhg−1 at a current density of 100 mAg−1 for the first cycle, and delivered a capacity of ~421 mAhg−1 for the 60 cycles. The coulombic efficiency was found to be ~100% which showed excellent reversible charge–discharge behavior. The outstanding performance of the MnO2@MWCNTs anode for the Li-ion battery can be attributed to the distinctive morphology of the MnO2 nanoparticles anchored MWCNTs that facilitated the fast transport of lithium ions and electrons and accommodated a broad volume change during the cycles of charge/discharge.

In this paper, pure SnO2 and Ce-doped SnO2 nanosheets were synthesized through a facile hydrothermal method. The synthesized materials were characterized by different techniques for their physico-chemical properties. The XRD data indicated the characteristic tetragonal rutile crystal phase for SnO2. Ce doping was ascertained by the presence of the diffraction peaks of CeO2 in all the doped samples of the SnO2 nanosheets. FESEM images revealed highly rough surfaces as well as the agglomeration of a large number of small nanoparticles of multiple shapes to form nanosheets like morphologies for pure SnO2 and Ce-doped SnO2. Electrochemical techniques like cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry were applied to demonstrate the electrochemical performances of the pure SnO2 and Ce-doped SnO2 nanosheets/Nafion-modified glassy carbon electrode (GCE). The 3% Ce-doped SnO2 nanosheet/Nafion-modified GCE showed a remarkable sensitivity of 0.9986 μA μM−1 cm−2 over a linear dynamic range of 0.5–20.3 µM. The corresponding linear regression equation was Ip (μA) = 0.0709 [2-nitroaniline (μM)] + 0.1385 with R2 = 0.99325. The LOD of the modified sensor was found to be 6.3 ± 0.1 nM at the signal-to-noise ratio of S/N = 3. The newly developed sensor electrode exhibited good selectivity toward 2-nitroaniline in the presence of common interfering species. Fabrication and characterization of highly sensitive and selective 2-nitroaniline chemical sensor based on cerium-doped tin oxide nanosheets/Nafion-modified glassy carbon electrode.

Ethanol is one of the volatile organic compounds as well as organic pollutants that is essentially to be monitored using high response sensors. Semiconducting metal oxide nanostructures can be the potential sensor material for high-performance ethanol sensing application. Herein, we present the fabrication and characterization of highly sensitive and selective ethanol gas sensor based on flower-shaped CuO composed of thin nanoplates synthesized by facile hydrothermal process. The prepared flower-shaped CuO was examined by various techniques viz FESEM, XRD, EDS, elemental mapping, HRTEM, SAED, UV-visible spectroscopy, FTIR spectroscopy, and Raman spectroscopy, which confirmed the high-density growth, monoclinic crystal structure, and optical band gap of ~2.5 eV. The fabricated resistive sensor device based on flower-shaped CuO, at optimum experimental conditions, i.e., 250 °C, 100 ppm ethanol concentration, exhibited a high sensing response of 241%, while, at 10 ppm of ethanol concentration, the response was observed to be 5%. The transient responses as well as the stability of the sensor were analyzed and reported here. The selectivity of CuO sensor device was studied for NO2, CO2, CO, and CH4 gases and remarkably it was seen that the developed gas sensor devices demonstrated outstanding selectivity toward ethanol gas. Finally, the gas response mechanism of the fabricated resistive ethanol gas sensor was explained on the basis of the ionosorption model.

In this paper, star-fruit-shaped CuO microstructures were hydrothermally synthesized and subsequently characterized through different techniques to understand morphological, compositional, structural, crystal, optical and vibrational properties. The formation of star-fruit-shaped structures along with some polygonal and spherical nanostructures was confirmed by FESEM analysis. XRD data and Raman spectrum confirmed the monoclinic tenorite crystalline phase of the CuO with crystal size 17.61 nm. Star-fruit-shaped CuO microstructures were examined for ethanol gas sensing behavior at various operating temperatures and concentrations. The gas response of 135% was observed at the optimal temperature of 225 °C. Due to excellent selectivity, stability and re-usability, the as-fabricated sensor based on star-fruit-shaped CuO micro-structures may be explored for future toxic gas sensor applications.

Root like structured Ni-doped zinc oxide [Zn(1-x)NixO (x = 0.09)] thin films were deposited on a non-conducting glass substrate by indigenously developed spray pyrolysis system at optimized substrate hotness of 573±5 K. Thus obtained Ni-doped ZnO thin films were characterized by UV-visible spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Atomic Force Microscopy (AFM). XRD result revealed that Ni-doped ZnO has a polycrystalline nature with a hexagonal wurtzite structure. For pure ZnO and Ni-doped ZnO thin films, the particle sizes were 60.9 and 53.3 nm while lattice strain values were 1.56×10−3 and 1.14×10−3, respectively. The film surface showed characteristic root-like structure as observed by the SEM. It was observed that the Ni-doped ZnO thin films were grown in high density along with more extent of branching as compared to pure ZnO thin films but retained the root-like morphologies, however, the branches were more-thinner and of shorter lengths. AFM analysis showed that the surface grains of the Ni-doped samples are homogeneous with less RMS roughness values compared with the undoped ZnO samples. The photocatalytic activity of the prepared thin films was evaluated by the degradation of methyl orange (MO) dye under UV light irradiation. Pure ZnO and Ni-doped ZnO thin films took 150 min and 100 min to degrade about 60% MO dye, respectively.

2D SnO2 disks with excellent purity and crystallinity were synthesized through a low cost, facile hydrothermal process and were characterized in terms of their morphological, structural, optical and electrochemical properties. The 2D disk-like morphology of synthesized SnO2 presented the average thickness of ∼1 μm and possessed the typical rutile tetragonal phase for the SnO2 with preferred growth along (100) plane. As-synthesized SnO2 disks were used for the fabrication of gas sensors for reducing gases like H2, CO, and C3H8. With the optimized temperature at 400 °C, the as-synthesized SnO2 electrode expressed the gas responses of 14.7, 9.3 and 8.1 for H2, CO, and C3H8, respectively. Contrary, the reasonable response times of 4 s, 3 s, and 8 s and the recovery times of 331 s, 201 s, and 252 s were recorded for H2, CO, and C3H8 gases, respectively. The DFT studies conducted herein suggest that the adsorbed oxygenated species act as a primary redox mediator for gas sensing reaction between reductive gases like H2, CO and C3H8, and SnO2 sensor. From DFT analysis, a very low heat of adsorption (≤0.2 eV) estimated which suggested the physisorption of the H2 molecules on the surface of the sensing material (i.e. SnO2). In contrast, the deposited oxygen atom forms strong chemical bonds with O2c and O3c sites. The oxygen atom bonded to O2c site control the conductivity of the sensor better than the O3c sites.

Photocatalysts provide excellent potential for the full removal of organic chemical pollutants as an environmentally friendly technology. It has been noted that under UV-visible light irradiation, nanostructured semiconductor metal oxides photocatalysts can degrade different organic pollutants. The Sn6SiO8/rGO nanocomposite was synthesized by a hydrothermal method. The Sn6SiO8 nanoparticles hexagonal phase was confirmed by XRD and functional groups were analyzed by FT-IR spectroscopy. The bandgap of Sn6SiO8 nanoparticles (NPs) and Sn6SiO8/GO composites were found to be 2.7 eV and 2.5 eV, respectively. SEM images of samples showed that the flakes like morphology. This Sn6SiO8/rGO nanocomposite was testing for photocatalytic dye degradation of MG under visible light illumination and excellent response for the catalysts. The enhancement of photocatalytic performance was mainly attributed to the increased light absorption, charge separation efficiency and specific surface area, proved by UV-vis DRS. Further, the radical trapping experiments revealed that holes (h+) and superoxide radicals (·O−2) were the main active species for the degradation of MG, and a possible photocatalytic mechanism was discussed.

Herein, we report the facile synthesis, characterization and visible-light-driven photocatalytic degradation of perforated curly Zn0.1Ni0.9O nanosheets synthesized by hydrothermal process. The X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies confirmed the cubic phase crystalline structure and growth of high density perforated curly Zn0.1Ni0.9O nanosheets, respectively. As a photocatalyst, using methylene blue (MB) as model pollutant, the synthesized nanosheets demonstrated a high degradation efficiency of ~76% in 60 min under visible light irradiation. The observed results suggest that the synthesized Zn0.1Ni0.9O nanosheets are attractive photocatalysts for the degradation of toxic organic waste in the water under visible light.

Herein, NOx, i.e., nitric oxide (NO) and nitrogen dioxide (NO2), gas sensors were fabricated using iron (Fe)-doped ZnO nanoparticles prepared via the facile hydrothermal process. The synthesized Fe-doped ZnO nanoparticles were analyzed through several techniques that revealed the well-crystallinity and dense growth of nanoparticles with the typical diameters of 25 ± 5 nm. The synthesized nanoparticles were utilized as a prospective material for the fabrication of NOx gas sensors operating at different temperatures, i.e., 350 °C, 400 °C, and 450 °C. The detailed sensing performances revealed that the optimum and most suitable sensing temperature for the fabricated sensors is 400 °C. In presence of 10 ppm NO gas, the fabricated sensor exhibited the highest gas response of 1.35 with a response (tresponse) and recovery (trecovery) time of 44 s and 402 s, respectively. Similarly, the fabricated NO2 gas sensor, in presence of 10 ppm gas shows the highest gas response of 1.33 with a response and recovery times of 50 s and 281 s, respectively. The presented results demonstrate that Fe-doped ZnO nanomaterials are capable to fabricate efficient NOx gas sensors.

In this paper, Ag doped MnO2-CNT nanocomposite was fabricated by using simple co-precipitation route. The synthesized nanocomposite was employed as adsorbent for elimination of Acridine Orange dye. The structural analysis of as synthesized Ag doped MnO2-CNT nanocomposite confirms the presence of (111) plane of Ag, (104) of carbon and (110) plane of MnO2. Processing of operational variable parameters such as, pH, adsorbent dose, and initial dye concentration with respect to contact time on adsorption of Acridine Orange was optimized and evaluated using Response Surface Methodology. The fit of the predictive model for the removal of dye was in good agreement with the experimental value. Isotherm data was modelled by means of Langmuir, Freundlich, Temkin and Dubinin- Radushkevich isotherm. Langmuir isotherm offered the best fit to experimental data proposing homogeneous dispersion of adsorption sites. Furthermore, the suitability of the adsorbent was also investigated by fitting the adsorption data with pseudo-second-order kinetic model. The recuperation and reusability of the adsorbent and adsorbate has made this process inexpensive and appropriate for large scale applications.

Herein, we report the effect of synthesis temperature on the morphologies, optical and electronic properties of magnesium oxide (MgO) nanostructures. The MgO nanostructures were synthesized at different temperatures, i.e., 100 °C, 300 °C, and 600 °C by simple chemical reaction process and their morphology, particle size, optical, and electrical properties were examined by different techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and UV-Vis. spectroscopy. The morphological investigations revealed that various morphologies of MgO nanostructures, i.e., nanoparticles, nanosheet networks, and nanoneedles were synthesized at 100 °C, 300 °C, and 600 °C. The XRD results confirmed that with increasing the synthesis temperature, the crystallinity of the synthesized nanostructures increases. Further, the dielectric properties and AC conductivity at various frequencies for MgO nanostructures were studied which revealed that the dielectric losses decrease with increase in frequency and temperature. In addition, the observed band gap decreases from 4.89 eV to 4.438 eV (100 °C to 600 °C) representing its increase in the conductivity.

Herein, we report the facile microwave-assisted synthesis, characterization and photocatalytic degradation applications of Bismuth ferrite heterostructures composed of interconnected nanosheets (BHNs). The synthesized materials were subjected to several analytical studies such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy and UV-visible spectroscopy in order to examine the morphological, structural, optical and photo catalytic properties. The structural and morphological characterizations confirmed the rhombohedral perovskite crystal structure and the formation of heterostructures composed of interconnected nanosheets for the synthesized material. The compositional characterization revealed that the synthesized material is bismuth ferrite with high purity. The BHNs were further used as efficient photocatalyst for the photocatalytic degradation of highly hazardous pollutant methyl orange under sunlight irradiation. The sunlight driven photocatalytic experiments revealed ~86% photodegradation of methyl orange dye in 150 min. The presented work revealed that the synthesized BHNs are excellent material for the photocatalytic degradation of various organic contaminants and hazardous pollutants.

Herein, we report the synthesis and analysis of fern shaped La2O3 nanostructures as potential scaffolds for efficient hydroquinone chemical sensing application. A facile, low-cost hydrothermal method was applied for the synthesis of 3D fern shaped La2O3 nanostructures. Several techniques were employed to characterize the synthesized La2O3 nanostructures. XRD analysis confirmed the hexagonal phase for the La2O3 nanostructures with an average crystallite size of 35.18 nm. FESEM and TEM analysis established the 3D fern shaped structures for La2O3 nanostructures with dendritic arms of different lengths alongside triangular-ovate outlines. Purity, composition and vibrational features were confirmed by EDS, FTIR and Raman spectroscopic studies. The fabricated 3D fern shaped La2O3 nanostructures modified glassy carbon electrode (GCE) showed remarkable electron mediating properties towards hydroquinone even at very low analyte concentrations. The linear dynamic range (LDR), experimental limit of detection (LOD) and sensitivity for 3D fern shaped La2O3 nanostructures modified GCE in phosphate buffer solution (PBS) were found to be 0.0781–0.625 mM, 0.0781 mM and 463.3 μA mM−1cm−2, respectively. Finally, a mechanism was also proposed for the electrochemical sensing of the hydroquinone. The presented work thus, confirms that the 3D fern shaped La2O3 nanostructures may be the future potential candidates for fabricating efficient and reproducible electrochemical sensors.

We demonstrate the preparation of nanostructures cobalt oxide/reduced graphene oxide (Co3O4/rGO) nanocomposites by a simple one-step cost-effective hydrothermal technique for possible electrode materials in supercapacitor application. The X-ray diffraction patterns were employed to confirm the nanocomposite crystal system of Co3O4/rGO by demonstrating the existence of normal cubic spinel structure of Co3O4 in the matrix of Co3O4/rGO nanocomposite. FTIR and FT-Raman studies manifested the structural behaviour and quality of prepared Co3O4/rGO nanocomposite. The optical properties of the nanocomposite Co3O4/rGO have been investigated by UV absorption spectra. The SEM/TEM images showed that the Co3O4 nanoparticles in the Co3O4/rGO nanocomposites were covered over the surface of the rGO sheets. The electrical properties were analyzed in terms of real and imaginary permittivity, dielectric loss and AC conductivity. The electrocatalytic activities of synthesized Co3O4/rGO nanocomposites were determined by cyclic voltammetry and charge-discharge cycle to evaluate the supercapacitive performance. The specific capacitance of 754 Fg-1 was recorded for Co3O4/rGO nanocomposite based electrode in three electrode cell system. The electrode material exhibited an acceptable capability and excellent long-term cyclic stability by maintaining 96% after 1000 continuous cycles. These results showed that the prepared sample could be an ideal candidate for high-energy application as electrode materials. The synthesized Co3O4/rGO nanocomposite is a versatile material and can be used in various application such as fuel cells, electrochemical sensors, gas sensors, solar cells, and photocatalysis.

Herein, α-Fe2O3 nanocubes were synthesized, characterized and employed as functional and promising material for the development of ethanol gas sensor. Facile hydrothermal process was used to synthesized the nanocubes and characterized by several techniques which confirmed the large-quantity synthesis, wellcrystallinity with rhombohedral structure of α-Fe2O3. The Raman-scattering spectrum of the synthesized nanocubes exhibited several Raman-active modes which further confirmed the formation of pure α-Fe2O3. As a functional material, the synthesized α-Fe2O3 nanocubes were used as electrode material to fabricate ethanol gas sensor which was tested at various working temperatures, i.e., 300 °C, 400 °C and 450 °C which revealed that the 400 °C was the optimal working temperature. Thus, at 400 °C working temperature, in presence of 100 ppm ethanol gas, the fabricated sensor exhibited highest gas response of 1.69 with response time < 1 s and recovery time of 1485 s.

Vanadium dioxide (VO2(M)) is a first order reversible thermochromic material which changes its phase at particular temperature and thus can be used as a thermochromic smart material for window coating. Similarly, the cerium dioxide (CeO2) is a well-known photo catalyst which can be applied on vanadium dioxide for self-cleaning. This paper reports a successful direct synthesis and detailed characterizations of core-shell VO2(M)@CeO2 spherical nanoparticles. In the core-shell nanoparticles, the vanadium dioxide core exhibits a solar light modulation property while cerium dioxide shell shows dye degradation through a facile photocatalytic process. Addition of ceria facilitates the VO2 (B) to VO2 (M) transformation and also improves its optical properties. With reduced transition temperature, the thermal stability was enhanced due to core –shell structure. To the extent of our knowledge, the synthesis of core-shell VO2@CeO2 nanoparticles is reported for the first time. The synthesized nanoparticles exhibited improved thermochromic and photocatalytic properties.

Herein, we report the enhanced solar light-mediated photocatalytic degradation of brilliant green dye using BiPO4 nanospindles and MoS2/BiPO4 nanorods synthesized by facile hydrothermal process. The synthesized nanomaterials were examined by various techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy (TEM) attached with energy dispersive X-ray spectroscopy, Brunauer–Emmett–Teller, and pore size distribution analysis. The detailed characterizations revealed that after the introduction of MoS2, the crystalline phase transformation from hexagonal to monoclinic was observed for BiPO4. The TEM images clearly confirmed that BiPO4 possessed nanospindles and MoS2/BiPO4 exhibited nanorod-shaped morphologies. The photocatalytic activity of synthesized MoS2/BiPO4 nanorod heterojunction was explored for the degradation of brilliant green (BG) dye under solar light irradiation. Interestingly, approximate 80% degradation of BG was observed under solar light in 70 min using MoS2/BiPO4 nanorods as photocatalyst. As an efficient photocatalyst, the synthesized MoS2/BiPO4 nanorod heterojunction exhibited enhanced photocatalytic efficiency as compared to pure BiPO4 nanospindles, commercially available TiO2PC-50 and TiO2 PC-500 under solar light. The high photocatalytic activity of MoS2/BiPO4 nanorod heterojunction could be related to the amended visible light-harvesting tendency, effective charge separation, and facile transportation of photogenerated e−/h+ pairs at the heterojunction interface.

Herein, we report the synthesis, characterization and picric acid chemical sensing application of samarium (Sm) doped ZnO nanorods. The Sm-doped ZnO nanorods were synthesized by facile hydrothermal process and characterized using various analytical methods which confirmed the large-scale synthesis and wurtzite hexagonal crystal structure for the synthesized nanorods. The doping of Sm ions in the lattices of the synthesized nanorods was evaluated by the energy dispersive X-ray spectroscopy (EDS). The synthesized Sm-doped ZnO nanorods were used as potential scaffold to fabricate high sensitive and reproducible picric acid chemical sensor based on I–V technique. The fabricated picric acid chemical sensor based on Sm-doped ZnO nanorods exhibited a high sensitivity of 213.9 mA mM−1 cm−2 with the limit of detection of ∼0.228 mM and correlation coefficient of R═0.9889. The obtained results revealed that the facile grown Sm-doped ZnO nanorods can efficiently be used to fabricate high sensitive and reproducible chemical sensors.

Copper selenide and copper telluride nanostructures were synthesized using Bovine serum albumin, for the first time, via a facile hydrothermal method. The involvement of different precursors was proposed through a probable reaction mechanism. Moreover, the structural and optical properties of the prepared Cu(2−x)Se and Cu(2−x)Te nanostructures were investigated. The average sizes of the synthesized copper selenide nanoparticles were in the range of 87 ± 24 nm. Variation in size and shape for copper telluride nanostructures gave round shape nanoparticles as well as rods in micro and nano size and average size for small and large round shape nanoparticles were 52 ± 16 nm and 216 ± 27 nm, respectively. More precisely, size-strain plot and the Williamson-Hall analysis methods were adopted to determine the lattice strain and crystalline sizes of the synthesized nanoparticles. The optical band gap energy of prepared nanoparticles estimated from the UV–Vis spectroscopy was 2.95 and 2.32 eV for Cu(2−x)Se and Cu(2−x)Te nanoparticles, indicating quantum confinement effect due to the deviation from bulk materials to the nanoscale. Moreover, the band gap decreased with enhancement of BSA concentration which suggest that the usage of BSA content is important factor and must be optimized for obtaining desired optical band gap. The electrical conductivity for copper selenide and copper telluride was found as 0.048 − 0.064 × 105 S cm−1 and 0.011 − 0.017 × 106 S cm−1 respectively.

Silver embedded banana peel biochar (Ag-BBc) composite was tailored effectively by green synthetic route. Azadirachta indica leaf extract was employed for preparation of Ag nanoparticles as reducing agent and biochar was derived from the of banana peel via pyrolysis. The multi-functionality of the fabricated nanocomposite was investigated through its application towards energy storage and environmental remediation. The prepared composite was characterized in detail by various analytical techniques and the electro-chemical aspects were examined by cyclic-voltammetry and galvanostatic charge-discharge methods. The improved specific capacitance of Ag-BBc composite was measured as 655 Fg-1 in 1 M Na2SO4 at a current density of 0.35 Ag-1. The Ag-BBc modified electrode exhibited an excellent cyclic stability of 79.3% after 5000 charge/discharge cycles and displayed high energy and power density of 40 Wh/kg and 490 Wkg−1 respectively, at 1 Ag-1. Furthermore, Ag-BBc composite was used for the ultrasonic assisted adsorption of Congo Red dye with appreciable adsorption efficacy of ∼98% within 5 min of contact time. Langmuir and Freundlich isotherms were considered to describe the equilibrium of dye using ultrasonic assisted adsorption process.

Developing biomaterials based on the natural biomacromolecule silk sericin from Bombyx mori cocoon is of great interest for biomedical application. Dialdehyde carboxymethyl cellulose (DCMC) is derived from periodate oxidation of carboxy- methyl cellulose. Here, we developed a novel strategy of cross-linking of sericin with DCMC via the Schiff's base reaction. Fourier transform infrared spectroscopy and scanning electron microscopy indicated the formation of Schiff's base via the blending of sericin and DCMC. The mechanical properties tests suggested the covalent cross-linking effectively enhanced the tensile strength of sericin. The swelling test and water contact angle indicated the DCMC/SS film had excellent hydrophilicity, swellability. Additionally, we demonstrated the DCMC/SS film had excellent blood compatibility, cytocompatibility and promoting cell proliferation activity by the hemolysis ratio analysis, cell adhesion, cells viability and proliferation assays. The prepared DCMC/SS film has shown great promise in biomedical applications such as wound dressing, artificial skin and tissue engineering.

Herein, we report the successful synthesis of BiF3 octahedrons via facile hydrothermal process as potential solar light active catalyst for the photocatalytic degradation of Rhodamine B (RhB) dye in aqueous phase. The synthesized BiF3 octahedrons were characterized by several techniques such as X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), Fourier transform infrared (FT-IR) spectroscopy, UV-diffuse reflectance spectroscopy (UV-DRS), photoluminescence (PL) spectroscopy, thermogravimetric analysis (TGA) and Brunauer-Emmett-Teller (BET) techniques in order to observe the structural, morphological, optical and luminescence properties. The synthesized octahedrons possess the high density growth, pure and well-crystalline with cubic phase structure and band gap of 3.98 eV. As a potential solar light active photocatalyst , the synthesized BiF 3octahedrons exhibited ˜95.7% degradation of RhB in 50 min. The effect of different process parameters such as pH and catalyst dose on the degradation of RhB was also explored. Interestingly, the synthesized BiF3 octahedrons demonstrated better photocatalytic performance compared to several commercially available photocatalysts such as TiO2 (PC-500), SnO2 and ZnS. Further, it was observed that the degradation of RhB over the prepared BiF3 octahedrons obeyed the pseudo first-order reaction kinetics with rate constant of 0.06393 min−1. The scavenger experiments verified the role of h+, e, O2 , OH and OHs in the photocatalytic degradation process and a plausible photocatalytic mechanism has also been proposed.

Reduced graphene oxide modified by hyperbranched polyamine-ester (RGO-HBPE) liquids was successfully fabricated through the surface chemical engineering and tested for serving as a solvent-free novel lubricant. Structural characterization, dispersibility and rheology behavior of the lubricant and the related frication performance on steel plate were investigated thoroughly. The results manifest that the RGO-HBPE exhibited good dispersity in distilled water and liquid behavior without any solvent at ambient temperature. And this RGO-HBPE liquids could be directly introduced onto the surface of steel plate as lubricants without any additional base oil. Tribological results and the proposed lubricating mechanism of RGO-HBPE imply that the fluidity of RGO-HBPE is favorable for lubrication and is crucial to reduce the friction coefficient. The spontaneous flow of RGO-HBPE provide a spreading effect to form the lubricating film. The specific spreading effect of RGO-HBPE and the synergistic lubricating effect between HBPE and graphene demonstrate that RGO-HBPE could be directly used as promising candidates for lubricants in nowadays moving machines.

Herein, we have developed a novel sensing electrode to detect the eco-toxic 4-nitrophenol (4-NP). Ag-doped-ZnO nanoflowers were synthesized by facile hydrothermal method and examined by several characterization techniques in order to understand the morphology, crystal structure, composition, and surface properties. Morphological results were confirmed by the formation of Ag-doped ZnO nanoflowers decorated with nanosheets. Ag-doped ZnO/glassy carbon electrode (GCE) electrode-material-matrix was used for electrochemical sensing of toxic 4-NP. Under optimized conditions, Ag-doped ZnO/GCE modified electrode exhibits high-sensitivity and selectivity compared to the bare GCE electrode. The Ag-doped ZnO/GCE modified electrode exhibits high electrocatalytic oxidation towards 4-NP. Anodic peak current of 4-NP is increased linearly by increasing the concentration of nitrophenol. Additionally, Ag-doped ZnO/GCE shows a wide range of sensitivity from 10 µM to 500 µM, and a linear calibration plot with a good detection limit of 3 µM (S/N = 3). The proposed Ag-doped ZnO/GCE modified electrode showed high sensing stability. In addition, the oxidation mechanism was studied. The obtained results revealed that the Ag-ZnO/GCE electrode could be the promising sensing electrode for 4-NP sensing.

Herein, we report a chemi-resistive sensing method for the detection of formaldehyde (HCHO) gas. For this, α-MnO2 nanowires were synthesized hydrothermally and examined for ascertaining their chemical composition, crystal phase, morphology, purity, and vibrational properties. The XRD pattern confirmed the high crystallinity and purity of the α-MnO2 nanowires. FESEM images confirmed a random orientation and smooth-surfaced wire-shaped morphologies for as-synthesized α-MnO2 nanowires. Further, the synthesized nanowires with rounded tips had a uniform diameter throughout the length of the nanowires. The average diameter of the α-MnO2 nanowires was found to be 62.18 nm and the average length was ~2.0 μm. Further, at an optimized temperature of 300 °C, the fabricated HCHO sensor based on α-MnO2 nanowires demonstrated gas response, response, and recovery times of 19.37, 18, and 30 s, respectively.

In the present research work, 2D-Porous NiO decorated graphene nanocomposite was synthesized by hydrothermal method to monitored the concentration of epinephrine (EPI). The morphology (SEM and TEM) results confirmed 2D-Porous NiO nanoparticles firmly attached over graphene nanosheets. FTIR and XPS analysis confirmed the formation of nickel oxide formation and complete reduction of GO to rGO. The electrochemical activity of the proposed NiO-rGO/GCE modified electrode on epinephrine was analyzed by simple cyclic voltammetry technique. The proposed low cost NiO-rGO/GCE modified electrode showed excellent catalytic activity over GCE and rGO/GCE electrodes. Due to its high conductivity and charge transfer ability of the NiO-rGO/GCE modified electrode exhibited high sensitivity of EPI at optimized conditions. The anodic peak current of the EPI linearly increases with increasing the concertation of EPI. A wide linear range (50 μM–1000 μM) was achieved with high correlation coefficient (R2 = 0.9986) and the limit of detection (LOD) of NiO-rGO/GCE modified electrode was calculated to be 10 μM. NiO-rGO/GCE electrode showed good stability and repeatability towards the EPI oxidation. Mainly, the proposed NiO-rGO/GCE modified electrode showed good sensitivity of EPI in the human biological fluid with high recovery percentage. The low cost, NiO-rGO/GCE electrode could be the promising sensor electrode for the detection of Epinephrine in the real samples.

This paper reports synthesis, properties and gas sensing applications of ZnO nanoflowers and CdO–ZnO nanorices prepared by hydrothermal process. The morphological characterizations confirmed the formation of well-defined nanoflowers and nanorices structures for ZnO and CdO–ZnO nanomaterials, respectively. The structural properties revealed the wurtzite hexagonal phase of the synthesized materials. The sensor devices based on ZnO nanoflowers and CdO–ZnO nanorices were fabricated and tested towards various gases including ethanol, methanol, ammonia, carbon monoxide, methane and formaldehyde. The fabricated gas sensor based on CdO–ZnO nanorices exhibited a high response (34.5) towards 300 ppm formaldehyde gas at 350 °C compared to ZnO nanoflowers (14.5) under the same experimental conditions. The response and recovery times for ZnO nanoflowers-based sensor were~9.8 s and ~6 s while for CdO–ZnO based sensor, these were ~10s and ~6s, respectively. A rapid response (34.5) for CdO–ZnO nanorices based formaldehyde gas sensor was observed as compared to other gases such as ammonia (12.3), methanol (16.5), ethanol (20), carbon monoxide (16.3) and methane (12.4), which confirm the high-selectivity towards formaldehyde gas. Finally, a plausible formaldehyde gas sensing mechanism is proposed.

Herein, for the first time, the growth of ZnO nanorods directly on aluminum (Al) substrate via a low temperature (80 &deg, C) wet chemical method, and used as binder-free electrode for supercapacitors were reported. XRD pattern and HRTEM images showed that high crystalline nanorods grown on Al substrate with c-axis orientation. Morphological studies revealed that the nanorods possessed well defined hexagon phase with length and diameter of ~2 &micro, m and 100&ndash, 180 nm, respectively. Raman spectrum of ZnO nanorods showed that the characteristic E2H mode corresponds to the vibration associated with the oxygen atoms of ZnO. The optical properties of ZnO nanorods studied using Room-temperature PL spectra revealed a near-band-edge (NBE) peak at ~388 nm emission and deep level (DLE) at ~507 nm. Electrochemical measurements showed that ZnO nanorods on Al substrate exhibited remarkably enhanced performance as electrode for supercapacitors with a value of specific capacitance of 394 F g&minus, 1 measured with scan rate of 20 mV s&minus, 1. This unique nanorods structures also exhibited excellent stability of &gt, 98% capacitance retention for 1000 cycles that were measured at 1A g&minus, 1. The presented easy and cost-effective method might open up the possibility for the mass production of binder-free electrodes for efficient electrochemical energy storage devices.

Herein, we report the synthesis, characterization and enhanced adsorption studies of porous octahedral shaped Cu-BTC (copper benzene-1,3,5-tricarboxylate) metal organic frameworks (MOFs). The Cu-BTC MOFs were synthesized by facile hydrothermal process and characterized by various techniques in order to examine the structural, morphological, thermal and adsorption-desorption properties. The synthesized Cu-BTC MOFs were used as potential scaffold for the adsorption of highly toxic azo dye, i.e. methylene blue (MB). Detailed adsorption studies on the effect of initial pH, concentration, reaction time and temperature on adsorption of MB were analysed and it was observed that the removal of MB followed pseudo-2nd order kinetic model. Freundlich model fitted well as compared to Langmuir model with R2 of 0.975 and thereby signifying a multilayer adsorption of MB on the surface of Cu-BTC MOFs. The observed maximal adsorption capacity for MB removal (200 mg/L) was ∼101.21 mg/g using Langmuir isotherm. The Cu-BTC MOFs exhibited 42.3 mg/g adsorption capacity after fourth cycle of MB dye adsorption. These features exhibited that Cu-BTC MOF have potential for the adsorption of MB and can efficiently be used to treat wastewater.

Molybdenum disulfide (MoS2) is an extremely promising electrode material for supercapacitors due to its superior electrochemical performance and conductivity. In this study, polypyrrole (PPy) modified MoS2/Ni3S2 (MNS@PPy) assemblies grown directly on the Ni foam (NF) substrate are prepared by a facile hydrothermal route and a subsequent electrodeposition process. The as-obtained products show a specific capacitance of 845 C g−1 at 1 A g−1 with outstanding cycling stability after 10 000 cycles. Using the as-synthesized products as positive materials, an assembled hybrid capacitor delivers an energy density of 280.5 W h kg−1 at a power density of 2845 W kg−1, demonstrating its promising application in portable micro-/nanoscale energy storage devices.

Spindle-like α-Fe2O3 and reduced graphene (rGO) composites have been synthesized by a simple hydrothermal method. The synthesized samples exhibit excellent electrochemical performance with high specific capacitance and good cycling life of about 87.5% reserved after 10,000 cycles. A solid-state asymmetric supercapacitor (ASC) with 1.5 V Voltage has been assembled using α-Fe2O3/rGO composite anode and the NiCo2O4 nanowires cathode. The ASCs exhibit outstanding capacitance performance with maximum energy density of 73 Wh kg−1 at the power density of 1357 W kg−1, and more than 219% capacitance retention after 10,000 cycles.

Poly(ethylene terephthalate) (PET) is a versatile engineering plastic which exhibits exceptional mechanical and thermal properties. Huge amounts of PET are consumed in various industries such as food packaging industry, textile industry, in the manufacturing of audio, video tapes and X-ray films and so on. But due to its substantial fraction by volume in water bodies and its high persistence to the atmospheric and biological agents, it could be considered as a hazard substance. Thereby chemical recycling of PET serves as a solution to solid waste problem as it transforms PET into its monomers via hydrolysis. Chemical recycling of post consumed waste PET bottles via alkaline hydrolysis is the main aim of this paper. Operating parameters such as reaction time and temperature were optimized for the conversion of PET into nanospindle-shaped terephthalic acid (TPA). Depolymerization of PET was carried out via alkaline hydrolysis by varying reaction time and temperature and maximum yield of 92% was obtained at 200 °C with reaction time of 25 minutes. The formed TPA nanospindles were further characterized in detail which exhibited high crystallinity, purity and fascinating thermal and surface properties.

Herein, we report a facile synthesis, characterization and dye sensitized solar cell (DSSC) application of flower-shaped ZnO nanostructures. The flower-shaped ZnO nanostructures were synthesized by low-temperature hydrothermal process and characterized in detail by several techniques. The detailed morphological studies confirmed that the flower-shaped structures are formed by the accumulation of several nanoneedles which are axially arranged through their bases in a special fashion that they made flower-like morphologies. The compositional, structural and optical characterizations revealed that the synthesized flowers possess high purity, well-crystallinity with the wurtzite hexagonal phase and good optical properties. The synthesized flower-shaped ZnO nanostructures were used as photoanode to fabricate DSSC which attained a reasonable solar to electrical conversion efficiency of ~1.1%, open-circuit current (VOC) of 0.611 V, short circuit current (JSC) of 3.53 mA/cm2 and fill factor (FF) of 0.51.

Herein, we report the facile synthesis of high-aspect ratio perforated Co3O4 nanowires derived from cobalt-carbonate-hydroxide (Co(CO3)0.5(OH) 0.11H2O) nanowires. The Co(CO3)0.5(OH) 0.11H2O nanowires were synthesized by simple hydrothermal process at 120 °C while annealing of such nanowires at 400 °C leads the formation of perforated Co3O4 nanowires. The prepared nanowires were characterized by several techniques which confirmed the high aspect ratio and well-crystallinity for the synthesized nanowires. For application point of view, the prepared perforated Co3O4 nanowires were used as efficient electrode material to fabricate highly sensitive and selective hydrazine chemical sensor. The electrochemical impedance spectroscopy (EIS) technique was employed to confirm the successful modification of the electrode. The key parameters of chemical sensor, such as detection limit, sensitivity, and linear range, have been systematically explored. The fabricated hydrazine sensor displayed a rather low detection limit of 4.52 μM (S/N = 3), a good sensitivity of 25.70 μA · mM-1, and a wide linear range of 16.97-358.34 μM.

In this paper, we report the synthesis, characterization and ethanol sensing applications of CuO nanoparticles. The CuO nanoparticles were prepared by a facile, low-temperature hydrothermal method and characterized in detail in terms of their structural, morphological, compositional and crystalline properties, through different characterization techniques including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) attached with energy dispersive spectroscopy (EDS), and Fourier transform infrared (FTIR) spectroscopy. The detailed studies revealed that the synthesized CuO nanoparticles were well-crystalline and possessed monoclinic crystal structure. The synthesized CuO nanoparticles were utilized for the fabrication of highly sensitive ethanol gas sensor. At an optimized temperature of 320 °C, high sensitivity (Ra/Rg) of 39.29 was observed for 200 ppm of ethanol gas. Additionally, very low response (τres = 14 s) and recovery (τrec = 30 s) times were observed for 100 ppm of ethanol.

Herein, we report a hydrothermal process to synthesize well-defined and crystalline composite CdO-ZnO hexagonal nanocones and their efficient utilizations as electrode materials to fabricate photovoltaic and sensor devices. The synthesized material was characterized in detail using several techniques which confirmed its hexagonal nanocones-shaped morphologies with an average diameter of ~ 60–80 nm, well-crystallinity and purity. The sensing behavior of synthesized CdO-ZnO hexagonal nanocones were examined by investigating the I-V characteristics of various nitroaniline concentrations in phosphate buffer solution (PBS). The synthesized CdO-ZnO hexagonal nanocones electrode showed a rapid response with high sensitivity of ~ 129.82 μA mM−1 cm−2 toward the nitroaniline chemical. As a photoanode, the fabricated dye sensitized solar cell (DSSC) attained reasonable overall conversion efficiency of ~ 2.55% with high open circuit voltage (VOC) of ~ 0.810 V and fill factor (FF) of 0.64. The high VOC and FF could be attributed to the high series resistance, fast recombination rate and large charge transfer resistance of DSSC.

In this work, grain-like ɑ-Fe2O3 nanostructures are successfully obtained by a facile hydrothermal approach without using any templates. The morphology and microstructure of the as-synthesized products are characterized using scanning electron morphology (SEM) and transmission electron morphology (TEM). A possible growth mechanism of grain-like ɑ-Fe2O3 nanostructures is proposed by adjusting volume ratio of ethanol/water. The as-prepared ɑ-Fe2O3 products are used as the photocatalysts for the photocatalytic degradation of Congo red (CR) dyes. The result indicate that CR molecules can be degraded nearly completely (over 99%) after 24 min under visible light irradiation. The as-synthesized grain-like ɑ-Fe2O3 nanostructures might have potential application in eliminating organic pollutants in waste water.

This paper explains the preparation of SnO2-Sb2O3 composite catalyst by solid state reaction process, and posteriorly employs as an alternative and promising photocatalyst for Brilliant Green (BG) dye degradation under solar irradiation. SnO2 and Sb2O3 composite samples with varying proportions of SnO2 and Sb2O3 were created, with 2 to 5 w t% SnO2 added to the Sb2O3 sample. The synthesized samples were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDS) and UV-visible diffuse reflectance spectroscopy (DRS). The results showed that the 3% SnO2-Sb2O3 sample presented higher catalytic activity compared to the others, besides SnO2 and Sb2O3 alone, reaching ~90% of decolonization and ~87% of COD removal at 180 min. This remarkable photocatalytic activity may be associated to its favorable band gap energy. Kinetic data fitted well with pseudo-first-order kinetic model. Therefore, the SnO2-Sb2O3 composite prepared in this work can be considered as an effective photocatalyst for elimination of colored-contaminants, such as BG dye, from wastewater.

Herein, room-temperature NO2 gas sensor based on supramolecularly assembled isonicotinamide–graphene oxide nanocomposite (Iso-rGO) and Iso-rGO/Carbon felt (CF) electrode was prepared and studied. The morphology of the synthesized Iso-rGO nanocomposite was studied by field emission scanning electron microscopy (SEM), which revealed the uniform coating of isonicotinamide over the surface of the composite. Further studies confirmed the supramolecular functionalization assembly of isonicotinamide onto the surface of GO. The prepared nanocomposite was used as functional electrode material to fabricate room-temperature NO2 gas sensor. The fabricated electrode (Iso-rGO/CF) exhibited excellent reductive behavior of NO2 gas at room-temperature. The fabricated sensor exhibited a linear range from 1–30 ppm and a low detection limit (LOD) of 1 ppm towards NO2 gas. The NO2 sensitivity of the Iso-rGO/CF electrode is well correlated with online gas chromatography which demonstrate high sensitivity and good stability for more than 30 days. The observed results revealed that the proposed Iso-rGO/CF electrode could be a suitable sensor electrode for the sensitive detection of gaseous NO2 in the real samples.

Developing stable and highly efficient bifunctional electrocatalyst is very important for sustainable energy conversion technology. However, conventional electrocatalytic materials often show high overpotentials and low chemical activities. Conductive polymers anchored is thought an effective strategy to solve this problem. In this work, we report a kind of novel nanosheet arrays through a facile hydrothermal and subsequent electrodeposition process. The as-obtained CoNi2S4@PEDOT-150 products possess an overpotential of 270 mV for oxygen evolution reaction (OER) at 50 mA cm−2 and 90 mV for hydrogen evolution reaction (HER) at 10 mA cm−2 in 1.0 M KOH electrolyte. In addition, the electrode can be used as both anode and cathode for overall water splitting. It only requires a cell voltage of 1.75 V at 50 mA cm−2, which is superior to previous reports.

Herein, we report the facile synthesis, characterization and solar-light driven photocatalytic degradation of ultra-thin bismuth molybdenum oxide (Bi 2MoO6 ) nanosheets. The nanosheets were synthesized by hydrothermal process and characterized using several techniques such as powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), UV-diffusive reflectance spectroscopy (UV-DRS), transmission emission microscopy (TEM) and X-ray photon electron spectroscopy (XPS). The detailed morphological and structural studies confirmed the growth of ultra-thin Bi 2MoO6 nanosheets in large density with orthorhombic crystal structure. The calculated bandgap energy from Tauc’s plot for the synthesized nanosheets was found to be 2.73 eV, which shows maximum absorption toward higher wavelength. The XPS studies confirmed the successful formation Bi2MoO6 nanosheets. The synthesized material was used as efficient solar light driven photocatalyst for the photocatalytic degradation of Ofloxacin. The mineralization of ofloxacin was confirmed using total organic carbon (TOC) analysis and photocatalytic experiments were performed under optimized conditions. It was observed that TOC value decreased with increasing the irradiation time. Under optimized photocatalytic degradation conditions, the observed extent of degradation was found to be ∼ 71%. The observed results confirm that the synthesized Bi2MoO6 nanosheets are efficient and promising visible light responsive catalyst for the degradation of persistent organic pollutants.