Search

We report a cobalt ferrite nanorods (CFO NRs) based magnetically tunable spur-line notch filter where vertically aligned CFO NRs has been grown on silver nanoparticles coated silicon substrate. The CFO NRs are coupled with high frequency spur-line bandstop filter in flip-chip configuration and the device showed excellent tunable microwave properties in the presence of a low bias magnetic field. The center frequency of the tunable filter is ~16.4 GHz which is shifted to ~14.9 GHz with ~8.7% tunability by applying bias magnetic field ~320 Oe. The magnetic field tuning of the center frequency is explained on the basis of the change in permeability value of the CFO NRs with bias magnetic field as the NRs are used in the partially magnetized state. For validation, permeability value is also calculated by using numerical equations. The experimental reflection of the device has been supported with a simulation using CST microwave studio software. FIG. (a) Schematic of the spur-line bandstop filter design with CFO NRs in the flip-chip geometry (b) Measured transmission characteristics of spur-line bandstop filter and (c) Shift in the center frequency with bias magnetic field. Image 1 • A novel two step approach for the fabrication of cobalt ferrite nanorods (CFO NRs) without using any template. • Demonstration of spur-line based magnetically tunable bandstop filter in the flip-chip configuration using CFO NRs. • A great tuning (~8.7%) is achieved in the presence of low bias magnetic field. [ABSTRACT FROM AUTHOR]

In recent years, triboelectric nanogenerator (TENG) has been attracting lots of attention for harvesting electrical energy from mechanical energy, because of its simplicity in designing, cost-effectiveness, and high output power. In the present trend, the performance of TENG is improved mainly by surface modification using complex techniques. In the present work, we have demonstrated enhanced triboelectrification between polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE) by incorporating ZnO nanorods into PVDF polymer. The fabricated ZnO-PVDF/PTFE based TENG showed 21% enhanced output voltage and 60% enhanced short-circuit current in comparison to PVDF/PTFE based TENG with an instantaneous output power density of ∼10.6 μW/cm2. The increase in triboelectrification comes not only from the enhancement in β-phase content, which leads to increase polarizability, but also from the enhancement in surface roughness, hydrophobicity, and a decrease in the work function of PVDF after incorporating ZnO nanorods. Image 1079 • Achieved 65.6% more instantaneous output power in nanocomposite film as compared to bare film based TENG. • Surface roughness, polarizability and hydrophobicity plays an important role in the performance of TENG. • Simple yet effective way of enhancing the triboelectric property of ferroelectric film (PVDF). • The localised ferroelectric property of PVDF was studied using PFM. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Oil to water phase conversion of superparamagnetic CoFe 2 O 4 nanoparticles. • Novel mechanochemical ligand exchange method was used. • For rapid and large scale production of water dispersible biocompatible MNPs. • Application in magnetic hyperthermia for treating the cancer cells is demonstrated. Abstract We report the hydrothermal synthesis of uniform size (∼6 nm) oleic acid capped CoFe 2 O 4 (OA-CoFe 2 O 4) nanoparticles. These OA-CoFe 2 O 4 nanoparticles were initially hydrophobic and not dispersible in water which were transformed into hydrophilic nanoparticles by modifying their surface with citric acid using a rapid mechanochemical ligand exchange process, which makes CoFe 2 O 4 nanoparticles stable colloidal solution in water. The synthesized citric acid coated CoFe 2 O 4 (CA-CoFe 2 O 4) nanoparticles show a high enough and stable zeta potential over 120 days. CA-CoFe 2 O 4 nanoparticles exhibited high biocompatibility under in vitro cell studies. The specific absorption rate (SAR) of the CA-CoFe 2 O 4 nanoparticles was measured by induction heating studies. Upon the exposure of AC external magnetic field, the viability of cancer cells was reduced considerably, suggesting efficient potentiality of these CA-CoFe 2 O 4 nanoparticles for Magnetic Hyperthermia Applications. Present mechanochemical ligand exchange method is proposed as an efficient method for large scale production of biocompatible and water dispersible magnetic oxide nanoparticles for Magnetic Hyperthermia Applications. [ABSTRACT FROM AUTHOR]

Graphical abstract Bismuth sulfide (Bi 2 S 3) has been synthesized in the morphology of hierarchical nanostructures by facile hydrothermal method. The photocatalytic efficiency of Bi 2 S 3 nanostructures has been checked for the degradation of MB, RhB single dye solution and their binary mixture and compared with commercial TiO 2 (Degussa P25) sample under visible light illumination. The degradation rate of RhB and MB is enhanced by ∼8 times and ∼3 times in their binary solution as compared to that in single dye solution and increased by ∼14 times than that of Degussa P25 for both RhB and MB degradation in the binary solution, respectively. This remarkable improvement in the photocatalytic activity of Bi 2 S 3 is attributed to the faster separation of charge carriers at the interface due to the favourable LUMO and HOMO alignment of RhB and MB with band levels of Bi 2 S 3 in the RhB-MB-Bi 2 S 3 trio system. The photocatalytic degradation study of colourless contaminants, p-chlorophenol (CP), p-nitrophenol (NP) and their mixture (CP-NP) is also investigated. The degradation rate of NP is observed to be highest in the single solution, whereas, the degradation rate of both CP and NP is found to decrease in binary mixture solution in comparison to their individual solution. Highlights • Hierarchical nanostructures of Bi 2 S 3 have been synthesized by hydrothermal method. • Utilized Bi 2 S 3 for the photodegradation of MB, RhB and their binary solution. • Demonstrated the enhanced photocatalytic activity in RhB-MB-Bi 2 S 3 trio system. • Degradation of p-chlorophenol (CP), p-nitrophenol (NP) and CP-NP over Bi 2 S 3. • Achieved highest degradation rate of NP among all phenolic compounds. Abstract Hierarchical nanostructures of bismuth sulfide (Bi 2 S 3) have been synthesized by a facile hydrothermal method. The potentiality of Bi 2 S 3 hierarchical nanostructures for the photocatalytic degradation of Rhodamine B (RhB), Methylene blue (MB) and the mixture of RhB-MB organic dyes have been demonstrated and compared with commercial TiO 2 (Degussa P25) sample under visible light illumination. The degradation efficiency of Bi 2 S 3 and Degussa P25 is found to be higher in the single as well as in the binary dye solution for MB degradation as compared to RhB degradation. Furthermore, the degradation rate of RhB and MB is enhanced by ∼8 times and ∼3 times in their binary solution as compared to that in single dye solution. Whereas, Bi 2 S 3 has demonstrated ∼14 times higher degradation rate of both RhB and MB in their binary solution than that of Degussa P25 for RhB and MB degradation in the binary solution under visible light exposure, respectively. Interestingly, Bi 2 S 3 nanostructures has exhibited larger improvement in the degradation efficiency for RhB in its binary solution which is attributed to the faster separation of photogenerated charge carriers due to the proper alignments between the molecular orbits of dyes and band level positions of Bi 2 S 3 in RhB-MB-Bi 2 S 3 heterogenous system. The photocatalytic degradation study of colourless contaminants, p-chlorophenol (CP), p-nitrophenol (NP) and their mixture (CP-NP) is also investigated in the presence of Bi 2 S 3 nanoflowers. Among the phenolic compounds, the degradation rate of NP is observed to be highest in the single solution. However, the degradation rate of both CP and NP is found to decrease in binary mixture solution in comparison to their individual solution. A possible mechanism for the enhanced photodegradation of RhB-MB dye mixture based on the active species trapping experiment has been proposed. [ABSTRACT FROM AUTHOR]

Effect of intrinsic strain on the optical band gap of single phase Cu2ZnSnS4 (CZTS) nanostructures have been studied which have been synthesized by three different methods: ultrasonic assisted vapour deposition (UACVD), microwave and solvothermal in a single step process. X-ray diffraction and Raman studies revealed the formation of single phase CZTS nanostructures. The nanostructured film deposited by UACVD exhibited crystallite size ~20nm, optical band gap of 1.4eV with intrinsic strain 5.2×10-4 whereas the nanostructures grown by solvothermal method have smaller crystal size (~7nm) with higher intrinsic strain (~52.9×10-4). With increases in the crystallite size from 7nm to 20nm, the optical band gap of CZTS nanoparticles decreases from 1.72eV to 1.4eV. The variation in the optical band gaps of the CZTS nanostructures cannot be fully accounted to the variation in the size of nanoparticles and it has been attributed to the intrinsic strain present in the CZTS nanostructures. [ABSTRACT FROM AUTHOR]

A visible light active photocatalyst, Ag/TiO 2 /MWCNT was synthesized by loading of Ag nanoparticles onto TiO 2 /MWCNT nanocomposite. The photocatalytic activity of Ag/TiO 2 /MWCNT ternary nanocomposite was evaluated for the degradation of methylene blue dye under UV and visible light irradiation. Ag/TiO 2 /MWCNT ternary nanocomposite exhibits (~9 times) higher photocatalytic activity than TiO 2 /MWCNT and (~2 times) higher than Ag/TiO 2 binary nanocomposites under visible light irradiation. The enhancement in the photocatalytic activity is attributed to the synergistic effect between Ag nanoparticles and MWCNT, which enhance the charge separation efficiency by Schottky barrier formation at Ag/TiO 2 interface and role of MWCNT as an electron reservoir. Effect of different scavengers on the degradation of methylene blue dye in the presence of catalyst has been investigated to find the role of photogenerated electrons and holes. Simultaneously, the Ag/TiO 2 /MWCNT shows excellent photocatalytic stability. This work highlights the importance of Ag/TiO 2 /MWCNT ternary nanocomposite as highly efficient and stable visible-light-driven photocatalyst for the degradation of organic dyes. [ABSTRACT FROM AUTHOR]

Single phase cobalt ferrite (CoFe 2 O 4 , CFO) nanoparticles of a controlled size (∼6 nm) exhibiting superparamagnetic properties have been synthesized by hydrothermal technique using oleic acid (OA) as surfactant. The oleic acid coated CFO nanoparticles are stable in non-polar organic media, such as hexane but are not well dispersible in water. The surface of these nanoparticles has been further modified by citric acid using ligand exchange process, which makes CFO nanoparticles more stable colloidal solution in water. Citric acid coated CFO nanoparticles exhibits high dispersibility in water, high zeta potential, very low coercivity and moderate saturation magnetization. Biocompatibility of these CFO nanoparticles is demonstrated through cytotoxicity test in L929 cell line. [ABSTRACT FROM AUTHOR]

Single domain CoFe 2 O 4 nanoparticles with different amount of defects/strain have been synthesized by varying the growth temperature in the hydrothermal method. Nanoparticles grown at lower temperature are of larger size and exhibit more planar defects and oxygen vacancies as compared to nanoparticles grown at higher temperatures which are of smaller sizes and exhibit less planar defects and oxygen vacancies. The nanoparticles with larger amount of defects also possess a higher value of intrinsic strain as compared to nanoparticles with fewer defects. The presence of intrinsic strain in the nanoparticles is found to shift the cationic distribution at the tetrahedral and octahedral sites. The saturation magnetization ( M s ) of the nanoparticles is found to depend upon both the intrinsic strain and size of the nanoparticles. The M s increases with the decrease in the nanoparticles size from 32 nm to 20 nm, and this is correlated to the inverse of spin canting effect due to decrease in the intrinsic strain which leads to shifting of Co 2+ ions from tetrahedral to octahedral sites. However, with further decrease in the size of the nanoparticles (16 nm), the size effect dominates over the strain effect leading to decrease in M s . The coercivity is found to be higher in the nanoparticles with larger amount of defects/strain and has been attributed to strain induced strong spin canting and pinning due to defect sites. The variation of coercivity with particle size ( D ) exhibits deviation from D 3/2 dependence for the nanoparticles with larger amount of strain/defects. [ABSTRACT FROM AUTHOR]

CdS nanorods decorated with CoFe 2 O 4 (CFO) nanoparticles have been synthesized by using a facile soft chemical method. The surface of the nanorods was carefully functionalized with citrate ions to attach the CFO nanoparticles. The CFO nanoparticles decorated CdS nanorods were found to exhibit enhanced visible light driven photocatalytic activity for the degradation of methylene blue dye as compared to CdS and CFO nanostructures. The enhancement in the photocatalytic activity is attributed to the formation of heterojunction between the CdS and CFO which significantly suppresses the recombination of the photogenerated charge carriers. Also, due to the magnetic behavior of CFO this coupled nanostructure can be easily separable from the aqueous solution by applying an external magnetic field. [ABSTRACT FROM AUTHOR]

Reduced graphene oxide (RGO) coupled CdS/ZnO core/shell nanorods have been synthesized using a soft chemical route. The photocatalytic activity of CdS/ZnO/RGO nanostructure has been examined for the degradation of methylene blue dye under solar irradiation at room temperature. The CdS/ZnO/RGO nanostructure exhibits five times enhanced photocatalytic activity as compared to CdS nanostructures which is attributed to the formation of heterojunction between the CdS and ZnO and its coupling with the reduced graphene oxide which facilitates the efficient transport of photogenerated charge carriers. Also, CdS/ZnO core/shell nanostructure exhibits very good photostability due to the presence of stable ZnO as cap layer. [ABSTRACT FROM AUTHOR]

Abstract: Thin films of YBa2Cu3O7− δ (YBCO) have been deposited on undecorated and La0.67Sr0.33MnO3 (LSMO) nanoparticles decorated single crystal SrTiO3 (STO) substrate using laser ablation technique and their flux pinning characteristics have been compared using temperature dependent magnetization studies. Significant improvement in the critical current density of YBCO thin film has been observed even at higher applied magnetic field (∼7T). The improved flux pinning properties of YBCO thin films deposited on LSMO decorated STO substrate has been attributed to the presence of ferromagnetic LSMO nanoparticles at the substrate/film interface which seem to be acting as artificially generated magnetic pinning centres leading to improved flux pinning properties. [Copyright &y& Elsevier]

Abstract: ZnO nanostructures synthesized by chemical solution method were observed to exhibit a shape transition from nanoparticle to nanorod when the growth temperature was varied from 130 to 200°C. At the intermediate growth temperatures (150–170°C), nanoparticles start getting attached to form nanorods and exhibit enhanced strain and defects which seems to be due to the presence of interface between attached nanoparticles at these growth temperatures. The difference between valence band maxima and Fermi energy level at intermediate growth temperatures get increases which has been attributed to the enhancement of defects. [Copyright &y& Elsevier]

Abstract: The effect of incorporation of BaTiO3(BTO) nanoparticles on the flux pinning properties of pulsed laser deposited YBCO:BTO thin films was studied. Substantial increase in the critical current density () and the pinning force density () of the nanocomposite thin films was observed. At 77 K, and zero applied magnetic field, the value of for YBCO and YBCO:BTO (2%) thin films were 2.93 MA/cm2 and 6.43 MA/cm2, respectively. At the same temperature and an applied magnetic field of 4 T, the value of increases from 3.6×104 A/cm2 for YBCO thin film to 2.7×105 A/cm2 for YBCO:BTO (2%) nanocomposite thin film. The study of temperature and field dependence of of YBCO and YBCO:BTO thin films indicates similar type of pinning. The lattice mismatch between YBCO and BTO seems to introduce more defects resulting in the improvement of flux pinning properties. [Copyright &y& Elsevier]

Abstract: ZnO and Al-doped ZnO films have been deposited on quartz substrates by ultrasonically assisted chemical vapor deposition technique. Photoluminescence (PL) spectra of the films reveal that Al doping leads to suppression of defect related visible band. Time resolved photoluminescence studies have been carried out for the measurement of lifetime of deep level luminescence. The decay of PL intensity with time has been found to follow biexponential behavior. The relative contributions of fast decay component and slow decay component in total decay process are found to be ∼99% and ∼1% respectively. The values of and are found to decrease with Al doping in ZnO film. The decrease of both and is attributed to increase in non-radiative recombination due to reduction in grain sizes and the decrease in radiative recombination due to suppression of defects. [Copyright &y& Elsevier]

Abstract: Magnetization studies of YBCO:BaZrO3 composite superconductor have been done over a wide range of temperature and applied magnetic field using MPMS SQUID VSM and the results are compared with that of pure YBCO. The analysis of the observed results indicate that there is considerable improvement in the values of critical current density (J C ) and pinning force density (F p ) of YBCO:BaZrO3 composite samples as compared to pure YBCO sample in the entire investigated range of applied magnetic field and temperatures ranging from 4 to 77K. The variation of J C with reduced temperature t (=T/T C ) for the composite samples has been found to be similar to that of pure YBCO sample indicating similar nature of the vortex interaction with pinning centres in both pure and composite samples. The enhancement in the value of J C and F p in the composite samples as compared to pure YBCO sample has been attributed to the increased defect density in the composite samples due to the presence of BZO particles in YBCO matrix. [Copyright &y& Elsevier]

Cobalt ferrite thin film based low loss magnetically tunable bandpass filter in the flip chip configuration is fabricated. Cobalt ferrite thin film was synthesized by ultrasonic assisted chemical vapor deposition technique on the quartz substrate. This was overlaid on a resonator appropriately coupled to 50 Ω feed lines. The initial operating frequency (resonance frequency) of the bandpass filter was 13.8 GHz which was shifted to 12.82 GHz when a small magnetic field (~150 Oe) was applied showing a tunability of ~7%. A large variation in the tunability of the coupled filter is attributed to change in the permeability of the CFO thin film on the application of magnetic field. [ABSTRACT FROM AUTHOR]

Abstract: Films of polyaniline (PANI) and polyaniline–CNTs composites have been synthesized by solution casting technique. Fourier transform infrared spectroscopic studies of PANI and PANI–CNTs composite films indicated the presence of interaction between CNTs and molecular chains of PANI. Dielectric properties of PANI and composite films have been investigated in the frequency range of 8.0–12.0GHz. The real part of permittivity (ε′) and loss factor (tan δ) were found to be higher in PANI–CNTs composite films as compared to the PANI film. The increasing behavior of ε′ and tan δ has been attributed to the interaction present between CNTs and PANI molecular chains and increase of conductivity of PANI films after incorporation of CNTs. [Copyright &y& Elsevier]

Abstract: YBa2Cu3O7−δ–BaTiO3 (4wt.%) (YBCO–BTO (4%)) composite bulk polycrystalline sample has been synthesized by solid state reaction method. The structure of composite sample has been investigated by X-ray diffraction and magnetization measurements were carried out using MPMS SQUID VSM. The superconducting transition temperature of the YBCO–BTO (4%) sample was similar to that of pure YBCO. The critical current density (Jc ) for YBCO–BTO (4%) sample increases significantly as compared to pure YBCO sample. The enhancement of the critical current density in the YBCO–BTO (4%) sample has been attributed to the presence of BaTiO3 nanoparticles acting as artificial pinning centres. The introduction of BaTiO3 particles in YBCO increases pinning force density from 0.71GN/m2 to 1.41GN/m2 at 4K and 0.33MN/m2 to 0.97MN/m2 at 77K. [Copyright &y& Elsevier]

Abstract: Films of polyaniline (PANI) and PANI-nano ZnO composites have been synthesized by solution casting technique. Fourier transform infrared spectroscopic studies of PANI and PANI-nano ZnO composite films indicated the presence of interaction between nano ZnO particles and molecular chains of PANI. Dielectric properties of the PANI and composite films have been investigated in the frequency range of 8.0–12.0GHz. The real part of permittivity (ɛ′) and loss factor (tan δ) were found to decrease in PANI-nano ZnO composite films. The decreasing behavior of ɛ′and tan δ may be attributed to the interaction between nano ZnO particles and PANI molecular chains. The interaction between PANI chains and surface of ZnO nano particles restricts the motion of the dipoles and leads to the decrease of ɛ′and tan δ of the composite films. [Copyright &y& Elsevier]

Abstract: An inorganic/organic hetrojunction has been fabricated by spin coating the p-type polymer poly(3,4 ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) on an n-type zinc oxide (ZnO) film. The ZnO film was deposited by the ultrasonically assisted chemical vapor deposition method on a patterned indium tin oxide (ITO) coated glass substrate. Gold was deposited on top of the PEDOT:PSS film by thermal evaporation. The current–voltage (–) characteristic of ZnO/PEDOT:PSS shows diode-like behavior. The – characteristic was examined in the framework of the thermionic emission model. The ideality factor and barrier height were obtained as 3.8 and 0.63 eV respectively. [Copyright &y& Elsevier]

Abstract: In this paper we report the effect of deposition temperature on the structural and optical properties of ZnO thin films prepared by rf magnetron sputtering. The films grown at lower deposition temperatures were in a state of large compressive stress, whereas the films grown at higher temperature (450°C) were almost stress free. In the absorption spectra, the ZnO excitonic and the Zn surface plasmon resonance (SPR) peaks have been observed. A redshift in the optical band gap of ZnO films has also been observed with the increase in the deposition temperature. The shift in the band gap calculated from the size effect did not match with the observed shift values and the observed shift has been attributed to the compressive stress present in the films. [Copyright &y& Elsevier]

Abstract: Temperature dependent behavior of conduction noise of MgB2 superconductor has been studied. The frequency spectrum of conduction noise shows 1/fα type of behavior, with α =0.7–0.8. Temperature dependence of conduction noise is found to exhibit two peaks at ∼26K and ∼38K respectively. The peak at ∼38K is attributed to movement of vortices and due to fluctuation in resistance from change of state from superconducting to normal state. The peak in the conduction noise at ∼26K is ascribed to the movement of vortices due to enhanced thermally activated vortex hopping. The analysis of enhanced conduction noise in the low temperature region indicates the presence large density of fluctuators with activation energies around 0.048eV. [Copyright &y& Elsevier]

Abstract: ZnO and Co-doped ZnO thin films have been deposited on the sapphire substrate by ultrasonic assisted chemical vapor deposition technique. The films were annealed in vacuum at 450 °C. All the films were highly c-axis orientated and contained no impurity phase. The temperature dependence of the electrical conductivity has been measured in order to identify the dominant conduction mechanism. In the higher temperature region the dominance of thermally activated band conduction was observed whereas in the low temperature region the hopping conduction was found to dominate. The hopping conduction mechanism in the lower temperature range in the film was Mott''s Variable Range Hopping and not the Nearest Neighbor Hopping. The temperature region, where hopping conduction was dominant found to increase by Co doping in ZnO film. The localization length was found to be larger in the Co-doped ZnO film. [Copyright &y& Elsevier]

Abstract: Double layered manganite of La1.4Ca1.6Mn2O7 (DLCMO) was prepared using solid state reaction method and had a metal–insulator transition temperature (T MI) of 125K. The short range 2D-feerromagnetic ordering (TC2) starts growing when T<168K and it gets converted into 3D-ferromagnetic ordering (T C1) at 114K. Low field magnetoresistance (MR) behaviour of the DLCMO was investigated and compared with an infinite layered manganite La0.7Ca0.3MnO3 (LCMO). For DLCMO, in the temperature range between T C1 and T C2, the MR showed a gradual increase with the magnetic field. The observed MR and R–T behaviour of double layered manganite for T C1<T<T C2 has been explained in the frame work of the two phase model [ferromagnetic (FM) domains and paramagnetic (PM) regions] and percolative behaviour of transport in FM–PM mixture. [Copyright &y& Elsevier]

Abstract: Temperature dependence of conduction noise and low field magnetoresistance of layered manganite La1.4Ca1.6Mn2O7 (DLCMO) are reported and compared with the infinite layered manganite La0.7Ca0.3MnO3 (LCMO). The double layered manganite was prepared using standard solid state reaction method and had a metal–insulator transition temperature (TM–I) of 155K. The temperature dependence of susceptibility showed evolution of ferromagnetic ordering at 168K. The observed voltage noise spectral density (SV) shows 1/fα type of behaviour at all temperatures from 77K to 300K. In the ferromagnetic region (T<168K), SV/V2 shows two peaks at 164K and 114K. The observed two peaks in normalised conduction noise of DLCMO is attributed to the excess noise generated due to setting up of short range 2D-ferromagnetic ordering and long range 3D-ferromagnetic ordering at two different temperatures TC2 and TC1. In temperature range between TC1 and TC2, the magnetoresistance (MR) showed a gradual increase with the magnetic field. The observed MR has been explained in the framework of the two phase model [ferromagnetic (FM) domains and paramagnetic (PM) regions]. [Copyright &y& Elsevier]

A single artificial grain boundary in La0.67Ba0.33MnO3 (LBMO) thin film has been prepared by depositing the film on a bicrystal substrate using laser ablation technique. We investigated the magnetic field dependence of magnetoresistance and conductance–voltage characteristics of the grain boundary at 77K. A decrease of nonlinearity of current–voltage characteristics was observed upon application of magnetic field. The results are explained by assuming the presence of two different types of parallel conducting channels (metallic and highly resistive) across the grain boundary. The analysis of the results reveals that the application of magnetic field suppresses magnetic disorders at the grain boundary region and increases metallic conduction channels across the grain boundary. The temperature dependence of the conduction noise of the bicrystal grain boundary was measured at 0 and 1.5kG magnetic field and compared with a microbridge on the LBMO film having no grain boundary. The presence of the grain boundary was found to enhance noise by one order of magnitude. The noise of a bicrystal grain boundary showed a decrease in the presence of 1.5kG magnetic field for T<210K. This decrease of noise confirms that the application of a magnetic field induces more metallic channels across the grain boundary. [Copyright &y& Elsevier]

Studies of rf-SQUID effect in ternary (YRuB2, LuRuB2, LaRu3Si2) and in binary V3Si intermetallic bulk superconductors have been carried out for investigating the nature of grain boundaries in these superconductors. YRuB2 (Tc∼7.5 K), LuRuB2 (Tc∼10 K) and LaRu3Si2 (Tc∼7 K) ternary superconductors are found to show rf-SQUID voltage–flux modulations from 4.2 K to close to Tc. This indicates that the natural grain boundaries in the ternary intermetallic superconductors behave as Josephson weak links. Rf-SQUID effect is not observed in V3Si binary superconductors, which indicates that the grain boundaries in V3Si are not weak link type. STM/STS studies of the YRuB2 and V3Si grain boundaries (GB) are also reported. The interior of the GB in YRuB2 is found to be of quasi-insulating type and thus provides a weak link effect. On the contrary the interior regions of the GB of V3Si is found to be of metallic type and thus provides proximity coupling between the grains of V3Si. [Copyright &y& Elsevier]

La0.67Ca0.33MnO3 (LCMO) and Ag admixed La0.67Ca0.33MnO3 (Ag–LCMO) polycrystalline films have been prepared on SrTiO3 single crystal (100) substrates by ultrasonic spray pyrolysis technique. These films are characterized using XRD, SEM, and temperature dependence of resistivity (ρ-T) and ac susceptibility (χ-T). The films are having cubic structure with lattice parameters as 3.890 and 3.885 A˚ for LCMO and Ag–LCMO films, respectively. The peek in ρ-T curve (Tp) and the ferromagnetic transition temperature (TC) for the Ag-LCMO film is higher than that of LCMO film. The stability of both the films was tested by repeated measurements of its characteristics over a period of one week after several thermal cycling from room temperature to 77 K. In the LCMO film, the peak in the ρ-T curve (Tp) is found to shift towards lower value and conduction noise of the film increases in the subsequent measurements. In the case of Ag–LCMO the value of Tp, TC and conduction noise of the film did not change even after several measurements. Silver segregating at the grain boundaries in Ag–LCMO polycrystalline film seems to be responsible for improving the characteristics of Ag–LCMO films. [Copyright &y& Elsevier]

Significantly enhanced photoelectrochemical (PEC) performance of the visible light active photoanodes of ferroelectric Bi 0.5 Na 0.5 TiO 3 nanostructure has been demonstrated by tuning the electrical polarization of the film. The photocurrent density of unpoled Bi 0.5 Na 0.5 TiO 3 photoanode increases from 0.48 mA cm−2 at 1 V with respect to Ag/AgCl to 1.21 mA cm−2 after negative poling, whereas it decreases to 0.18 mA cm−2 after positive poling. The incident photon-to-current conversion efficiency (IPCE) of the nanostructure photoanodes has been observed to vary from 5% to 28% just by changing the direction of electric polarization. The change in the PEC performance and enhancement in the IPCE value after switching the polarization state of Bi 0.5 Na 0.5 TiO 3 photoanodes have been attributed to the modification in the band bending at the interface of semiconductor electrode/electrolyte, leading to facilitate the increment in photogenerated charge transfer efficiency. The modulation in the band bending and variation in the charge transfer method after switching the polarization state are confirmed by Mott-Schottky (M-S) and electrochemical impedance spectroscopy (EIS) measurements. Our work provides a new visible light active ferroelectric nanostructure material for efficient visible light active photoelectrochemical performance. [Display omitted] • Hydrothermal method has been used to synthesize Bi0.5Na0.5TiO3 nanostructures. • PEC activity of Bi0.5Na0.5TiO3 photoanode improved by changing the polarization state. • Negative poled Bi0.5Na0.5TiO3 photoanode shows current density of 1.21 mAcm-2 at 1 V. • Charge transfer process on the application of electric field polarization is proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Reflux method has been used to synthesize RGO/NaNbO 3 -NRs nanocomposite. • Incorporation of RGO with NaNbO 3 -NRs greatly enhanced photocatalytic and PEC activity. • RGO/NaNbO 3 -NRs photoanode exhibited ∼3-fold enhancement of IPCE than that of NaNbO 3 -NRs. In this present work, reduced graphene oxide (RGO) coupled with hydrothermally grown sodium niobate nanorods (NaNbO 3 -NRs) have been successfully synthesized. The photocatalytic performance of RGO/NaNbO 3 -NRs photocatalyst demonstrated faster photodegradation of organic methylene blue (MB) dye than bare NaNbO 3 -NRs. A ∼6 fold enhancement in the photocatalytic activity of RGO/NaNbO 3 -NRs nanocomposite than that of NaNbO 3 -NRs has been demonstrated towards the degradation of MB dye under similar light illumination. Furthermore, the potentiality of the fabricated NaNbO 3 -NRs and RGO/NaNbO 3 -NRs nanocomposite photoanodes have been investigated for photoelectrochemical (PEC) water splitting. The fabricated RGO/NaNbO 3 -NRs nanocomposite photoanode showed ∼4 times higher photocurrent density than the NaNbO 3 -NRs photoanode. The electrochemical impedance spectroscopy (EIS) and Mott-Schottky (MS) measurements demonstrated that coupling of RGO nanosheets in the RGO/NaNbO 3 -NRs nanocomposite reduced the charge transfer resistance (R ct) at the photoanode/electrolyte interface, increased the donor density (N d), and reduced flat band potential (V fb) of the RGO/NaNbO 3 -NRs, thus significantly improving the PEC performance of the RGO/NaNbO 3 -NRs nanocomposite. The enhancement in the PEC measurements of RGO/NaNbO 3 -NRs nanocomposite is attributed to the extended absorption of the visible portion of the solar spectra and increased mobility of the photogenerated charge transport in the RGO nanosheets, which improve the separation efficiency and reduce the recombination process. The possible charge transfer mechanism has been proposed responsible for the enhanced photocatalytic and PEC water splitting performance. [ABSTRACT FROM AUTHOR]

Metal oxide as a thermoelectric material has shown great attention in recent years due to its outstanding thermal and chemical stability, good oxidation resistance, low cost, etc. This article reports the successful synthesis of tungsten oxide (WO 3) nanoparticles and tungsten oxide-reduced graphene oxide (WO 3 -rGO) nanocomposites and studies of their thermoelectric properties. The structural characteristics of the WO 3 nanoparticles and WO 3 -rGO nanocomposites were examined using XRD and Raman techniques. At 313 K, WO 3 -rGO nanocomposites exhibit an ~ 8.8 times enhancement in the thermoelectric material figure of merit (zT). These excellent performances are further supported by up to ~ 13.7 times enhanced electrical conductivity and a ~ 56% reduction in thermal conductivity compared to WO 3 nanoparticles. It has been concluded that reduce graphene oxide helps in forming a conducting pathway in the WO 3 -rGO nanocomposites, allowing the easy passage of charge carriers in the matrix. [ABSTRACT FROM AUTHOR]

Silver (Ag) nanoparticles decorated NaNbO 3 nanorods (Ag-NaNbO 3) based nanocomposite have been successfully synthesized by simple chemical solution method with the aim to couple the plasmonic and piezo-phototronic effect. The Ag-NaNbO 3 nanocomposite showed much enhanced photocatalytic and photoelectrochemical water splitting properties as compared to bare NaNbO 3. A ∼10 fold enhancement in the photodecomposition of organic MB dye and a ∼9 fold increment in the photocurrent density of photoelectrochemical water splitting was observed as compared to bare NaNbO 3 , which has been attributed to the combined plasmonic and piezo-phototronic effect. The plasmonic effect due to the presence of Ag nanoparticles on the NaNbO 3 surface resulted in enhanced absorption of visible light and piezo-photoelectric effect resulted in better separation of the photogenerated charges due to the built-in electric field. This approach demonstrates a novel strategy for enhancing the performance of silver decorated semiconducting/piezoelectric material for achieving efficient photocatalytic dye degradation and PEC water splitting. Image 1 • Piezoelectric NaNbO 3 and Plasmonic Ag-NaNbO 3 nanocomposites have been synthesized. • Ag-NaNbO 3 exhibited higher photocatalytic and PEC activity as compared to NaNbO 3. • Enhancement is attributed to the coupling of piezo-phototronic and plasmonic effect. • Mechanism of charge transfer process for Ag-NaNbO 3 nanocomposite was proposed. [ABSTRACT FROM AUTHOR]

Developing photoanode with proficient sunlight harvesting, stability as well as enhancing the electron injection across the interface remains a major challenge in the photoelectrochemical water splitting strategy to generate hydrogen. Herein, we design and fabricate an organic/inorganic TiO 2 /C 3 N 4 /CNT photoanode by a hydrothermal technique which exhibits much enhanced photoelectrochemical properties. The TiO 2 /C 3 N 4 /CNT photoanode exhibits a photocurrent density of 2.94 mA/cm2, which is ~6.4 time higher than pristine graphitic carbon nitride (C 3 N 4) at an applied bias potential of 0.6 V vs. Ag/AgCl. The excellent photoelectrochemical performance benefits from the impactful migration of photo-induced electrons at the TiO 2 /C 3 N 4 interface from C 3 N 4 to TiO 2 and their intimate interface contact with CNT. Kelvin probe force microscopy result shows a smaller interface barrier height (~10 meV) between TiO 2 and C 3 N 4 , suggesting that electrons transport is favored through TiO 2 /C 3 N 4 interfaces in a ternary photoanode. The TiO 2 /C 3 N 4 /CNT photoanode exhibited an onset potential of 0.25 V vs. Ag/AgCl which is much lower compared to pristine C 3 N 4. The electrochemical impedance spectroscopy results also confirmed the enhanced electron injection across the interface in a ternary photoanode. These results demonstrate a promising approach to develop a highly proficient and visible light active photoanode with excellent stability for renewable energy applications. Image 1 • An Organic/Inorganic ternary photoanode was synthesized by the hydrothermal method. • KPFM results shows that electron transport is favored through TiO 2 /C 3 N 4 interfaces. • The ternary photoanode exhibits ~6.4 time higher photocurrent density than C 3 N 4. • The ternary photoanode exhibited excellent photostability. [ABSTRACT FROM AUTHOR]

In this work, we have successfully synthesized silver nanoparticles (Ag-NPs) decorated binary PaNi/NBO nanocomposite by facile chemisorption route and demonstrated enhanced photoelectrochemical (PEC) water splitting activity. The ternary Ag/PaNi/NBO nanocomposite photoanode exhibits ∼5 fold higher current density than pristine NaNbO 3 nanofibers (NBO-NFs). The ternary Ag/PaNi/NBO photoanode exhibits a current density of 5.93 mA/cm2 at 0.9 V with respect to Ag/AgCl, whereas the pristine NBO-NFs photoanode exhibits only 0.85 mA/cm2 at 0.9 V. The improved performance is correlated to the high surface area, formation of the type-II heterojunction among PaNi and NBO-NFs and the introduction of the plasmonic behaviour of Ag-NPs as it expands the absorption of the visible part of the solar spectrum, which together decreases the recombination of charges with strong redox capability. Furthermore, the ternary Ag/PaNi/NBO photoanode showed lower charge transfer resistance (R ct) in the EIS measurements and improved incident photon to current efficiency (IPCE) of ∼31.3% which is ∼23% higher to the IPCE of bare NBO-NFs photoanode. Thus, these results suggest that the ternary Ag/PaNi/NBO nanocomposite is a promising material for PEC activity and wide practical applications. Image 1 • Ternary Ag/PaNi/NBO nanocomposites was synthesized by chemical solution route. • Ag/PaNi/NBO photoanode exhibited ∼5 fold higher photocurrent density than NBO. • The enhancement is attributed to the type-II heterojunction and plasmonic effect of Ag. • Possible charge transfer and separation mechanism of Ag/PaNi/NBO was proposed. [ABSTRACT FROM AUTHOR]

Highlights • Visible active CZTS alerted CdS/TiO 2 tandem photoanode made-up by low cost technique. • CZTS/CdS/TiO 2 /FTO shows higher current density due to strong visible light absorption. • PEC properties of photoelectrode have significantly improved by surface modification. • Efficient separation of charge carriers after deposition of CdS and CZTS on TiO 2 /FTO. Abstract A tandem photoanode consisting of Cu 2 ZnSnS 4 (CZTS) nanoparticles layer over CdS/TiO 2 heterostructure thin film on FTO substrate has been fabricated for photoelectrochemical hydrogen generation. CdS thin film has been deposited by chemical bath deposition over the spin-coated TiO 2 thin film, which is followed by the deposition of CZTS nanoparticles layer by spray coating technique resulting in a CZTS/CdS/TiO 2 /FTO photoanode. The coating of CZTS nanoparticles layer over CdS/TiO 2 films resulted in the tandem structure of different band level positions, which enhances the optical absorption in the visible region and also leads to higher separation of the photogenerated charge carriers. A substantial enhancement (39 times) in the PEC activity has been demonstrated for the CZTS/CdS/TiO 2 /FTO photoanode as compared to TiO 2 /FTO photoanode, which is due to cascade band gap from 3.2 eV to 1.7 eV and formation of heterojunction at interfaces. The enhancement in the charge transport properties of CZTS/CdS/TiO 2 /FTO photoanode has been confirmed from the electrochemical impedance spectroscopy (EIS) measurement. The EIS results confirm that the CZTS/CdS/TiO 2 /FTO photoanode exhibited lowest charge transfer resistance (R ct = 302 Ω/cm2) as compared to CdS/TiO 2 (R ct = 615 Ω/cm2) and TiO 2 (R ct = 1700 Ω/cm2) photoanode. A mechanism depicting the enhanced the performance of photoelectrochemical (PEC) CZTS/CdS/TiO 2 /FTO photoanode has been proposed. [ABSTRACT FROM AUTHOR]

Abstract In the present work, nanostructures comprising of plasmonic silver (Ag) nanoparticles (NPs) decorated on the hydrothermally grown bismuth sulfide nanorods (Bi 2 S 3 –NR) and hierarchical nanoflowers (Bi 2 S 3 NF) have been successfully synthesized by chemical route. We have fabricated the nanostructured photoanodes and demonstrated their enhanced photoelectrochemical (PEC) performance for water splitting applications. Bismuth sulfide nanoflowers have shown appreciable increased PEC activity due to its hierarchical structure as compared to the nanorods facilitated by the faster charge transport due to the availability of more interfacial sites. Among all, Ag/Bi 2 S 3 NF photoanode has exhibited highest photocurrent density (12.34 mA/cm2 at 2 V vs. Ag/AgCl) which is ∼2 fold higher as compared to Bi 2 S 3 nanoflowers. A ∼3 fold enhancement in the incident photon-to-current conversion efficiency is achieved by Ag/Bi 2 S 3 NF photoanode as compared to Bi 2 S 3 NF photoanode. The remarkable enhancement in the photocurrent density of Bi 2 S 3 after grafting metal plasmons is attributed to its enhanced photoresponse, faster transfer of plasmon mediated hot electrons from excited state of Ag NPs to Bi 2 S 3 surface and higher separation efficiency of photogenerated charge carriers facilitated by the metal-semiconductor interface. A plausible mechanism is also proposed for the improved PEC water splitting over Ag/Bi 2 S 3 NF photoanode. Graphical abstract Plasmonic silver (Ag) NPs have been successfully grafted on the hydrothermally grown bismuth sulfide nanorods (Bi 2 S 3 –NR) and hierarchical nanoflowers (Bi 2 S 3 NF) via chemical method. The Ag NPs coupled Bi 2 S 3 photoanode (Ag/Bi 2 S 3 NF) has demonstrated ∼2 and ∼3 fold enhancement in the photocurrent density and incident photon-to-current conversion efficiency (IPCE), respectively as compared to Bi 2 S 3 NF photoanode. The observed enhancement in the PEC activity for Ag/Bi 2 S 3 NF photoanode is attributed to the faster transport of plasmon mediated hot electrons from excited state of Ag NPs to the conduction band of Bi 2 S 3 nanoflowers and the slower recombination rate of photogenerated charge carriers facilitated by the metal-semiconductor interface. Image 1 Highlights • Bi 2 S 3 has been synthesized in the form of nanorods and hierarchical nanoflowers by hydrothermal method. • Plasmonic Ag NPs have been grafted on the Bi 2 S 3 nanostructures by chemical route. • A ∼2 and ∼3 fold enhancement in the photocurrent density and IPCE is achieved by Ag/Bi 2 S 3 NF as compared to Bi 2 S 3 photoanode. • The improvement is due to the enhanced photoresponse and surface plasmonic effect. [ABSTRACT FROM AUTHOR]

Single-phase Cu 2 ZnSnS 4 (CZTS) thin films have been spray deposited on glass substrate, using uniform size oleic acid coated CZTS nanoparticles and the effect of heating temperature (75 °C to 300 °C) on the structural and optical properties have been investigated. X-ray diffraction results confirmed the formation of the single phase CZTS with a preferred orientation in (112) plane. The crystallite sizes of these films are ~7.0 ± 0.5 nm but the intrinsic strain present in the nanostructured films decreases from 9.1 × 10 −3 to 1.3 × 10 −3 with the increase of the heating temperature from room temperature to 300 °C. Optical band gap of the as deposited CZTS films is ~1.72 eV and it decreases to 1.45 eV for the CZTS films heated at 300 °C. The observed red shift in the band gap of CZTS films with the heating temperature has been attributed to a reduction in the intrinsic strain present in the film with the increase in the heating temperature. [ABSTRACT FROM AUTHOR]

Superhydrophobic transparent thin films using Mn doped zinc oxide (Mn/ZnO) and polystyrene (PS) composites have been synthesized successfully by chemical solution method. The nanocomposites thin films were fabricated by using Mn/ZnO and PS mixture in toluene, followed by film casting on glass substrate. For a comparison ZnO nanoparticles thin film was also prepared with PS. Mn/ZnO nanostructures have been synthesized by hydrothermal method using hexamethylenetetramine (HMTA) as a capping agent. The XRD analysis shown that the development of hexagonal wurtzite structure of Mn/ZnO with preferred (101) orientation. SEM analysis shown that Mn/ZnO nanorods have been uniformly dispersed in the PS matrix. Water contact angle (WCA) was found as 107° and 151° for the ZnO@PS and Mn doped ZnO@PS thin film, respectively. The transparency of the Mn doped ZnO@PS films are also large (∼90%) as compared to ZnO@PS film (∼80%) which is attributed to enhanced energy band gap of ZnO after Mn doping. The larger contact angle (WCA ∼151°) in the Mn/ZnO@PS thin film has been recognized to the rough surface of PS thin film due to the presence of Mn/ZnO nanorods. The present process is very simple and embrace ability for extensive applications for making super hydrophobic transparent surfaces. [ABSTRACT FROM AUTHOR]

In the present work, photoanodes comprising of NaNbO 3 nanorods and Ag nanoparticles decorated NaNbO 3 nanorods have been fabricated by using hydrothermal and chemical solution method respectively. Photoelectrochemical water splitting performance of the fabricated photoanodes have been measured and it is found that Ag decorated NaNbO 3 nanorods exhibit ∼4 fold enhancement in photocurrent as compared to bare NaNbO 3 nanorods. The enhancement in the photoelectrochemical water splitting activity of Ag decorated NaNbO 3 nanorods is attributed to efficient charge carrier separation and visible light sensitization due to Ag nanoparticles on NaNbO 3 nanorods. [ABSTRACT FROM AUTHOR]

The resistive switching behavior and nonvolatile memory effects have been investigated in poly (3-hexylthiophene) (P3HT) and carbon nanotubes (CNT) composite thin films. The memory devices with FTO/P3HT-CNT/Al structure were fabricated by varying the CNT content in the composite. The memory device with 4% CNT in P3HT exhibited a typical bipolar resistive switching with set voltage of ∼1.8 V and a high ON/OFF ratio of >10 2 . The nonvolatile behavior of the device has been studied by the retention test and showed good retention properties for >10 3  s. The resistance-temperature dependence of different resistance states has also been investigated. Ohmic conduction was found to be a dominant conduction mechanism in low bias region, whereas for the high voltage regime space charge limited conduction was found to be the ruling current conduction mechanism. Bipolar resistive switching characteristic of the nanocomposite film is explained on the basis of rupture and formation of carbon-rich filaments. [ABSTRACT FROM AUTHOR]

Thermoelectric studies of Cu 2 ZnSnS 4 (CZTS) thin films deposited at different substrate temperatures by ultrasonic assisted chemical vapor deposition technique have been carried out. In order to identify the effect of compactness, crystallinity and formation of secondary phases (Cu 2 − x S and SnS 2 ) on the thermoelectric properties of CZTS thin films, the films were deposited at different substrate temperatures. Detailed analysis of temperature dependent electrical resistivity (ρ) and Seebeck coefficient (S) have been carried out. Significant enhancement in the value of thermoelectric power factor (S 2 /ρ) is achieved in CZTS film deposited at 375 °C substrate temperature, which is correlated to the compactness of thin films, improved crystallinity and presence of metallic secondary phase. Furthermore, Surface topography and surface potential studies also carried out to study the roughness and distribution of interfaces between CZTS and secondary phases (Cu 2 − x S and SnS 2 ) in CZTS thin films. [ABSTRACT FROM AUTHOR]

Bi 2 Te 3 –MWCNT nanocomposite has been synthesized by hydrothermal technique and demonstrate the role of MWCNT for thermoelectric properties. Herein, MWCNT has been used as conducting filler, which leads to the enhancement in the electrical conductivity in the case of nanocomposite. Bi 2 Te 3 –MWCNT nanocomposite shows ~22% decrease in the thermal conductivity as compared to Bi 2 Te 3 nanostructures, which is attributed to the enhanced phonon scattering at the interfaces of Bi 2 Te 3 –MWCNT nanocomposite. Due to the increase in the electrical conductivity and decrease in the thermal conductivity, the overall enhancement in the figure of merit is ~45% in Bi 2 Te 3 –MWCNT nanocomposite as compared to Bi 2 Te 3 nanostructures. [ABSTRACT FROM AUTHOR]

A noble metal-free photocatalyst, consisting of graphitic carbon nitride (g-C 3 N 4 ), TiO 2 and carbon nanotubes (CNT) was synthesized by a facile hydrothermal method and its application for the photocatalytic decolouration of methylene blue (MB) dye under visible light irradiation has been demonstrated. The microstructure, morphology, structural and optical properties of the synthesized nanocomposites was systematically studied using TEM, SEM, XRD, RAMAN, FTIR and UV–Vis DRS techniques. The g-C 3 N 4 /TiO 2 /CNT ternary nanocomposite exhibits five times higher photocatalytic activity compared to bare g-C 3 N 4 under visible light irradiation. Enhanced photocatalytic performance of the ternary nanocomposite has been attributed to the synergistic effects of three components: Multistep charge transfer between heterojunction formation at g-C 3 N 4 /TiO 2 interface and CNT, enhanced visible-light absorption and effective charge separation. A possible reaction mechanism has been proposed and scavenger experiment has been carried out to find the role of active radical species responsible for the dye decolouration. Additionally, the g-C 3 N 4 /TiO 2 /CNT photocatalyst retained excellent stability even after several cycles. This study offers a promising way of developing a highly efficient, noble metal-free, stable and visible-light-driven photocatalyst to promote the utilization of solar energy for environmental purification. [ABSTRACT FROM AUTHOR]

Flexible PVDF/NaNbO 3 /RGO thin films have been synthesized and its application in nanogenerator has been explored. In order to understand the effect of the addition of nanofillers NaNbO 3 and RGO in PVDF, we have also synthesized and studied PVDF/RGO and PVDF/NaNbO 3 nanocomposite films. Even though the β-phase contents are nearly same in the three nanocomposite films, it has been found that the output voltage generated from PVDF/NaNbO 3 /RGO nanocomposite film based nanogenerator is maximum (∼2.16 V) with a short circuit current of 0.383 μA. It has been concluded that NaNbO 3 nanorods help in the alignment of the electric dipoles in PVDF and also due to the inherent piezoelectric property, it contributes in the overall piezoelectric property of the film. On the other hand presence of RGO helps to move the charges generated inside the film and further allow the dipoles of PVDF to align which leads to enhanced piezoresponse. [ABSTRACT FROM AUTHOR]

[Display omitted] • Self-biased TE-coupled PEC hybrid system for hydrogen generation is demonstrated. • The Ag/NaNbO 3 photoanode onset potential is cathodic shifted in a hybrid system. • A ∼17 times enhancement in the H 2 production of TE-coupled PEC system is achieved. Nanostructure semiconductor photoactive materials are often used as working photoelectrodes to absorb solar light in conventional photoelectrochemical (PEC) cells for water splitting to demonstrate enhanced PEC performance. However, an external bias is required to start PEC water splitting reactions for the generation of hydrogen. Here, we demonstrate a novel way of designing a self-biased hybrid system that combines a darkened thermoelectric device (TE) and a photoelectrochemical cell with a visible light-active n-type Ag/NaNbO 3 photoanode to produce hydrogen via water splitting by utilizing the entire solar spectrum. This method can combine utilization of a visible light photon energy from the Ag/NaNbO 3 photoanode with thermal energy from the darkened TE device to overcome the overpotential requirements. Upon light illumination, the photoactive behaviour of the Ag/NaNbO 3 photoanode and the voltage generated from the darkened TE device in our hybrid system modifies the band positions of an Ag/NaNbO 3 photoanode and spontaneously provide the external overpotential requirement for the PEC process and enhances the H 2 production. Compared to the stand-alone PEC device, the TE-coupled PEC hybrid system exhibited ∼17 times enhancement in the photocurrent density and H 2 production at zero bias. The electrochemical impedance spectroscopy analysis also shows that the charge transfer process gets significantly enhanced in the hybrid PEC system compared to the PEC cell alone. This finding indicates the synergistic coupling between TE and PEC cells, where a single light energy source can increase H 2 production in the hybrid systems without needing an external bias. [ABSTRACT FROM AUTHOR]

A Semiconductor to metal transition has been observed in hydrothermally synthesized CoFe 2 O 4 (CFO) nanoparticles. Temperature dependent Seebeck coefficient was measured in order to confirm the type of majority charge carriers and conductivity vs. temperature measurement was performed to get the activation energy. The CFO nanoparticles shows p-type semiconducting behaviour at lower temperature as confirmed by the sign of Seebeck coefficient and at elevated temperatures a sign inversion in Seebeck voltage was observed. The p-type and n-type semiconducting behaviour have been attributed to hopping of holes and electrons between Co 3+ –Co 2+ and Fe 2+ –Fe 3+ respectively dominating at different temperatures. [ABSTRACT FROM AUTHOR]

Polyaniline (PANI) coupled Zinc oxide (ZnO) nanocomposite has been synthesized by the chemisorption method and demonstrated its potential applications for photocatalytic degradation of methylene blue dye and photoelectrochemical (PEC) water splitting. A ∼7 fold enhancement in the photodegradation activity and ∼3 fold enhancement in the incident photon-to-electron conversion efficiency is observed for PANI/ZnO nanocomposite as compared to bare ZnO nanorods. The observed enhancement in the photocatalytic and photoelectrochemical activity is attributed to the photosensitization effect of visible light responsive PANI and the formation of type-II heterojunction between ZnO and PANI leading to the efficient separation and faster transfer of photoinduced charge carriers at the interface. A possible mechanism for the enhanced photocatalytic activity and photoelectrochemical water splitting for PANI/ZnO nanocomposite has been proposed. [ABSTRACT FROM AUTHOR]

In our work, zinc indium sulfide coupled polyaniline (ZnIn 2 S 4 /PANI) nanocomposites were synthesized using chemisorption method. The substantial enhancement in the photocatalytic and photoelectrochemical (PEC) water splitting activity under visible light illumination was demonstrated. ZnIn 2 S 4 /PANI nanocomposites were shown ∼3 times improvement in the photodegradation of methylene blue (MB) dye as compared to bare ZnIn 2 S 4 (ZIS) nanoflakes. In addition, the ZIS/PANI nanocomposite photoelectrode was exhibited ∼3 times enhancement in photocurrent density (∼260 μA/cm2 at 0.8 V vs. Ag/AgCl) as compared to ZnIn 2 S 4 photoelectrode. However, the ZIS/PANI photoanode was demonstrated ∼5 fold enhancement in the incident photon to current conversion efficiency (IPCE) than bare ZIS. The enhancement in the photodegradation and PEC water splitting activity of ZIS/PANI nanocomposite is ascribed to extended visible light absorption, and synergetic effect of PANI along with type-II heterojunction formation, which is beneficial for separation of charge and faster transfer efficiency of photogenerated charge carriers. This study demonstrates that establishing a heterostructure system by coupling a ternary chalcogenide semiconductor with a conducting polymer is effective for photocatalytic wastewater treatment and PEC water splitting applications. • ZnIn 2 S 4 nanoflakes were synthesized by hydrothermal method. • ZnIn 2 S 4 /PANI nanocomposites were synthesized by a simple chemisorption method. • ZnIn 2 S 4 /PANI nanocomposites shows enhanced photocatalytic activity and PEC performance. • The stability and reusability of ZnIn 2 S 4 /PANI nanocomposites were confirmed. [ABSTRACT FROM AUTHOR]

Abstract: In the present work, we report fabrication and current–voltage characteristics of ZnO/α-NPD:F4-TCNQ based inorganic–organic hybrid junction. Current–voltage characteristics of hybrid junctions show diode like behavior. The effect of organic layer doping on the diode like characteristics of the junction has been investigated. The diode parameters viz. barrier height, ideality factor and rectification ratio have been calculated from the current–voltage semi-log plots. The improvement of diode parameters i.e. increase in rectification ratio and decrease in barrier height as well as improvement in ideality factor has been observed with doping. The improvement of the diode parameters has been attributed to the modification at ZnO/α-NPD interface. The current is also found to increase with the increase in doping concentration which has been attributed to the increased conductivity of α-NPD and interface barrier lowering after doping of α-NPD with F4-TCNQ. [ABSTRACT FROM AUTHOR]

Two sets of single domain CoFe 2 O 4 (CFO) nanoparticles have been synthesized using hydrothermal technique which are of the same sizes, but with different amount of strain/defects. The nanoparticles synthesized at a lower growth temperature (80 °C) exhibit high density of planar defects and oxygen vacancies as compared to the CFO nanoparticles grown at higher temperature (180 °C). The CFO nanoparticles with high density of defects also possess higher intrinsic strain. The nanoparticles with higher strain/defects exhibit higher coercivity and smaller value of saturation magnetization. The effect of strain on the magnetization characteristics of CFO nanoparticles is simulated using the Object Oriented MicroMagnetic Framework. The observed larger value of coercivity for the CFO nanoparticles with higher intrinsic strain is attributed to strain induced enhanced anisotropy of the nanoparticles. [ABSTRACT FROM AUTHOR]