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• MAF-rGO hybrid is verified for better arsenic (As) remediation under visible light (λ > 420 nm). • Photo-catalytic/electrocatalytic synergised MAF-rGO: High photocurrent density (0.9 mA cm−2). • XPS analysis confirmed the occurrence of redox reactions and ligand exchange phenomenon. • CV studies provide the mechanism of electro-sorption through reduction and sorption. • Sustainable use of sludge as ultra-high stable supercapacitor electrode (~100,000 cycles). Synergistic Mn-Al-Fe impregnated rGO hybrid (MAF-rGO) is developed and verified for arsenic remediation. Preliminary adsorption studies are observed through vibrational spectroscopy and morphological tools. Adsorption isotherms are fitted by Freundlich model multilayer sorption with a loading of 402 mg g−1 [As(III)], and 339 mg g−1 [As(V)]. Adsorption kinetics study in competing ion environment [SO 4 2−, PO 4 3−, NO 3 −, CO 3 2−] confirms the PSO model-controlled chemisorption as the rate-limiting step. The irradiation of white light (> 420 nm) in adsorption kinetics study shows a two-fold increase in the arsenic loading parameters (5–10 min). Multiplet peaks in As3d spectra (XPS) confirm the transformation of arsenic species in the near-surface region of hybrid [i.e., As(III), As(V)]. The occurrence of redox-active, ligand-exchange reactions are confirmed by individual Mn2p, Fe2p, Al2p, O1s, and C1s spectra. The dedicated electrochemical study confirms arsenic decontamination occurred through both reduction and sorption (i.e., electrosorption). An energy bandgap (E g) of 2.17 eV resulted in the photocatalytic activity, which enhanced the arsenic remediation. Photo-electrocatalytic synergism resulted in high photocurrent densities (0.2–0.9 mA cm−2) with charge separation [e−–h+], and built-in potential abilities (Schottky-junction; Water-splitting). Arsenic-treated hybrid (i.e., sludge) is observed with an ultra-high stable charge–discharge cyclic performance for 100,000 cycles (~77 %) with improved specific-capacity of 125 F g−1 over pristine hybrid (92 F g−1). The better electrochemical parameters of sludge are due to the efficient lithiation/de-lithiation process supported by adsorbed arsenic. This work proposes sustainable approach towards environmental remediation and energy storage applications. [ABSTRACT FROM AUTHOR]

In the present study, the green approach has been adopted for the reduction of graphene oxide (GO) using cow urine and urea, which were further spray-coated to fabricate graphene nanosheets (GNs) based transparent conducting films (TCFs). Raman analysis reveals the I D /I G intensity ratio of ~1.25, 1.39 for synthesized GNs by cow urine and urea, respectively. It indicates the removal of oxygen spices from GO, which is further confirmed by elemental analysis and FTIR. XRD, Raman and Urbach energy confirm the enhanced defects and lattice disorders, which are attributed to nitrogen incorporation, vacancies, and other structural defects. The presence of pyridinic-N defects as revealed by XPS and other structural defects has changed the electrical and optical properties of GNs. A detailed comparative study has been done to compare the electrical and optical properties of spray-coated TCFs over the quartz substrate. The enhanced conductivity in CGF (coated film using GN synthesized by cow urine) and UGF (coated film using GN synthesized by urea) might be due to presence of pyridinic-N and oxygen species removal, while enhanced transmissivity is due to presence of less number of graphene layers. UGF, which is thermally annealed at 900 °C shows the best performance with sheet resistance ~1.78 kΩ/□ and transmittance ~71.16%. Image 1 • GNs have been synthesized via green route avoiding hazardous chemicals. • Structural defects affect electrical conductivity and optical transparency. • Spray coating technique has been used for the one step fabrication of GNs based TCFs. • Best performance of TCF exhibits sheet resistance ~1.78 kΩ/□ and transmittance ~71.16%. [ABSTRACT FROM AUTHOR]

Heteroatom doped carbon structures are widely recognized as efficient catalysts for oxygen reduction reaction (ORR). Herein, chicken feather rachis (FR), a poultry industry biowaste is explored as a novel precursor for ORR catalysis. This study comprises the effect of pyrolysis temperature on the structural characteristics and electrocatalytic performance of prepared electrocatalysts. N-doped carbon (NC) synthesized at 950 °C is further activated using KOH, ZnCl 2 , and H 3 PO 4 at different temperatures. Poultry feather fiber (FF) derived samples were also prepared for comparison. KOH activated NCA-900 (NCA-K-900) exhibits the superior electrochemical performance in terms of onset potential (−0.02 V vs Ag/AgCl) in comparison to similar catalysts previously reported and prepared from feather fiber, which exhibits ~ −0.2 V vs Ag/AgCl. This is attributed to the mesoporous structure and increased ORR active C N sites in FR derived samples as confirmed by adsorption isotherm and XPS analysis, respectively. In addition, it shows 96% current stability in chronoamperometric measurements for 15 h. It is better than the previously reported electrocatalyst prepared from coconut shell (90%, 13 h) and egg yolk (91%, 9 h) respectively. Hence, this study presents an improved environment friendly substitute for ORR catalysis. Unlabelled Image • Activated nitrogen doped carbon (NCA) is prepared from chicken feather rachis (FR). • FR is the central stem of feathers and is more crystalline compared to ramus (FF) • NCA is explored for improved catalysis over FF derived electrocatalysts for ORR • NCA-K-900 exhibits an onset potential (-0.02 V) and 96% current stability for 15 h • lectrochemical results are further supported by structural and chemical studie [ABSTRACT FROM AUTHOR]

Background: Harmful microorganisms like pathogens significantly impact human health. Meanwhile, industrial growth causes pollution and water contamination by releasing untreated hazardous waste. Effective treatment of these microorganisms and contaminants is essential, and nanocomposites may be a promising solution. The present attempt demonstrates the green synthesis of α-Fe2O3@TiO2 nanocomposites (FTNCs) for the effective treatment of pathogens and organic contaminants., Methods: The α-Fe2O3@TiO2 nanocomposites (FTNCs) has been synthesized through a green approach utilizing curcumin extract. Curcumin (Turmeric) extract (TEx) was prepared by washing, drying, and crushing 5 g of turmeric, then boiling it in 100 mL distilled water at 70°C for 1 hour. Metal salts (Fe3+/Ti4+, 2:1) were added to 100 mL of TEx under continuous stirring at 70°C for 24 h. The solution was rinsed and dried at 80°C overnight and heated at 300°C for 3 h to remove impurities., Results: Synthesized FTNCs have been tested for the potent antibacterial activity against both Gram-positive (Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis) and Gram-negative bacteria (Escherichia coli, Salmonella Abony, Pseudomonas sp.). Observations discovered noteworthy inhibition of both Gram-positive and Gramnegative bacteria by FTNCs. Furthermore, the FTNCs system shows the energy band gap of ~2.6 eV which may suppress electron recombination, thereby enhancing photocatalysis and examined against Evans blue (EB) and Congo red (CR) dyes under UV and visible light (125 W) irradiation. The remarkable photocatalytic degradation efficiency (DE) for CR reached ~67.4% in 60 min., Conclusion: A simple green approach has been demonstrated for the synthesis of the FTNCs using curcumin-mediated reduction. As prepared FTNCs have been evaluated for potent antibacterial activity against both Gram-positive (Staphylococcus aureus, Bacillus subtilis, Enterococcus faecalis) and Gram-negative bacteria (Escherichia coli, Salmonella Abony, Pseudomonas sp.)., Observations: The results show that the highest ZID values have been obtained for 5 mg/mL concertation of FTNCs of ~14, 22,18, 21, and 20 and 29 mm for E. coli, S. abony, S. aureus, B. subtilis, E. faecalis, and Pseudomonas sp., respectively. Additionally, FTNCs demonstrate remarkable photocatalytic degradation efficiency against EB and CR dyes under UV (125 W) irradiation, achieving 56, 67% degradation within 60 minutes for EB and CR. The findings suggest that the FTNCs hold promise for long-term antimicrobial efficacy against various bacteria and offer the potential for addressing water and wastewater contaminants through photocatalysis., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Supercapacitors store energy due to the formation of an electric double layer (EDL) at the interface of the electrodes and electrolyte. The present article deals with the finite element study of equilibrium electric double layer capacitance (EDLC) in the mixed morphology electrodes comprising all three fundamental crystal structures, simple cubic (SC), body-centered cubic (BCC), and face-centered cubic morphologies (FCC). Mesoporous-activated carbon forms the electrode in the supercapacitor with (C 2 H 5 ) 4 NBF 4 /propylene carbonate organic electrolyte. Electrochemical interference is clearly demonstrated in the supercapacitors with the formation of the potential bands, as in the case of interference theory due to the increasing packing factor. The effects of electrode thickness varying from a wide range of 50 nm to 0.04 mm on specific EDLC have been discussed in detail. The interfacial geometry of the unit cell in contact with the electrolyte is the most important parameter determining the properties of the EDL. The critical thickness of the electrodes is 1.71 μm in all the morphologies. Polarization increases the interfacial potential and leads to EDL formation. The Stern layer specific capacitance is 167.6 μF cm -2 in all the morphologies. The maximum capacitance is in the decreasing order of interfacial geometry, as FCC > BCC > SC, dependent on the packing factor. The minimum transmittance in all the morphologies is 98.35%, with the constant figure of merit at higher electrode thickness having applications in the chip interconnects. The transient analysis shows that the interfacial current decreases with increasing polarization in the EDL. The capacitance also decreases with the increase of the scan rate.

The continuum theory has been used to analyze the polarization, ion crowding, and electrostatic forces of the electric double layer in the electrode materials having simple cubic (SC), body-centered cubic (BCC), and face-centered cubic (FCC) morphologies. The study manifests the effect of thickness of electrodes, electrode's particle size, and porosity on electric double-layer specific capacitance (EDLC). Electrochemical interference and the specific capacitance depend on the packing factor. The larger particle size decreases the specific capacitance, but porosity increases due to more surface area. Due to symmetry, SC, BCC, and FCC morphologies have 1, 3, and 5 spheres in a unit cell. The number of unit cells is varied from 1 to 100 in model 1 to analyze the effect of electrode thickness. Model 2 has three unit cells to understand the effect of porosity, and only pore lengths are varied. The critical thickness of the electrodes is the integer multiples of 1.71 μ m in all the morphologies. The Stern layer-specific capacitance is 167.6 μ F cm -2 in all cases. The EDLC in BCC is around 5.6-7.6 μ F cm -2 in the steady state that is intermediate between SC and FCC morphologies. The more dense packing of carbon particles in a unit cell increases the energy storage capabilities of electrodes. The average electrode permittivity slightly decreases due to the combined effect of the high electric field, status of polarization, and electrode particle size. The least optical transmission of electrodes is 98.35%., (© 2023 IOP Publishing Ltd.)

Copper-based ternary metal oxide (i.e., Cu0.52Al0.01Fe0.47O4) impregnated reduced graphene oxide nanohybrid is verified for microbial and arsenic treatment. Growth inhibition of colonies are observed around 99.99% (E. coli), and 99.83% (S. aureus) at 10-20 μg/mL of hybrid dosage, respectively. The inhibition rates for both the colonies are increased to 99.9998% at 80 μg/mL. TEM images have shown insight of cell-content/lipid leakage behavior after inoculating with the hybrid. The efficient hindrance towards microbial colony growth is attributed to better charge transfer, reactive oxygen species generation, and metal-ion release. Maximum arsenic sorption capacities are observed around 248 and 314 mg/g for As(III), and As(V), respectively (C i  ~ 500 ppm). Surface morphology studies onto arsenic adsorption are reported with atomic force microscope, and FT-IR/Raman analysis. A detailed discussion onto individual spectra of As 3d spectra confirmed the occurrence of redox transformation in arsenic species [As(III)]. The variation in the quantity (at. %) of oxygen functional groups in O1s spectra (i.e., M-O, M-OH, and -OH 2 ) onto the hybrid supported the ligand-exchange behavior. Cyclic voltammetry study in arsenic electrolytes (10 µM - 1 mM) provides the occurrence of various in-situ electrochemical reactions supporting the redox activity. A significant electromagnetic wave absorption characteristics of the present hybrid is proposed with plausible airborne antimicrobial-agent abilities., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Supercapacitors are electrochemical energy storage devices having high capacitance, high power density, long cycle life, low cost, easy maintenance, and negligible environmental pollution. The formation of an electric double layer at the electrode-electrolyte interface is mostly responsible for supercapacitors' energy storage. The simulation study of equilibrium electric double-layer capacitance (EDLC) in 3D arranged mesoporous carbon electrodes with a simple cubic morphology and interdigitated electrodes has been done. Continuum theory has been utilized to study the underlying processes involved in EDLC. Interfacial polarization and ion crowding depend on the electrode's critical thickness. Porosity increases the capacitance due to the increase in the electrode surface area. The diffuse-layer specific capacitance of ordered mesoporous carbon electrodes in a (C 2 H 5 ) 4 NBF 4 /propylene carbonate organic electrolyte is in the range of 3.2-13.3 μF cm -2 , varying according to the electrode thickness. The Stern-layer specific capacitance is 167.6 μF cm -2 , and total equilibrium EDLC is in the range of 3.1-12.3 μF cm -2 . The effect of the electric field at the electrode-electrolyte interface on reducing electrolyte permittivity has also been discussed. The EDLC of carbonized interdigitated electrodes is analyzed in a 6 M KOH electrolyte. The diffuse-layer specific capacitance ranges from 118.7 to 352.0 μF cm -2 depending on the width of the interdigitated electrodes. The Stern-layer specific capacitance is 91.2 μF cm -2 , and the total EDLC value is 51.6-72.4 μF cm -2 . The modeling and simulation approach can be applied to different mesoporous electrodes by varying the supercapacitor component's parameters and geometry.

This Spotlight on Applications highlights the significant impact of microwave-assisted methods for synthesis and modification of carbon materials with enhanced properties for electrodes in energy storage applications (supercapacitors and batteries). For the past few years, microwave irradiation has been increasingly used for the synthesis of carbon materials with different morphologies using various precursors. Microwave processing exhibits numerous advantages, such as short processing times, high yield, expanded reaction conditions, high reproducibility, and high purity of products. On this frontier research area, we have discussed microwave-assisted synthesis, defect creation, simultaneous reduction and exfoliation, and heteroatom doping in carbon materials. By careful manipulation of microwave irradiation parameters, the method becomes a powerful and efficient tool to generate different morphologies in carbon-based materials. Other important outcomes are the flexible control over the degree of reduction and exfoliation of graphene derivatives, the generation of defects in graphene-based materials by metals, the intercalation of metal oxides into graphene derivatives, and heteroatom doping of graphene materials. The Spotlight on Applications aims to provide a condensed overview of the current progress in carbon-based electrodes synthesized by microwave, pointing out outstanding challenges and offering a few suggestions to trigger more research endeavors in this important field.

Rational and strategic fabrication of cost-effective, active and durable oxygen reduction reaction (ORR) electrocatalyst is the bottle-neck for the commercialization of fuel cells and metal-air batteries. Atomically dispersed nickel (Ni)/nickel sulfide (Ni x S y ) anchored on heteroatom doped networked hierarchical porous carbonaceous sheets are synthesized from nickel nitrate and guanidine thiocyanate. The sample annealed at 750 °C followed by acid-treatment (Ni-GT-750-A) emerges as the best performing pH-universal ORR catalyst with an onset potential of 0.91 (0.1 M KOH) and 0.89 V (0.1 M HClO 4 ) vs. reversible hydrogen electrode (RHE). It also exhibits better current durability (95.0 and 60%) and methanol tolerance (90.6 and 80.3%) in comparison to the commercial catalyst (65.0, 27, -33.0 and 16.5%) in alkaline and acidic media, respectively. An insight into the microstructure and ORR-active chemical sites is obtained with the aid of electron microscopic (FE-SEM and HR-TEM) and physiochemical (sorption isotherm, XRD, Raman and XPS) studies, respectively. The enhanced activity results from the synergistic influence of metallic ORR-active sites in hierarchical porous doped defective carbon support, which provides the well-interlinked conducting channel for electron transfer and additional ORR-active sites. The introduced electrocatalyst establishes Ni decorated doped carbon systems as potential revolutionary substitutes for commercial systems., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Microsized and shape-versatile flexible and wearable lithium-ion batteries (LIBs) are promising and smart energy storage devices for next-generation electronics. In the present work, we design and fabricate the first prototype of microsized fibrous LIBs (thickness ≈ 22 μm) based on multilayered coaxial structure of solid-state battery components over flexible and electrically conductive carbon fibers (CFs). The micro coaxial batteries over the CF surface were fabricated via electrophoretic deposition and dip-coating methods. The microfiber battery showed a stable potential window of 2.5 V with an areal discharge capacity of ∼4.2 μA h cm -2 at 13 μA cm -2 of the current density. The as-assembled battery fiber delivered a comparable energy density (∼0.006 W h cm -3 ) with solid-state lithium thin-film batteries at higher power densities (∼0.0312 W cm -3 ). The fibrous batteries were also connected in parallel and in series to deliver large current and high voltage, respectively. The fibrous battery also retains up to 85% discharge capacity even after 100 charge-discharge cycles. Furthermore, these battery fibers performed well under both static and bending conditions, which shows the robustness of the battery fiber. Therefore, this type of fibrous microbattery can be used in advanced flexible and wearable microelectronics, bioelectronics, robotics, and textile applications.

Strong EM wave absorption and lightweight are the foremost important factors that drive the real-world applications of the modern microwave absorbers. This work mainly deals with the design of highly efficient microwave absorbers, where a hierarchical carbon nanotube (CNT) forest is first grown on the carbon fiber (CF) through the catalytic chemical vapor deposition method. The hierarchical carbon nanotube grown on the carbon fiber (CNTCF) is then embedded in the epoxy matrix to synthesize lightweight nanocomposites for their use as efficient microwave absorbers. The morphological study shows that carbon nanotubes (CNTs) self-assemble to form a trapping center on the carbon fiber. The electromagnetic characteristics of resultant nanocomposites are investigated exclusively in the X-band (8.2-12.4 GHz) using the network analyzer. The synthesized nanocomposites, containing 0.35 and 0.50 wt % CNTCFs, exhibit excellent microwave absorption properties, which could be attributed to the better impedance matching conditions and high dielectric losses. The reflection loss (RL) of -42.0 dB (99.99% absorption) with -10 dB (90% absorption) and -20 dB (99% absorption) bandwidths of 2.7 and 1.16 GHz, respectively, is achieved for 0.35 wt % CNTCF loading at 2.5 mm thickness. The composite with 0.50 wt % CNTCF loading illustrates substantial absorption efficiency with the RL reaching -24.5 dB (99.65% absorption) at 9.8 GHz and -10 dB bandwidth comprising 84.5% of the entire X band. The excellent microwave properties obtained here are primarily due to the electric dipole polarization, interfacial polarization, and unique trapping center. These trapping centers basically induce multiple reflections and scatterings, which attenuate more microwave energy. This investigation opens a new approach for the development of extremely lightweight, small-thickness, and highly efficient microwave absorbers for X-band applications.

Development of printable and flexible energy storage devices is one of the most promising technologies for wearable electronics in textile industry. The present work involves the design of a printable and flexible all-solid-state rechargeable battery for wearable electronics in textile applications. Copper-coated carbon fiber is used to make a poly(ethylene oxide) (PEO)-based polymer nanocomposite for a flexible and conductive current collector layer. Lithium iron phosphate (LiFePO 4 ) and titanium dioxide (TiO 2 ) are utilized to prepare the cathode and anode layers, respectively, with PEO and carbon black composites. The PEO- and Li salt-based solid composite separator layer is utilized for the solid-state and safe electrolyte. Fabrication of all these layers and assembly of them through coating on fabrics are performed in the open atmosphere without using any complex processing, as PEO prevents the degradation of the materials in the open atmosphere. The performance of the battery is evaluated through charge-discharge and open-circuit voltage analyses. The battery shows an open-circuit voltage of ∼2.67 V and discharge time ∼2000 s. It shows similar performance at different repeated bending angles (0° to 180°) and continuous bending along with long cycle life. The application of the battery is also investigated for printable and wearable textile applications. Therefore, this printable, flexible, easily processable, and nontoxic battery with this performance has great potential to be used in portable and wearable textile electronics.

Arsenic [As(III) and As(V)] adsorption on aluminum substituted cobalt ferrite (Co-Al-Fe) ternary metal oxide adsorbent is reported by means of qualitative and quantitative spectroscopy tools. IR and Raman active signals were observed around 810-920 cm -1 band indicate different As-OH complexed and As-O uncomplexed stretching vibrations on to the adsorbent. The adsorption behavior of arsenic (III and V) onto these adsorbents is studied as a function of contact time, different concentrations, and pH conditions. The kinetics study on adsorption were performed to understand nature of adsorption which supports the Pseudo Second Order (PSO) model. The adsorption isotherms study indicates Freundlich type of adsorption. The maximum adsorption capacity of Co-Al-Fe adsorbent is observed around 130 and 76 mg g -1 for As(III) and As(V) systems, respectively. Detailed XPS study of As 3d, Fe 2p, Co 2p, and O 1s spectra has been reported in explaining the redox behavior and ligand exchange reactions in supporting arsenic adsorption mechanism.

Hierarchical 3D nanocomposite electrodes with tube brush-like morphology are synthesized by electrochemically depositing polypyrrole (PPY) on carbon nanopetal (CNP) coated carbon fibers (CFs). Initially CNPs are synthesized on CF substrate by chemical vapour deposition. The CNPs synthesized on CF (CNPCF) are further used as an electrically conducting large surface area bearing template for the electropolymerization of PPY in order to fabricate CNPCF-PPY nanocomposite electrodes for supercapacitors (SCs). The CF in CNPCF-PPY nanocomposite functions as (i) a mechanical support for the CNPs, (ii) a current collector for the SC cell and also (iii) to prevent the agglomeration of CNPs within the CNPCF-PPY nanocomposite. Transmission electron microscopy and scanning electron microscopy are used to examine the surface morphology of CNPCF-PPY nanocomposites. The chemical structure of the nanocomposites is analysed by Fourier transform infrared spectroscopy. X-Ray photoelectron spectroscopy has been used to understand the chemical bonding states of the hierarchical CNPCF-PPY nanocomposites. The electrochemical properties of symmetric type CNPCF-PPY SC cells are examined by electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic charge-discharge measurements. The hierarchical CNPCF-PPY SC exhibits a maximum gravimetric capacitance of 280.4 F g(-1) and an area specific capacitance of 210.3 mF cm(-2) at a current density of 0.42 mA cm(-2). The CNPCF-PPY SC cell exhibits good cycling stability of more than 5000 cycles. The present study proclaims the development of a novel lightweight SC with high-performance.

Elastic chitosan-gelatin cryogels of varying concentration of polymer precursors have been synthesized using glutaraldehyde as a crosslinking agent. The optimum co-polymer ratio of chitosan to gelatin was found to be 1:4 at the temperature of -12 degrees C for synthesis of chitosan-gelatin hybrid cryogels. chitosan-gelatin cryogels synthesized with low viscosity chitosan were morphologically better than those formed with medium and high viscosity chitosan. Pore diameters of chitosan-gelatin cryogels as measured by scanning electron microscopy (SEM) was in the range of 30-100microm. While mercury porosimetry analysis revealed the majority of pores of the scaffold lying in the range of 30-50microm. Porosity of chitosan-gelatin cryogels was found to be greater than 90% using Archimedes's principle. Unconfined compression tests showed significant elasticity of chitosan-gelatin cryogels and maintained their physical integrity even after compressing them up to 80% of their original length. The elastic modulus varied in the range of 36-39kPa. Cyclic deformation analysis performed by compression of chitosan-gelatin cryogels with varying strains (10, 20 and 40%) showed no cracking or any significant deformation. The degradation of chitosan-gelatin cryogels was found up to 13.58+/-1.52% at 37 degrees C within 8 weeks of incubation under sterile conditions and the cryogels swelled up to 90% of their capacity within two min. Efficient cell adherence, proliferation and extracellular matrix (ECM) secretion was observed by growing fibroblast (Cos-7) cell line on chitosan-gelatin hybrid cryogels which indicate potential of the material for tissue engineering applications.