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AC electrical measurements were carried out on iodine doped, CaCu 3 Ti 4 O 12-x I x (x = 0, 0.005, 0.05 and 0.2) ceramic specimens sintered at 1100 °C for 12 h in the temperature (300–450 K) and frequency (20 Hz - 1 MHz). The crystalline structure, microstructure, and oxidation state of various ions of pure and iodine-substituted sintered specimens were carried out through XRD, SEM, and XPS, respectively. The dielectric relaxations in grains, grain boundaries, and sample-electrode interfaces for different compositions were investigated through impedance and modulus spectroscopic techniques and were reported in the first part of the investigation. It revealed the involvement of similar types of charge carriers in conduction and relaxation processes in grains and grain boundaries, respectively. This second section emphasizes the dielectric and conduction properties of CaCu 3 Ti 4 O 12 (CCTO) with iodine doping at the anion site. The XPS study reveals that the concentration [ V O • • ] is reduced, and [ V M ″ ] gets increased with increasing concentration of iodine from x = 0.05 to 0.2. This observation also supports the point defect model as reported earlier for charge compensation of impurity defect I O • i.e., with increasing substitutions of iodine, the charge on I O • change from electronic to cationic vacancies, V T i / / / / or copper V C u / / or both to keep electrical charge neutrality. The metal ions get segregated at grain boundaries. This, in turn, will minimize hopping due to electrons between Ti4+ and Ti3+ or Cu2+ and Cu1+. As a result, it increases resistivity and minimizes dielectric losses for the higher concentration of iodine doping. Thus, a high concentration of iodine doping at the oxygen site promotes the formation of a barrier layer capacitor. [ABSTRACT FROM AUTHOR]

A unique approach of Co-doping at the Mn site was used to prepare spherical shaped LiMn 0.5 Co 0.5 PO 4 @C (LMCP@C) nanoparticles by supercritical fluid hydrothermal method. The high-resolution transmission electron microscopy (HR-TEM) study of LMCP@C nano-particles explores that the average diameter of nanospheres is in the range of 7–50 nm. XPS analysis reveals that the Mn/Co-ion exists in the divalent oxidation state. First-principle calculations explore that Co doping increases the operating voltage, specific capacity, gravimetrical energy, and power density. The corresponding theoretical values are 5.23 V, 169.1 mA h g−1, 85.164 kW h kg−1, and 85.164 kW kg−1. At the same time, the theoretical volumetric energy and power densities are 8.008 kWh cm−3 and 8.008 kW cm−3. It also reveals that Co-doping enhances the bulk modulus (∼87 GPa), shear modulus (∼92.5 GPa), and Poisson ratio (0.107). The electrochemical analysis of secondary Li-ion batteries (LIBs) explores that the initial discharge capacities at 0.1 and 100 C are 156.5, and 80 mA h g−1, gravimetrical energy, and power densities are within the range of 591.3–312 W h kg−1 and 312.2 kW kg−1, respectively. All-solid-state thin and flexible LIBs have the initial discharge capacities under different bending states at 0.1 C within the range of 141 - 140 mA h g−1. Volumetric power and energy densities are within the limit of 6.575–6.30 W cm−3 and 0.6575–0.631 W h cm−3, respectively. [Display omitted] • LMCP@C nanocomposites exhibit enhanced cyclic stability and low capacity fading. • LMCP@C nanocomposites show high power density of 312.191 kW kg−1 at 100 °C. • Co-doping improves the structural stability and electrochemical performance. • The areal capacities of conventional battery are within 5.6–3.06 mA h cm−2. • Bulk and Young modulus of LMCP from DFT calculations are ∼87 and 92.5 GPa. [ABSTRACT FROM AUTHOR]

Effect of degree of sulfonation on dynamic mechanical properties, dehydration rate, crystallinity, thermal stability and other fuel cell properties ( e.g. proton conductivity, ion exchange capacity, water uptake capacity, etc. ) of SPEEK membrane are studied and correlated with microstructure. With increasing degree of sulfonation (DS), α-relaxation peak shifts from 135 to 166 °C, while β-relaxation changes from 76 to 37 °C. This peak attribution indicates a plasticizing effect of SO 3 H group within the crystalline region. Thermal stability of SPEEK decreases while peak degradation temperature for desulfonation and glass transition temperature increase from 320-340 and 191–210 °C, respectively with increasing DS from ∼72 to ∼128%. Likewise, small angle X-ray scattering peak at scattering vector of 0.2 Å −1 shifts to 0.28 Å −1 with an associated increase in intensity due to the evolution of microstructure. Increase in number of scattering centers with progressive sulfonation leads to ionic aggregation, which is the main responsible factor for such evolution. Ionic aggregation is further confirmed by the occurrence of two closely spaced melting peaks in the range of 322–328 and 361–365 °C in differential scanning calorimetry analysis. Dehydration rate gradually increases with increasing DS. Ion exchange capacity, proton conductivity, water uptake and dehydration rate increase from ∼0.49 to ∼2.43 mmol g −1 , ∼1.07 × 10 −4 to ∼2.9 × 10 −2 Scm −1 , ∼20.36 to ∼135.3% and ∼0.296 to ∼0.51 sec −1 , respectively with increase in DS from ∼72 to ∼128%. Microstructure become more homogeneous (less phase separated) at DS of ∼128% resulting in continuous ionic channels for proton conduction. [ABSTRACT FROM AUTHOR]

• Chemical-free synthesis technique was employed for the synthesis of the composite. • Waste keratin fibers were used as a carbon precursor. • ROKF-2 delivers excellent true specific capacitance of 2556 F g−1 at 2 A g−1. • In double hybridization assembly, the device depicts a true capacitance of 238 F g−1 at 1 A g−1. • In K 3 Fe(CN) 6 redox mediator electrolyte, the device shows an energy density of 265 Wh Kg−1 at a power density of 1000 W kg−1. • The flexible device delivers 142 mF cm−1 at a scan rate of 10 mV s−1. The present study exploits a chemical-free, low-cost, simple, scalable, and facile synthesis technique using an in-situ methodology to prepare composite electrodes. The as-synthesized composite is utilized as a hybrid electrode for supercapacitor application. The hydrous RuO 2 and keratin fiber-derived carbon (ROKF-2) show excellent specific capacitance of 3542 F g−1 at 2 A g−1. However, true analysis reveals that the actual capacitance is 2556 F g−1. It focuses on delivering the actual performance of the hybrid device by eliminating the use of conventional equations. In symmetric assembly, the excellent device capacitance of 121 F g−1 at 1 A g-1 is achieved while maintaining its coulombic efficiency above 90% throughout the applied current. The double hybridization assembly shows the broadening of working potential with an outstanding energy density of 226 Wh kg−1 at 1000 W Kg−1. Upon introducing redox additives, the performance increases, suggesting their effective contribution to the charge storage process. In the presence of K 3 Fe(CN) 6 , the device delivers a remarkable rate capability of 50% till 5 A g−1, whereas, in the KI environment, the device efficiency gets enhanced ∼45%. The wire-shaped flexible device shows a specific capacitance of 142 mF cm−1 at a scan rate of 10 mV s−1 with an energy density of 0.03 mWh cm−1 at 33 W cm−1. The process approaches a chemical-free process for the composite synthesis, which can be utilized in various hybridization modes. The study eliminates the traditional equations to minimize the overestimated electrochemical performance. The prepared composites pave a new path in hybrid energy storage systems. [Display omitted] [ABSTRACT FROM AUTHOR]

Thermoelectric materials are crucial in renewable energy conversion technologies to solve the global energy crisis. They have been proven to be suitable for high-end technological applications such as missiles and spacecraft. The thermoelectric performance of devices depends primarily on the type of materials used and their properties such as their Seebeck coefficient, electrical conductivity, thermal conductivity, and thermal stability. Classic inorganic materials have become important due to their enhanced thermoelectric responses compared with organic materials. In this review, we focus on the physical and chemical properties of various thermoelectric materials. Newly emerging materials such as carbon nanomaterials, electronically conducting polymers, and their nanocomposites are also briefly discussed. Strategies for improving the thermoelectric performance of materials are proposed, along with an insight into semiconductor physics. Approaches such as nanostructuring, nanocomposites, and doping are found to enhance thermoelectric responses by simultaneously tuning various properties within a material. A recent trend in thermoelectric research shows that high-performance thermoelectric materials such as inorganic materials and carbon nanomaterials/electronically conducting polymer nanocomposites may be suitable for power generation and energy sustainability in the near future. [ABSTRACT FROM AUTHOR]

This study reports the sulfonated poly ether ether ketone/polypyrrole/aluminum phosphate nanocomposite as membrane for polymer electrolyte membrane fuel cell. Aluminum phosphate nanoparticles of average crystallite size ∼62 nm were synthesized by sol–gel method followed by calcination at 900 °C. The nanocomposite membranes were fabricated by immersing the sulfonated poly ether ether ketone film (with and without embedded aluminum phosphate nanoparticles) in pyrrole/methanol mixture followed by in-situ polymerization of absorbed pyrrole within the pores of support material. The membrane containing ∼4 wt% polypyrrole and 5 wt% aluminum phosphate showed ionic conductivity as high as 3.14 × 10 −4 S cm −1 . Approximately 68.8% reduction in water desorption rate was achieved in nanocomposite membrane compared to virgin sulfonated poly ether ether ketone. Membranes were thermally stable up to 300 °C and also exhibited low water and methanol uptake capacity that are favorable for direct methanol fuel cell application. Microstructure was examined by scanning electron microscope and correlated with the observed functional properties. [ABSTRACT FROM AUTHOR]

Heteroatom doped microfibrous carbon having 3D networked structure has been synthesized by pyrolysis of poultry featherfiber (PFF) at different temperatures ranging between 400 and 1000 °C. Structural parameters, namely surface roughness of the PFF derived carbon (CN x ) microfibers, concentrations and chemical states of the dopants, etc. have been found to vary significantly with pyrolysis temperature (T p ). Further, correlations between oxygen reduction reaction (ORR) activity and the structural parameters have been investigated. High ORR activities of the CN x synthesized at T p ≥ 800 °C are correlated with their high surface roughness and high fractions of ORR active functionalities. The CN x samples synthesized at T p ≥ 800 °C exhibit ORR activity higher than that of Pt. This, combined with the networked structure, high electrochemical as well as thermal stabilities and cost-efficient synthesis of the CN x make it interesting ORR electrocatalyst for low-working temperature fuel cells. [ABSTRACT FROM AUTHOR]

Poultry featherfiber (PFF), the soft fibrous part of poultry feathers, is used as the novel precursor to derive N-, O- and S-doped-carbon (CN x ) electrocatalysts. The catalysts are synthesized by a low-temperature pyrolysis of PFF or a mixture of PFF and Fe/Co salts in varying concentrations, followed by acid-treatment to remove the metal from pyrolyzed samples. Electrochemical measurements in alkaline media exhibit significant ORR electrocatalytic activity of CN x with an ORR onset potential of ∼-230 mV (vs. Ag/AgCl), which is comparable to Pt (∼-210 mV) under similar conditions. Despite the absence of metal-carbon bonds, the CN x electrocatalysts synthesized in presence of Fe/Co exhibit catalytic activity significantly higher than that of the CN x synthesized without metals. This is attributed to the modified chemical states of C-N and C-O sites due to the presence of Fe/Co during pyrolysis. Hence, presence of metal precursors during pyrolysis affects the ORR activity of CNx indirectly. The CN x catalysts synthesized in presence of varying Fe to Co ratio contain varying N-content and the ORR peak current is found to vary linearly with the N-content. Observed ORR activity of the present catalyst makes it a suitable Pt-free catalyst for low temperature fuel cells. [ABSTRACT FROM AUTHOR]

In the present study, we demonstrate the simultaneous efficient removal of heavy metals such as Pb(II), Cd(II) and Cr(III) ions as well as methylene blue (MB) dye from water by titania/activated carbon/carbonized epoxy (TiO 2 /AC/CE) nanocomposite with high activity and easy separation. A simple one-step solvothermal process is used for the synthesis of TiO 2 nanosphere for TiO 2 /AC/CE nanocomposite. The as-synthesized TiO 2 /AC/CE nanocomposite is characterized using XRD, SEM, TGA, BET, Raman, FTIR, and UV–vis spectroscopy. The adsorption/degradation characteristics of TiO 2 /AC/CE nanocomposite are evaluated with varying contact time and at a fixed solution pH. The addition of AC on TiO 2 significantly improves the activity of TiO 2 . The TiO 2 /AC/CE nanocomposite is found to be much active than bare TiO 2 nanoparticles and exhibits easy separation. Here, AC significantly enhances the surface area of the TiO 2 /AC/CE nanocomposite and suppresses the phase transition of TiO 2 from photoactive anatase to less active rutile. The performance of the TiO 2 /AC/CE nanocomposite for the decomposition of MB is found to be governed by the crystallinity of anatase phase of TiO 2 . For the removal of Pb(II) ions, the as-synthesized TiO 2 /AC/CE nanocomposite shows a high activity, where 97% of the Pb(II) ions are removed from aqueous solution. [ABSTRACT FROM AUTHOR]

An order of magnitude rise in the thermoelectric (TE) performance of the PbSe, a scalable and easy-to-manufacture TE material, has been achieved by incorporating reduced graphene oxide (Gr) nanoplatelets in a PbSe/PbSeO 3 heterostructure formed by acoustic cavitation-assisted oxidation. The fabricated Gr/PbSe/PbSeO 3 nanocomposites exhibit high TE performance with an exceptionally high Seebeck coefficient coupled with low thermal conductivity. The variation in the Seebeck coefficient has been attributed to a reduction in charge carrier mobility due to the ferroelectric polarization effect. Furthermore, the increase in electrical resistivity is minimized by adding graphene. At an optimal weight fraction (0.2 wt%), graphene nano-inclusions lead to superior Seebeck coefficient values as high as ~2000 μV/K at ~500 K, providing high overall TE performance. This study shows substantial changes in the TE properties of PbSe through the incorporation of graphene and PbSeO 3. The understanding and methodology developed in this study can be exploited for the scalable manufacturing of high-performance TE materials. [Display omitted] • PbSe/nano-PbSeO 3 /Graphene attains abnormal scattering process with temperature. • Gr:PbSe/PbSeO 3 exhibits high Seebeck coefficient of ~ 2400 µV/K at 475 K. • Gr:PbSe/PbSeO 3 exhibits lower thermal conductivity of ~ 0.2 W/mK between 450 and 600 K. • High Seebeck coefficient is due to reduced mobility and high electrical resistance. [ABSTRACT FROM AUTHOR]

Abstract: The nickel–phosphorous (Ni–P) coating on carbon fiber was studied, using sodium hypophosphite as a reducing agent in alkaline medium. The effects of process parameters such as time, stabilizer concentrations, pH of the plating bath and plating bath''s temperature on the electroless Ni–P coating efficiency were investigated. Structural study using X-ray diffraction (XRD) indicates that nickel deposition rate increases with increasing coating time and temperature. The nickel (Ni) recovery efficiency decreases with an increase of stabilizer concentration. From scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX), it has been confirmed that the coating thickness and nickel content increase with an increase of coating time and temperature. The bath temperature of 25°C, pH of 9, and stabilizer concentration of 25g/L is good to get a good and uniform coating of Ni on carbon fiber. Thermal stability was studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). From TGA study it is evident that the nickel coating increases thermal stability of the nickel-coated carbon fiber. I–V (current vs voltage) measurement shows Ni-coated fiber is more conducting in nature. [Copyright &y& Elsevier]

Abstract: The precision manufacturing technology always demands a good surface finish at low cost. This scenario drives both industries and research community to develop novel finishing processes. Presently, there are many techniques and one among them is abrasive flow machining (AFM) process. The media developed by optimum process variables mainly governs the performance of AFM. In the present experimental endeavor, an attempt is made in the direction of developing new media based on viscoelastic carrier and its characterization for fine finishing through AFM process. The newly developed media was again characterized through rheological properties. It is found that temperature, shear rate, creeping time and frequency have impact on rheological properties and the percentage ingredients of media govern trends of their relations. [Copyright &y& Elsevier]

Abstract: 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°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 30–100μm. While mercury porosimetry analysis revealed the majority of pores of the scaffold lying in the range of 30–50μm. 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°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. [Copyright &y& Elsevier]

Abstract: The thermal stability and degradation behavior of polypropylene (PP) particles having diameter varying from few micrometers to nanometers were studied by thermogravimetric analysis (TGA). The PP particles of average diameter ∼20μm, ∼10μm, ∼5μm, ∼1μm and <500nm were studied over a range of temperature from 25 to 600°C in N2 atmosphere and heating rates of 5, 10 and 15°C/min. Thermal stability of PP particles initially decreases and then increases as particle size further decreases to nanometer scale. The five single heating rate techniques such as Friedman, Freeman–Carroll, Chang, Coats–Redfern and second Kissinger; and three multiple heating rate techniques such as the first Kissinger, Kim–Park and Flynn–Wall were used to compute the kinetic parameters of degradation reaction, e.g., activation energy (E a), order of reaction (n) and frequency factor [ln(Z)]. The lifetime of macro-, micro- and nanosized PP particles was also estimated by a method proposed by Toop. It was found that the activation energy and lifetime of nanosized PP particles are moderately high compared to the microsized PP particles. Moreover, the decomposition temperature, order of reaction (n), frequency factor [ln(Z)] not only depend on the heating rate and calculation technique but also on the particle size of polymer. The results are compared with macrosized PP. [Copyright &y& Elsevier]

Microwave sintering drastically reduces the lattice distortion, strain that developed by ball milling and enhances Li-ion mobility highly beneficial for Li-ion batteries. In the present study, we have explored the preparation of nanocrystalline Li 2 TiO 3 with monoclinic structure using high energy ball milling followed by calcination at 700 °C for 2 h. Samples are microwave sintered at different temperatures and their X-ray diffraction pattern reveals the transformation of β → γ phase. The scanning electron microscopy studies confirm the well crystalline nature and average particles size in range of 20–40 nm. High-resolution transmission electron microscopy, Raman and Fourier transform infrared spectroscopic studies reveal that Li-ion migration occurs from tetrahedral site to octahedral site along c-direction, parallel to a-b plane. The specific heat, thermal diffusivity, conductivity measurements are performed in the temperature range of 30–800 °C. There is a significant improvement of alternating current conductivities (in the order of 10−3 S/cm) and low activation energies in the range of 0.1–0.38 eV. Electrochemical characteristics of microwave sintered Li 2 TiO 3 incorporated Li 2 TiO 3.LiNi 0.5 C 0.5 PO 4 nano-composite shows specific capacity of 148.42 mAhg−1 with 99% retention at 50 cycles. Impedance spectroscopy reveals that the charge transfer resistance of Li 2 TiO 3.LiNi 0.5 C 0.5 PO 4 and LiNi 0.5 C 0.5 PO 4 are 27.5 and 253 Ω, respectively. Image 1 • The high energy ball milling followed by calcination-microwave sintering drastically enhances Li-ion mobility, the AC conductivity in the order of 10−3 S/cm. • Combination of the monoclinic, cubic phase Li 2 TiO 3 provides Li-ion diffusion one to two orders of magnitude higher than individual one. • Microwave sintered nano-crystalline 950 °C Li 2 TiO 3 incorporated nano-composite (LTO@LNCP) shows better specific capacity of 148.42 mAhg−1 and 99% retention after 50 cycles. [ABSTRACT FROM AUTHOR]

A facile and feasible protocol for the evolution of sensing characteristics of three dissimilar nitrogen-doped graphene (N-G)-based ethanol, methanol, and nitrogen-oxide gas sensors using first-principle calculations. Simulated X-ray diffraction (XRD) investigation demonstrates the sharp peak located at 7.9, 11, 13.8, and 15.4° represents (100), (111), (026), and (012) facets. Electronic properties calculations predict that toxic gas adsorption reduces the charge carrier concentration and induces internal resistance. Thermal properties analyses suggest that the nature of adsorption depends on changes in Gibbs free energy. Charge density and distribution analysis disclose that the adsorption of toxic gases leads to charge transfer between toxic gases and N-G. Mechanical properties analyses predict the mechanical superiority. The N-G's electrical conductivity and resistivity of are 49.95 × 103 Ω/m, and 2 × 10−5 Ω-m respectively. The electrical properties demonstrate that the adsorption of toxic gases would be a reason for the change in electrical conductivity and resistivity. The sensing response of N-G-M in terms of resistivity is 96.04 %. The sensing response of ethanol, NO are 17.12 %, and 5.95 %. Responses of N-G-E, N-G-M, N-G-N″-Z are 0.01, 0.06, 0.14 respectively. • XRD analysis reveals the crystalline nature of considered configurations. • Adsorption of toxic gases over the surface of N-G shows exothermic. • CDD analysis reveals charge transfer between toxic gases and N-G. • The sensing response of N-G-M in terms of resistivity is 96.04 %. [ABSTRACT FROM AUTHOR]

Abstract Bi-filler composites composed of exfoliated graphite (EG) and any one of Al 2 O 3 , BaTiO 3 , ZnO and TiO 2 metallic oxides are fabricated in epoxy matrix to improve microwave absorption properties exclusively in X band. These composites are characterized for their morphology and compositional studies using SEM, Raman spectroscopy and X-rays photoelectron spectroscopy. The strong reflection loss values of −43 dB (99.995% absorption), −25.7 dB (99.731% absorption), −33.9 dB (99.959% absorption) and −46.0 (99.997% absorption) with wide effective bandwidths are successfully achieved by the EG/epoxy composites containing 40 wt% Al 2 O3, 30 wt% BaTiO3, 30 wt% TiO2 and 20 wt% ZnO when the thicknesses are 1.8, 1.6, 1.4 and 1.8 mm, respectively. These absorption performances are attributed to the perfect matching conditions, multiple internal reflections, interface polarizations and defect polarizations. The incorporation of metallic oxides demonstrated improved adhesion and reinforcement efficiency factors, as well as uplifted the values of flexural strength and thermal conductivity of EG/epoxy composites. These properties justifies the potential future of metallic oxide/EG/epoxy composite in microwave absorption applications. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Abstract In this study, exfoliated graphite (EG) was used as filler to enhance the dielectric properties of composites, which are processed through microwave (MW) curing. EG was synthesized through MW irradiation technique. The detailed characterizations of as-synthesized EG were first carried out. Afterwards, the EG reinforced epoxy composites have been synthesized. The dielectric properties of composites as a function of EG content with and without MW heating were measured at a frequency of 2.45 GHz. The 3 wt% EG/epoxy composite shows an increase of about 43 and 81% in dielectric constant and loss factor, respectively. The dielectric properties are found to decrease after MW curing. Finally, the dynamical mechanical analysis was performed for MW cured samples including thermally cured samples. The glass transition temperature and storage modulus are found to improve by about 24 °C and 58%, respectively for MW cured 3 wt% EG/epoxy composite as compared to neat epoxy counterpart. Highlights • The exfoliated graphite (EG) is used as filler in epoxy resin for improving the dielectric properties at 2.45 ± 0.05 GHz. • The dielectric constant (εr') and loss factor (εr'') increase with increasing EG content. • Both the εr' and εr'' of synthesized composites decreases after microwave curing using microwave oven. • The glass transition temperature of MW cured 3wt% EG/epoxy is almost equal to its conventionally cured counterparts for 4 h. • For both conventional and microwave curing methods, the optimum loading of 3wt% EG in epoxy is obtained. [ABSTRACT FROM AUTHOR]

Morphology and electronic bandgap of titania (TiO 2 ) are considered to be the primary factors for determining the photocatalytic efficiency, as they determine the number of active sites for the photocatalytic reactions. In the present study, two different morphologies of TiO 2 (nanosphere and nanorod) with varying Zn and Mn co-doping were synthesized by solvothermal and hydrothermal methods to examine their photocatalytic efficiency by methylene blue degradation. The co-doped photocatalysts were characterized by XRD, XPS, SEM, TEM, Raman, FTIR and UV–vis DRS. Further, a comparison has been made with co-doped TiO 2 nanospheres and TiO 2 nanorods, where Zn, Mn co-doped TiO 2 nanorods show higher photocatalytic activity compared to nanospheres. This higher photocatalytic activity of co-doped TiO 2 is attributed to its polymorphic phases, as they act as heterojunctions for TiO 2 . Further, being 1-D nanostructure, the TiO 2 nanorods exhibit the straight diffusion path for charge carriers, which reduces the recombination possibilities. The obtained results suggest that the photocatalysis efficiency of TiO 2 can be significantly enhanced by tailoring the shape and co-doping concentration, which enforce a new concept for developing the new nanostructures of TiO 2 . [ABSTRACT FROM AUTHOR]

Cost-efficient synthesis of biomass-derived carbon-based adsorbents having high adsorption capacity for wastewater treatment has been reported. Multi-doped carbon fibers (MCFs) derived from pyrolysis of chicken featherfiber (CFF) have been investigated for their adsorption characteristics for organic water-pollutants. Effects of various structural parameters such as microstructure and surface chemical state of the MCFs on their adsorption properties have been investigated. The maximum adsorption capacity of ~ 170 mg/g is observed for the MCF synthesized at the pyrolysis temperature of 600 °C. Correlations between the adsorption capacities of the MCFs with their surface functionalities suggest the sp 2 carbon to be the most active adsorption site. The Weber and Morris diffusion model suggests that surface adsorption and intraparticle diffusion play significant roles during MB adsorption on the MCFs. Further, the adsorption process follows Langmuir isotherms with a monolayer adsorption. Negative change in enthalpy with MB adsorption reveals the exothermic nature of the adsorption process. Furthermore, the MCFs exhibit high stability under aqueous solutions. This, combined with the adsorption studies using real-life wastewater samples, suggests the CFF derived MCFs to be the suitable adsorbents for large-scale wastewater treatment applications. [ABSTRACT FROM AUTHOR]