An activated carbon/epoxy composite was synthesized in which waste mango leaves biomass was used as the carbon source. To create a sufficient amount of porosity in the biomass, a simple process of ...carbonization followed by its activation was used. The morphology and porosity of the activated carbon material were studied by SEM, TEM, and BET analysis, which confirmed the presence of macro- and mesopores in the material. The activated carbon/epoxy composite with 3 mm thickness gave the highest reflection loss (RL) of − 39.57 dB at 6.48 GHz. At a thickness of just 2 mm the maximum effective absorption bandwidth (RL < − 10 dB) of 2.14 GHz was achieved. This excellent microwave absorption performance was attributed to the porous and bowl-type structure, which resulted in large surface area, high impedance matching, and subsequent attenuation of microwaves by conduction losses, as well as interfacial and dipolar polarization processes. This study provides a porous activated carbon/epoxy composite that is lightweight and economical, and has a high structural stability for microwave absorption applications.
Graphical Abstract
An analog ensemble (AE) system is developed for realization of a set of several surface meteorological variables at three stations in the Senator Beck Basin (SBB), Colorado, U.S.A and at six stations ...in the north-west Himalaya (NWH), India. Quality of local scale surface weather analogs in the NWH and SBB is evaluated and compared with surface meteorological observations of different characteristics, a set of different surface meteorological variables and for different periods of a year. The Pearson Correlation Coefficients (CCs) and Root Mean Square Differences (RMSDs) of the maximum value in analog days (MMX), minimum value in analog days (MNX) and analog ensemble mean (ME) of a 10-member analog ensemble system and climatological mean (CM) of each surface meteorological variable for d0 lead time 0 h (0 h) from its observed values on d0, d1 (24 h), d2 (48 h) and d3 (72 h) are computed. This is done to examine the predictability potential of the AE system for simultaneous prediction of a set of several surface meteorological variables at local scale (specific site). The ME of each surface meteorological variable for d0 (constant forecasts of the AE system) exhibiting reasonable values of the CCs and RMSDs for d1, d2 and d3 will imply that the AE system exhibits high predictive potential and it is worth to develop the AE system in future for multiple forecast lead times (d1, d2 and d3) not just for d0. Moreover, the predictability potential of the AE system is studied in two climatologically and geographically distinct mountainous regions to seek its generalization capacity. The percentage of observations on various surface meteorological variables appearing as a member of the AE system and rank histograms for d0 are also used to evaluate the quality of local scale surface weather analogs. The results show that the AE system exhibits high predictability potential and generalisation capacity, and it performs reasonably well for a complete year. The RMSDs of the AE system for realisation of a set of several surface meteorological variables comparable and/or even marginally higher as compared to the Root Mean Square Errors (RMSEs) for their prediction with the help of various other types of weather forecasting models over the NWH and elsewhere suggest that the AE predictive system can be a handy tool for real-time prediction of multiple surface meteorological variables at local scale with least requirement of resources (human, data, computation and time).
Heavy snowfall during winter period (November to April) over the north-west Himalaya (NWH) generates many natural hazards. Time critical decisions primarily dependent on precipitation amount such as ...avalanche forecasting, flood forecasting, management of necessary services and supplies etc. demand real time weather forecasts, specially, quantitative precipitation forecasts (QPFs), at local scale during winter over the NWH. Two analog ensemble systems (AE1 system, AE2 system) for QPFs for varied forecast lead times are developed utilizing surface meteorological observations of 10 stations over the NWH. Performances of developed analog ensemble systems are evaluated and compared with performances of the climatological forecast models (CM1 model, CM2 model) for same forecast lead times for binary weather forecasts (precipitation day/no precipitation day) and QPFs at 10 stations over the NWH. The AE1 (AE2) system is found to perform better as compared to the CM1 (CM2) model for binary weather forecasts and QPFs at local scale over the NWH. Performance of the AE1 system for binary weather forecasts for shorter forecast lead times 0–15 h (0–15 h), 15–24 h, 24–39 h is found comparable to performance of the AE2 system for binary weather forecasts for longer forecast lead times 0–24 h, 24–48 h, 48–72 h. However, the Mean Absolute Errors (MAEs) and Root Mean Square Errors (RMSEs) for QPFs for shorter forecast lead times with the help of the AE1 system are found less as compared to the MAEs (RMSEs) for QPFs with the help of the AE2 system for longer forecast lead times. The AE1 system can provide real time QPFs based on recent surface meteorological observations for shorter lead times which can help in dynamic decision making for weather and avalanche forecasting over the NWH. However, QPFs with the help of the AE2 system can be useful for longer forecast lead times. Performances of the AE2 system and CM2 model are evaluated for binary weather forecasts and QPFs for a week period (7 days). The AE2 system is found to perform better as compared to the CM2 model for binary weather forecasts and QPFs for a week at local scale over the NWH. These results suggest that the AE2 system exhibits better consistency for QPFs as compared to the CM2 model for a week. The MAEs (RMSEs) for QPFs with the help of the AE1(AE2) system comparable to the MAEs (RMSEs) for QPFs with the help of other forecasting methods over the NWH (or elsewhere) suggest that the AE1(AE2) system exhibits good performance for real time QPFs at local scale over the NWH.
Here, we report the synthesis route of LaCoO
3
and nanocomposite with reduced graphene oxide (rGO) via solvothermal approach. The study of structural phase, phase purity, surface oxidation states, ...morphological, and electrochemical properties of synthesized materials is performed via various techniques: X-ray diffraction, high-resolution transmission electron microscope, scanning electron microscope, and Potentiostat SP-150, etc. It is evident from the various results obtained that the oxygen vacancy and nanocomposite enhance the electrical conductivity and ion/electron transfer leading to fast charge storage mechanism that, in turn, significantly enhances the electrochemical performance. The electrode designed of pristine LaCoO
3
delivered the specific capacitance of 225 F/g in comparison of nanocomposite LaCoO
3
/rGO electrode as 317 F/g at current density of 1.75 A/g and exhibited remarkable cycle life retention 95% and 96% after 1000 life charging discharging cycles, respectively. Furthermore, the designed asymmetric supercapacitor delivered the specific capacitance up to 38 F/g at current density of 2 A/g and held 76% retention after 5000 charging discharging cycles. The remarkable performance of nanocomposite materials indicates its propitious candidature for next-generation energy storage by overcoming the dependency on spinel-type structure material.
In this work we report, the structural, magnetic, and energy storage properties of double perovskite oxide Y
2
NiFeO
6
synthesized via wet chemical sol–gel process. The amorphous phase structure ...obtained at the synthesis temperature of 650 °C, turned to mixed cubic-hexagonal phase of Y
2
NiFeO
6
at 850 °C, and subsequently to thermally stable mixed cubic-orthorhombic phase at and above the temperature of 950 °C. The X-ray photoelectron spectra of thermally stable phase of Y
2
NiFeO
6
exhibited the presence of yttrium in Y
3+
state, nickel in Ni
2+
/Ni
3+
state and iron in Fe
3+
state. The Y
2
NiFeO
6
exhibited room temperature ferromagnetic behavior with Curie temperature at or above the room temperature. The highest specific capacitance achieved via cyclic voltammetry in three-electrode system was 74.10 F/g at the scan rate of 5 mV/s. It has remarkable specific capacitance retention of ~ 95% after 5000 chargingdischarging cycles at the current density of 6 A/g. The energy storage parameters i.e., energy density and power density were ~ 3.93 Wh/kg and ~ 810.03 Wkg
−1
, respectively at current density of 1 A g
−1
.
Graphic abstract
Chlorpyrifos (CPS) is a nerve poisoning organophosphate pesticide that inhibits acetylcholinesterase enzyme and badly impacts the nervous system and disruption of hormones in living beings. ...Heterostructured semiconductor photocatalysts show outstanding adsorption of organic contaminants for environmental remediation. In this study, we have synthesized CdS/NiS nanocomposite via hydrothermal method and use NCs as promising water splitting photocatalyst. The prepared NCs were characterized by X-ray diffraction, SEM–EDX, PL, UV–visible, and electrochemical impedance spectroscopy (EIS). X-ray diffraction (XRD) results indicate that as synthesized CdS/NiS nanocomposite is composed of hexagonal CdS and rhombohedral structured NiS. Energy-dispersive X-ray (EDX) gives the information of elemental composition, and the luminescence and band gap determination were done using PL and UV–visible spectroscopy. The CdS/NiS nanocomposite showed the enhanced optical properties as compared to CdS which confirmed the successful charge separation. The degradation of chlorpyrifos was therefore monitored to determine the efficiency of CdS/NiS hetrostructured photocatalyst and it was observed that 95.39% of CPS removal achieved within 110 min with 20 mg photocatalyst amount and 250 ppm concentration of pollutant. The electrochemical measurement indicated low charge transfer resistance (60.63 Ω) of CdS/NiS nanocomposite which infers high charge separation, also complemented by low emission peak intensity in PL spectrum. Scavenger tests are used to investigate the reactive species in photocatalytic reaction process. Further, the reusability of photocatalyst, when studied on fresh sample of CPS pesticide, the degradation efficiency decreased from 95.39 to 91.31%, indicating the efficient reusability of CdS/NiS nanocomposite. Compared to CdS, CdS/NiS nanocomposite exhibits the greater photocatalytic degradation rate under the irradiation of visible light.
In the present study, the solvothermal route is followed to synthesize cobalt doped nanomaterial LaNi
0.9
Co
0.1
O
3
and reduced graphene oxide reinforced LaNi
0.9
Co
0.1
O
3
nanocomposite. The ...electrochemical performance of symmetric and asymmetric energy storage devices is investigated by fabricating the electrodes using LaNi
0.9
Co
0.1
O
3
active materials and its composite with reduced graphene oxide. The structural phase of samples is associated with rhombohedral structure with agglomerated heterogeneous morphology. The nanocomposite showed the superlative result compared to cobalt doped electrode as evident by specific capacitance 436 F/g and 334 F/g at 1 A/g, respectively. The electrodes achieved 92 and 95% retention for LaNi
0.9
Co
0.1
O
3
and LaNi
0.9
Co
0.1
O
3
/rGO nanocomposites, respectively, for 1000 cycles. The asymmetric device shows significant improvement in specific capacitance of 86 F/g compared to the symmetric device of 38 F/g at current density 1 A/g. The cyclic test up to 3000 cycles was performed, where the LaNi
0.9
Co
0.1
O
3
electrode achieved 84% retention and the LaNi
0.9
Co
0.1
O
3
/rGO electrode sustained 86% retention. Overall nanocomposite material exhibits superior quality, which emerges as a promising candidate for future energy storage application.
Graphical abstract
The uniform nano-petaled CoFe
2
O
4
mesoporous flowers were prepared by facile hydrothermal technique. The material is characterized using Scanning Electron Microscope (SEM) and High-Resolution ...Transmission Electron Microscope (HRTEM) for analyzing morphological aspects. Surface area and porosity characteristics were measured using BET and BJH methods respectively. The electrochemical characterizations were carried out in three electrode system by cyclic voltammetry, chronoamperometry techniques. Glucose concentration range suitable for non-diabetic to diabetic is chosen for sensing i.e., 0.1 to 11.1 mM/L. The sensor has shown an excellent and selective response for glucose concentration. The electrochemical sensor is found with response sensitivity of 98% for glucose as compared to ascorbic acid (12%), folic acid (3%), urea (5%), potassium chloride (6%) and NaCl (13%) interferers. Further, repetitive response on same electrode presents its reproducibility and sensitivity for glucose indicating its potential application as glucose sensor.
There is strong recent interest in ultrathin, flexible, safe energy storage devices to meet the various design and power needs of modern gadgets. To build such fully flexible and robust ...electrochemical devices, multiple components with specific electrochemical and interfacial properties need to be integrated into single units. Here we show that these basic components, the electrode, separator, and electrolyte, can all be integrated into single contiguous nanocomposite units that can serve as building blocks for a variety of thin mechanically flexible energy storage devices. Nanoporous cellulose paper embedded with aligned carbon nanotube electrode and electrolyte constitutes the basic unit. The units are used to build various flexible supercapacitor, battery, hybrid, and dual-storage battery-in-supercapacitor devices. The thin freestanding nanocomposite paper devices offer complete mechanical flexibility during operation. The supercapacitors operate with electrolytes including aqueous solvents, room temperature ionic liquids, and bioelectrolytes and over record temperature ranges. These easy-to-assemble integrated nanocomposite energy-storage systems could provide unprecedented design ingenuity for a variety of devices operating over a wide range of temperature and environmental conditions.
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