Wavelength Dependent Graphene Oxide-Based Optical Microfiber Sensor for Ammonia Gas.

Ammonia detection in ambient air is critical, given its implication on the environment and human health. In this work, an optical fiber tapered to a 20 µm diameter and coated with graphene oxide was developed for absorbance response monitoring of ammonia at visible (500-700 nm) and near-infrared wavelength regions (700-900 nm). The morphology, surface characteristics, and chemical composition of the graphene oxide samples were confirmed by a field emission scanning electron microscope, an atomic force microscope, X-ray diffraction, and an energy dispersion X-ray. The sensing performance of the graphene oxide-coated optical microfiber sensor towards ammonia at room temperature revealed better absorbance response at the near-infrared wavelength region compared to the visible region. The sensitivity, response and recovery times at the near-infrared wavelength region were 61.78 AU/%, 385 s, and 288 s, respectively. The sensitivity, response and recovery times at the visible wavelength region were 26.99 AU/%, 497 s, and 192 s, respectively. The selectivity of the sensor towards ammonia was affirmed with no response towards other gases.

High Sensitivity Microfiber Interferometer Sensor in Aqueous Solution.

The need for environmental protection and water pollution control has led to the development of different sensors for determining many kinds of pollutants in water. Ammonia nitrogen presence is an important indicator of water quality in environmental monitoring applications. In this paper, a high sensitivity sensor for monitoring ammonia nitrogen concentration in water using a tapered microfiber interferometer (MFI) as a sensor platform and a broad supercontinuum laser as the light source is realized. The MFI is fabricated to the waist diameter of 8 µm producing a strong interference pattern due to the coupling of the fundamental mode with the cladding mode. The MFI sensor is investigated for a low concentration of ammonia nitrogen in water in the wide wavelength range from 1500-1800 nm with a high-power signal provided by the supercontinuum source. The broad source allows optical sensing characteristics of the MFI to be evaluated at four different wavelengths (1505, 1605, 1705, and 1785 nm) upon exposure towards various ammonia nitrogen concentrations. The highest sensitivity of 0.099 nm/ppm that indicates the wavelength shift is observed at 1785 nm operating wavelength. The response is linear in the ammonia nitrogen range of 5-30 ppm with the best measurement resolution calculated to be 0.5 ppm. The low concentration ammonia nitrogen detected by the MFI in the unique infrared region reveals the potential application of this optical fiber-based sensor for rivers and drinking water monitoring.

Cellulose acetate beads modified with cadmium sulfide and Methylene blue for adsorbent-assisted photoelectrochemical detection of copper(II) ions.

A multi-functional hybrid of cellulose acetate with cadmium sulfide and Methylene blue (CA/CdS/MB) in a bead composition was synthesized and investigated as a photosensor-adsorbent for the rapid, selective, and sensitive detection, and adsorption of Cu(II) ions. These hybrid CA-modified beads are composed of multiple adsorption active sites and possess a surface area of 58 cm2 g-1. They are an efficient adsorbent with a maximum adsorption capacity of 0.57 mg g-1. Photoelectrochemical (PEC) detection of Cu(II) was accomplished by modifying the beads on a glassy carbon electrode. The beads containing 20 mmol of sulfur displayed the widest linear analytical range (0.1-290 nM) and the lowest detection limit (16.9 nM) for Cu(II) with high selectivity and reliable reproducibility. The successful application of the beads has provided a new insight for the selection of a responsive photoactive material for a PEC assay, as well as an effective adsorbent material for Cu(II) ions. Graphical abstract A multi-functional hybrid of cellulose acetate with cadmium sulfide and Methylene blue (CA/CdS/MB) in a bead composition was synthesized and investigated as a photosensor-adsorbent for the rapid, selective and sensitive detection and adsorption of Cu(II) ions.

Optical and Thermal Properties of Laser-Ablated Platinum Nanoparticles Graphene Oxide Composite.

Platinum nanoparticles were synthesized in graphene oxide aqueous solution using a laser ablation technique to investigate the effect of optical linear, nonlinear and thermal properties of platinum-graphene oxide nanocomposite solution. The samples were prepared with different ablation times. The platinum nanoparticles that formed a spherical shape on the surface of graphene oxide solution were authenticated using UV-visible spectrum and transmission electron microscopy patterns. The particle size decreased with increasing ablation time, and the concentration and volume fraction of samples were increased. To obtain the optical linear, nonlinear and thermal properties of platinum-graphene oxide nanocomposite solution, UV-visible spectroscopy, Z-scan, thermal lens and photoacoustic techniques were used. Consequently, the linear and nonlinear refractive indices increased with an increase in the volume fraction of platinum nanoparticles. It was observed from the spatial self-phase modulation patterns that, the optical nonlinear property of the graphene oxide was enhanced in the presence of platinum nanoparticles, and the nonlinearity increased with an increase in the volume fraction of platinum nanoparticles inside the graphene oxide solution. The thermal diffusivity and thermal effusivity of platinum nanoparticles graphene oxide were measured using a thermal lens and photoacoustic methods, respectively. The thermal diffusivity and thermal effusivity of samples were in the range of 0.0341 × 10-5 m2/s to 0.1223 × 10-5 m2/s and 0.163 W s1/2 cm-2 K-1 to 0.3192 W s1/2 cm-2 K-1, respectively. Consequently, the platinum enhanced the optical and thermal properties of graphene oxide.

Gold-silver@TiO2 nanocomposite-modified plasmonic photoanodes for higher efficiency dye-sensitized solar cells.

In the present investigation, gold-silver@titania (Au-Ag@TiO2) plasmonic nanocomposite materials with different Au and Ag compositions were prepared using a simple one-step chemical reduction method and used as photoanodes in high-efficiency dye-sensitized solar cells (DSSCs). The Au-Ag incorporated TiO2 photoanode demonstrated an enhanced solar-to-electrical energy conversion efficiency of 7.33%, which is ∼230% higher than the unmodified TiO2 photoanode (2.22%) under full sunlight illumination (100 mW cm-2, AM 1.5G). This superior solar energy conversion efficiency was mainly due to the synergistic effect between the Au and Ag, and their surface plasmon resonance effect, which improved the optical absorption and interfacial charge transfer by minimizing the charge recombination process. The influence of the Au-Ag composition on the overall energy conversion efficiency was also explored, and the optimized composition with TiO2 was found to be Au75-Ag25. This was reflected in the femtosecond transient absorption dynamics in which the electron-phonon interaction in the Au nanoparticles was measured to be 6.14 ps in TiO2/Au75:Ag25, compared to 2.38 ps for free Au and 4.02 ps for TiO2/Au100:Ag0. The slower dynamics indicates a more efficient electron-hole separation in TiO2/Au75:Ag25 that is attributed to the formation of a Schottky barrier at the interface between TiO2 and the noble metal(s) that acts as an electron sink. The significant boost in the solar energy conversion efficiency with the Au-Ag@TiO2 plasmonic nanocomposite showed its potential as a photoanode for high-efficiency DSSCs.

Synthesis and Characterization of Polyaniline/Graphene Composite Nanofiber and Its Application as an Electrochemical DNA Biosensor for the Detection of Mycobacterium tuberculosis.

This article describes chemically modified polyaniline and graphene (PANI/GP) composite nanofibers prepared by self-assembly process using oxidative polymerization of aniline monomer and graphene in the presence of a solution containing poly(methyl vinyl ether-alt-maleic acid) (PMVEA). Characterization of the composite nanofibers was carried out by Fourier transform infrared (FTIR) and Raman spectroscopy, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). SEM images revealed the size of the PANI nanofibers ranged from 90 to 360 nm in diameter and was greatly influenced by the proportion of PMVEA and graphene. The composite nanofibers with an immobilized DNA probe were used for the detection of Mycobacterium tuberculosis by using an electrochemical technique. A photochemical indicator, methylene blue (MB) was used to monitor the hybridization of target DNA by using differential pulse voltammetry (DPV) method. The detection range of DNA biosensor was obtained from of 10-6-10-9 M with the detection limit of 7.853 × 10-7 M under optimum conditions. The results show that the composite nanofibers have a great potential in a range of applications for DNA sensors.

Electrochemical detection of uric acid via uricase-immobilized graphene oxide.

Measurement of the uric acid level in the body can be improved by biosensing with respect to the accuracy, sensitivity and time consumption. This study has reported the immobilization of uricase onto graphene oxide (GO) and its function for electrochemical detection of uric acid. Through chemical modification of GO using 1-ethyl-3-(dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysulfosuccinimide (NHS) as cross-linking reagents, the enzyme activity of the immobilized uricase was much comparable to the free enzyme with 88% of the activity retained. The modified GO-uricase (GOU) was then subjected to electrocatalytic detection of uric acid (UA) via cyclic voltammetry (CV). For that reason, a glassy carbon electrode (GCE) was modified by adhering the GO along with the immobilized uricase to facilitate the redox reaction between the enzyme and the substrate. The modified GOU/GCE outperformed a bare electrode through the electrocatalytic activity with an amplified electrical signal for the detection of UA. The electrocatalytic response showed a linear dependence on the UA concentration ranging from 0.02 to 0.49 mM with a detection limit of 3.45 µM at 3σ/m. The resulting biosensor also exhibited a high selectivity towards UA in the presence of other interference as well as good reproducibility.

A gold nanorod-based localized surface plasmon resonance platform for the detection of environmentally toxic metal ions.

Gold nanorods (Au NRs) are elongated nanoparticles with unique optical properties which depend on their shape anisometry. The Au NR-based longitudinal localized surface plasmon resonance (longitudinal LSPR) band is very sensitive to the surrounding local environment and upon the addition of target analytes, the interaction between the analytes and the surface of the Au NRs leads to a change in the longitudinal LSPR band. This makes it possible to devise Au NR probes with application potential to the detection of toxic metal ions with an improved limit of detection, response time, and selectivity for the fabrication of sensing devices. The effective surface modification of Au NRs helps in improving their selectivity and sensitivity toward the detection of toxic metal ions. In this review, we discuss different methods for the preparation of surface modified Au NRs for the detection of toxic metal ions based on the LSPR band of the Au NRs and the types of interactions between the surface of Au NRs and metal ions. We summarize the work that has been done on Au NR-based longitudinal LSPR detection of environmentally toxic metal ions, sensing mechanisms, and the current progress in various modified Au NR-based longitudinal LSPR sensors for toxic metal ions. Finally, we discuss the applications of Au NR-based longitudinal LSPR sensors to real sample analysis and some of the future challenges facing longitudinal LSPR-based sensors for the detection of toxic metal ions toward commercial devices.

Hematite nanoparticles-modified electrode based electrochemical sensing platform for dopamine.

Hematite (α-Fe2O3) nanoparticles were synthesized by the solid transformation of ferrous hydroxide and ferrihydrite in hydrothermal condition. The as-prepared α-Fe2O3 nanoparticles were characterized by UV-vis, PL, XRD, Raman, TEM, AFM, FESEM, and EDX analysis. The experimental results indicated the formation of uniform hematite nanoparticles with an average size of 45 nm and perfect crystallinity. The electrochemical behavior of a GC/α-Fe2O3 electrode was studied using CV and EIS techniques with an electrochemical probe, [Fe(CN)6](3-/4-) redox couple. The electrocatalytic activity was investigated toward DA oxidation in a phosphate buffer solution (pH 6.8) by varying different experimental parameters. The chronoamperometric study showed a linear response in the range of 0-2 µM with LoD of 1.6 µM for DA. Square wave voltammetry showed a linear response in the range of 0-35 µM with LoD of 236 nM for DA.

Fixed-bed adsorption studies of endocrine-disrupting compounds from water by using novel calcium-based metal-organic frameworks.

The presence of emerging water pollutants such as endocrine-disrupting compounds (EDCs), including 17-ethynylestradiol (EE2), bisphenol A (BPA), and perfluorooctanoic acid (PFOA), in contaminated water sources poses significant environmental and health challenges. This study aims to address this issue by investigating the efficiency of novel calcium-based metal-organic frameworks, known as mixed-linker calcium-based metal-organic frameworks (Ca-MIX), in adsorbing these endocrine-disrupting compounds. This study analyzed the influence of influent concentration, bed height, and flow rate on pollutant removal, with bed height emerging as a crucial factor. From the breakthrough curves, it was determined that the column maximum adsorption capacities followed the order of 17-ethynylestradiol (101.52 µg/g; 40%) > bisphenol A (99.07 µg/g; 39%) > perfluorooctanoic acid (81.28 µg/g; 32%). Three models were used to predict the adsorption process, with the Yan model outperforming the other models. This suggests the potential of mixed-linker calcium-based metal-organic frameworks for removing endocrine-disrupting compounds from water, using the Yan model as an effective predictor. Overall, this study provides valuable insights for the development of effective water treatment methods using mixed-linker calcium-based metal-organic frameworks to remove endocrine-disrupting compounds from contaminated water sources.

Growth-control of hexagonal CdS-decorated ZnO nanorod arrays with low-temperature preheating treatment for improved properties and efficient photoelectrochemical applications.

The limitations of oxide semiconductor-based solar cells in achieving high energy conversion efficiencies have prompted incessant research efforts towards the creation of efficient heterostructures. Despite its toxicity, no other semiconducting material can fully replace CdS as a versatile visible light-absorbing sensitizer. Herein, we explore the aptness of preheating treatment in the successive ionic layer adsorption and reaction (SILAR) deposition technique and improve the understanding of the principle and the effects of a controlled growth environment on thus-formed CdS thin films. Single hexagonal phases of nanostructured cadmium sulfide (CdS)-sensitized zinc oxide nanorods arrays (ZnO NRs) have been developed without the support of any complexing agent. The influences of film thickness, cationic solution pH and post-thermal treatment temperature on the characteristics of binary photoelectrodes have been investigated experimentally. Interestingly, the preheating-assisted deposition of CdS, which is rarely applied for the SILAR technique, resulted in improved photoelectrochemical performance similar to the post-annealing effect. The X-ray diffraction pattern revealed that optimized ZnO/CdS thin films were polycrystalline with high crystallinity. Examination of the morphology of the fabricated films via field emission scanning electron microscopy showed that film thickness and medium pH altered the growth mechanism of nanoparticles, thereby changing their particle sizes, which had a significant influence on the film's optical behavior. The effectiveness of CdS as a photosensitizer and the band edge alignment for ZnO/CdS heterostructures were evaluated using ultra-violet visible spectroscopy. Facile electron transfer in the binary system as evidenced in electrochemical impedance spectroscopy Nyquist plots, therefore, promotes higher photoelectrochemical efficiencies from 0.40% to 4.30% under visible light illumination as compared with the pristine ZnO NRs photoanode.

PES-Ag3PO4/g-C3N4 Mixed Matrix Film Photocatalyst for Degradation of Methyl Orange Dye.

In the present study, we explored the effectiveness of PES-Ag3PO4/g-C3N4 film photocatalyst in degrading methyl orange dye under visible light irradiation. The PES-Ag3PO4/g-C3N4 film photocatalyst was prepared via a non-solvent-induced phase inversion process and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), laser scanning microscopy (LSM), X-ray photoelectron spectra (XPS), UV-diffuse reflectance (DRS), and water contact angle. The incorporation of the Ag3PO4/g-C3N4 composite into the PES matrix improved the pristine PES film's hydrophilicity, as evidenced by the reduction of water contact angle from 79.03° to 54.33° for a film containing 15 wt % of Ag3PO4/g-C3N4 composite. The film's photoactivity showed that 13 wt % was the best loading of Ag3PO4/g-C3N4 composite, and the degradation performance was maintained up to three cycles. The •O2- and h+ were the predominant species responsible for the methyl orange degradation.

Enhanced capacitive performance of cathodically reduced titania nanotubes pulsed deposited with Mn2O3 as supercapacitor electrode.

A facile and simple pulse electrodeposition method was employed to deposit Mn2O3 nanoparticles on cathodically reduced titania nanotubes (R-TNTs) at different deposition time in the range of 3-15 min to investigate the influence of mass loading of Mn2O3 on the electrochemical performance of Mn2O3/R-TNTs nanocomposite for supercapacitor application. Mn2O3 nanoparticles were deposited on circumference of R-TNTs as well as in the nanotubes as revealed by FESEM images for all the deposited time. XPS result confirmed the presence of MnO2 (Mn4+) and MnO (Mn2+) on the Mn2O3/R-TNTs composite which provide pseudocapacitive behaviour for the electrode. Mass loading of Mn2O3 increased linearly with deposition time as confirmed by EDX analysis. The sample deposited for 12 min exhibits the highest areal capacitance of 51 mF cm-2 (which is 22 times enhancement over R-TNTs) at a current density of 0.1 mA cm-2 and specific capacitance of 325 F g-1 at 6 A g-1. The sample also show a high-rate capability by retaining 80% of its capacitance even at higher current density of 30 A g-1. Interestingly, it retained 98% of the capacitance over 5000 charge discharge cycles at 10 A g-1 after initial drop to 95% at 200th cycles suggesting an excellent long-term chemical stability. A considerably low equivalent series resistance (ESR) and charge transfer resistance (R ct) of 9.6 Ω and 0.4 Ω respectively was deduced from electrochemical impedance spectroscopy (EIS) analysis indicating good conductivity and improved charge transfer efficiency of Mn2O3/R-TNTs nanocomposite.

Preparations, Properties, and Applications of Polyaniline and Polyaniline Thin Films-A Review.

Polyaniline (PANI) is a famous conductive polymer, and it has received tremendous consideration from researchers in the field of nanotechnology for the improvement of sensors, optoelectronic devices, and photonic devices. PANI is doped easily by different acids and dopants because of its easy synthesis and remarkable environmental stability. This review focuses on different preparation processes of PANI thin film by chemical and physical methods. Several features of PANI thin films, such as their magnetic, redox, and antioxidant, anti-corrosion, and electrical and sensing properties, are discussed in this review. PANI is a highly conductive polymer. Given its unique properties, easy synthesis, low cost, and high environmental stability in various applications such as electronics, drugs, and anti-corrosion materials, it has attracted extensive attention. The most important PANI applications are briefly reviewed at the end of this review.

Synthesis and Optimization of Mesoporous Silica Nanoparticles for Ruthenium Polypyridyl Drug Delivery.

The ruthenium polypyridyl complex [Ru(dppz)2PIP]2+ (dppz: dipyridophenazine, PIP: (2-(phenyl)-imidazo[4,5-f ][1,10]phenanthroline), or Ru-PIP, is a potential anticancer drug that acts by inhibiting DNA replication. Due to the poor dissolution of Ru-PIP in aqueous media, a drug delivery agent would be a useful approach to overcome its limited bioavailability. Mesoporous silica nanoparticles (MSNs) were synthesized via a co-condensation method by using a phenanthrolinium salt with a 16 carbon length chain (Phen-C16) as the template. Optimization of the synthesis conditions by Box-Behnken design (BBD) generated MSNs with high surface area response at 833.9 m2g-1. Ru-PIP was effectively entrapped in MSNs at 18.84%. Drug release profile analysis showed that Ru-PIP is gradually released, with a cumulative release percentage of approximately 50% at 72 h. The release kinetic profile implied that Ru-PIP was released from MSN by diffusion. The in vitro cytotoxicity of Ru-PIP, both free and MSN-encapsulated, was studied in Hela, A549, and T24 cancer cell lines. While treatment of Ru-PIP alone is moderately cytotoxic, encapsulated Ru-PIP exerted significant cytotoxicity upon all the cell lines, with half maximal inhibitory concentration (IC50) values determined by MTT (([3-(4,5-dimethylthiazol-2-yl)-2,5-dephenyltetrazolium bromide]) assay at 48 h exposure substantially decreasing from >30 µM to <10 µM as a result of MSN encapsulation. The mechanistic potential of cytotoxicity on cell cycle distribution showed an increase in G1/S phase populations in all three cell lines. The findings indicate that MSN is an ideal drug delivery agent, as it is able to sustainably release Ru-PIP by diffusion in a prolonged treatment period.

Selective and sensitive visible-light-prompt photoelectrochemical sensor of Cu2+ based on CdS nanorods modified with Au and graphene quantum dots.

Nowadays, increasing the risk for copper leaching into the drinking water in homes, hotels and schools has become unresolved issues all around the countries such as Canada, the United States, and Malaysia. The leaching of copper in tap water is due to a combination of acidic water, damaged pipes, and corroded plumbing fixtures. To remedy this global problem, a triple interconnected structure of CdS/Au/GQDs was designed as a photo-to-electron conversion medium for a real time and selective visible-light-prompt photoelectrochemical (PEC) sensor for Cu2+ ions in real water samples. The synergistic interaction of the CdS/Au/GQDs enabled the smooth transportation of charge carriers to the charge collector and provided a channel to inhibit the charge recombination reaction. Thus, a detection limit of 2.27 nM was obtained, which is 10,000 fold lower than that of WHO's Guidelines for Drinking-water Quality (∼30 µM). The photocurrent reduction was negligible after 30 days of storage under ambient conditions, suggesting the high stability of photoelectrode. Moreover, the real-time monitoring of Cu2+ ions in real samples was performed with satisfactory results, confirming the capability of the investigated photoelectrode as the most practical detector for trace amounts of Cu2+ ions.

Ultrasonic Assisted Synthesis of Size-Controlled Cu-Metal-Organic Framework Decorated Graphene Oxide Composite: Sustainable Electrocatalyst for the Trace-Level Determination of Nitrite in Environmental Water Samples.

Excess levels of nitrite ion in drinking water interact with amine functionalized compounds to form carcinogenic nitrosamines, which cause stomach cancer. Thus, it is indispensable to develop a simple protocol to detect nitrite. In this paper, a Cu-metal-organic framework (Cu-MOF) with graphene oxide (GO) composite was synthesized by ultrasonication followed by solvothermal method and then fabricated on a glassy carbon (GC) electrode for the sensitive and selective determination of nitrite contamination. The SEM image of the synthesized Cu-MOF showed colloidosome-like structure with an average size of 8 µm. Interestingly, the Cu-MOF-GO composite synthesized by ultrasonic irradiation followed by solvothermal process produce controlled size of 3 µm colloidosome-like structure. This was attributed to the formation of an exfoliated sheet-like structure of GO by ultrasonication in addition to the obvious influence of GO providing the oxygen functional groups as a nucleation node for size-controlled growth. On the other hand, the composite prepared without ultrasonication exhibited 6.6 µm size agglomerated colloidosome-like structures, indicating the crucial role of ultrasonication for the formation of size-controlled composites. XPS results confirmed the presence of Cu(II) in the as-synthesized Cu-MOF-GO based on the binding energies at 935.5 eV for Cu 2p3/2 and 955.4 eV for Cu 2p1/2. The electrochemical impedance studies in [Fe(CN)6]3-/4- redox couple at the composite fabricated electrode exhibited more facile electron transfer than that with Cu-MOF and GO modified electrodes, which helped to utilize Cu-MOF-GO for trace level determination of nitrite in environmental effluent samples. The Cu-MOF-GO fabricated electrode offered a superior sensitive platform for nitrite determination than the Cu-MOF and GO modified electrodes demonstrating oxidation at less positive potential with enhanced oxidation current. The present sensor detects nitrite in the concentration range of 1 × 10-8 to 1 × 10-4 M with the lowest limit of detection (LOD) of 1.47 nM (S/N = 3). Finally, the present Cu-MOF-GO electrode was successfully exploited for nitrite ion determination in lake and dye contaminated water samples.

Co-pyrolysis of polyethylene with products from thermal decomposition of brominated flame retardants.

Co-pyrolysis of brominated flame retardants (BFRs) with polymeric materials prevails in scenarios pertinent to thermal recycling of bromine-laden objects; most notably the non-metallic fraction in e-waste. Hydro-dehalogenation of aromatic compounds in a hydrogen-donating medium constitutes a key step in refining pyrolysis oil of BFRs. Chemical reactions underpinning this process are poorly understood. Herein, we utilize accurate density functional theory (DFT) calculations to report thermo-kinetic parameters for the reaction of solid polyethylene, PE, (as a surrogate model for aliphatic polymers) with prime products sourced from thermal decomposition of BFRs, namely, HBr, bromophenols; benzene, and phenyl radical. Facile abstraction of an ethylenic H by Br atoms is expected to contribute to the formation of abundant HBr concentrations in practical systems. Likewise, a relatively low energy barrier for aromatic Br atom abstraction from a 2-bromophenol molecule by an alkyl radical site, concurs with the reported noticeable hydro-debromination capacity of PE. Pathways entailing a PE-induced bromination of a phenoxy radical should be hindered in view of high energy barrier for a Br transfer into the para position of the phenoxy radical. Adsorption of a phenoxy radical onto a Cu(Br) site substituted at the PE chain affords the commonly discussed PBDD/Fs precursor of a surface-bounded bromophenolate adduct. Such scenario arises due to the heterogeneous integration of metals into the bromine-rich carbon matrix in primitive recycling of e-waste and their open burning.

Performance Analysis of Jatropha Oil-Based Polyurethane Acrylate Gel Polymer Electrolyte for Dye-Sensitized Solar Cells.

Biobased polymers are useful materials in substituting conventional petroleum-derived polymers because of their good properties, ready availability, and abundance in nature. This study reports a new jatropha oil-based gel polymer electrolyte (GPE) for use in dye-sensitized solar cells (DSSCs). The GPE was prepared by mixing jatropha oil-based polyurethane acrylate (PUA) with different concentrations of lithium iodide (LiI). The GPE was characterized by infrared spectroscopy, thermal analysis, lithium nuclear magnetic resonance analysis, electrochemical analysis, and photocurrent conversion efficiency. The highest room-temperature ionic conductivity of 1.88 × 10-4 S cm-1 was obtained at 20 wt % of LiI salt. Additionally, the temperature-dependent ionic conductivity of the GPE exhibited Arrhenius behavior with an activation energy of 0.42 eV and a pre-exponential factor of 1.56 × 103 S cm-1. The electrochemical stability study showed that the PUA GPE was stable up to 2.35 V. The thermal stability of the gel electrolyte showed an improvement after the addition of the salt, suggesting a strong intermolecular interaction between PUA and Li, which leads to polymer-salt complexation, as proven by Fourier transform infrared spectroscopy analysis. A DSSC has been assembled using the optimum ionic conductivity gel electrolyte which indicated 1.2% efficiency under 1 sun condition. Thus, the jatropha oil-based GPE demonstrated favorable properties that make it a promising alternative to petroleum-derived polymer electrolytes in DSSCs.

In vitro apatite mineralization and heat generation of magnetite-reduced graphene oxide nanocomposites for hyperthermia treatment.

Nanocomposites of magnetite (Fe3O4) and reduced graphene oxide (rGO) generate heat under an alternating magnetic field and therefore have potential applications as thermoseeds for cancer hyperthermia treatment. However, the properties of such nanocomposites as biomaterials have not been sufficiently well characterized. In this study, the osteoconductivity of Fe3O4-rGO nanocomposites of various compositions was evaluated in vitro in terms of their apatite-forming ability in simulated body fluid (SBF). Furthermore, the heat generation of the nanocomposites was measured under an alternating magnetic field. The apatite-forming ability in SBF improved as the Fe3O4 content in the nanocomposite was increased. As the Fe3O4 content was increased, the nanocomposite not only rapidly raised the surrounding temperature to approximately 100 °C, but the specific absorption rate also increased. We assumed that the ionic interaction between the Fe3O4 and rGO was enhanced and that Brown relaxation was suppressed as the proportion of rGO in the nanocomposite was increased. Consequently, a high content of Fe3O4 in the nanocomposite was effective for improving both the osteoconductivity and heat generation characteristics for hyperthermia applications.