Sadia Ameen

Highly sensitive hydrazine chemical sensor fabricated by modified electrode of vertically aligned zinc oxide nanorods.

A highly sensitive, reliable and reproducible hydrazine chemical sensor was fabricated using vertically aligned ZnO nanorods (NRs) electrode. The low temperature hydrothermal process was adopted to synthesize the vertically aligned ZnO NRs on fluorine doped tin oxide (FTO) glass. The morphological characterizations revealed the vertical arrangement of highly dense ZnO NRs on FTO substrates. The ultraviolet diffused reflectance spectroscopy (UV-DRS) of aligned ZnO NRs electrode obtained the band gap of ~3.29eV which was close to that of bulk ZnO nanomaterials. The synthesized aligned ZnO NRs electrode was directly used to elucidate the chemical sensing performance towards the detection of hydrazine by simple current-voltage (I-V) characteristics. The aligned ZnO NRs electrode based hydrazine chemical sensor presented a significantly high sensitivity of ~4.42446×10(-5) A mM(-1) cm(-2) and the detection limit of ~515.7 μM with a correlation coefficient (R) of ~0.73297 and a short response time (10s). The electrochemical analysis of vertically aligned ZnO NRs electrode in the presence of hydrazine showed the increased current with high height of anodic peak which confirmed the involvement of high electron transfer process via high electrocatalytic activity of the electrode.

Vertically Aligned ZnO Nanorods on Hot Filament Chemical Vapor Deposition Grown Graphene Oxide Thin Film Substrate: Solar Energy Conversion

Vertically aligned zinc oxide (ZnO) nanorods (NRs) were grown by the low-temperature hydrothermal method on graphene oxide (GO) coated FTO substrates, where GO was directly deposited on fluorine doped tin oxide (FTO) substrates using hydrogen (H(2), 65 sccm) and methane (CH(4), 50 sccm) through hot filament chemical vapor deposition (HFCVD) technique. The vertically aligned ZnO NRs were applied as effective photoanode for the fabrication of efficient dye sensitized solar cells (DSSCs). Highly uniform ZnO NRs were grown on GO deposited FTO substrate with the average length of ∼2-4 μm and diameter of ∼200-300 nm. The possible mechanism of grown ZnO NRs clearly revealed the significant role of GO on FTO in architecting the aligned growth of ZnO NRs. The grown vertically aligned ZnO NRs possessed a typical wurtzite hexagonal crystal structure. The structural and the optical studies confirmed the formation of partial hydrogen bonding between surface functional groups of GO and ZnO NRs. A solar-to-electricity conversion efficiency of ∼2.5% was achieved by DSSC fabricated with ZnO NRs deposited on graphene oxide (GO-ZnO NRs) thin film photoanode. The presence of GO on FTO substrate expressively increased the surface area of GO-ZnO photoanode, which resulted in high dye loading as well as high light harvesting efficiency and thus ensued the increased photocurrent density and the improved performance of DSSCs.

Photocurrent Induced by Conducting Channels of Hole Transporting Layer to Adjacent Photoactive Perovskite Sensitized TiO2 Thin Film: Solar Cell Paradigm

A high performance perovskite solar cell was fabricated using the distinguished morphology of polyaniline nanoparticles (PANI-NPs) as an efficient hole transporting layer (HTL) with methylammonium lead iodide perovskite (CH3NH3PbI3) as sensitizer. PANI-NPs were simply synthesized by the oxidative chemical polymerization of aniline monomer at 0-5 °C. A reasonable solar-to-electricity conversion efficiency of ∼6.29% with a high short circuit current (JSC) of ∼17.97 mA/cm(2) and open circuit voltage (VOC) of ∼0.877 V were accomplished by Ag/PANI-NPs/CH3NH3PbI3/mp-anatase-TiO2/bl-TiO2/FTO perovskite solar cell. The transient photocurrent and photovoltage studies revealed that the fabricated solar cell showed better charge transport time, diffusion coefficient, diffusion length, and charge collection efficiency. Herein, the use of PANI-NPs as the HTL improved the charge carrier generation and the charge collection efficiency of the fabricated solar cell.

Iodine doped polyaniline thin film for heterostructure devices via PECVD technique: Morphological, structural, and electrical properties

AbstractThe deposition of undoped and iodine (I2)-doped polyaniline (PANI) on TiO2 thin film was carried out using plasma-enhanced chemical vapor deposition (PECVD) under different power inputs for the fabrication of p-polyaniline/n-TiO2 heterostructure devices. The increment in the size of TiO2 nanoparticles was observed after I2 doping by PECVD. The crystalline properties were altered upon I2 doping, suggesting a subtractive interaction between PANI and I2 moieties during PECVD. The significant changes in the structural and optical properties confirmed the I2 doping of PANI with strong bonding to the TiO2 nanomaterials. The existence of hydrogen bonding between the imine (-NH) of PANI and the hydroxyl (-OH) group of TiO2 nanomaterials was investigated by X-ray photoelectron spectroscopy characterization. A device fabricated by PANI/TiO2 or I2-PANI/TiO2 thin film with a top platinum (Pt) layer exhibited nonlinear behavior of current (I)-voltage (V) curve, i.e., moderate diode behavior. Compared to the Pt/PANI/TiO2 heterostructure device, the Pt/I2-PANI/TiO2 heterostructure device showed improved I–V properties with a considerably higher current of 0.050 mA, which might be attributed to the I2 doping-induced generation of large numbers of polarons in the PANI bandgap.

Structural, morphological and sensing properties of layered polyaniline nanosheets towards hazardous phenol chemical

Reliable sensing properties towards hazardous phenol chemical were detected by the novel working electrode of layered polyaniline (PANI) nanosheets. The layered PANI nanosheets were synthesized by the chemical polymerization of aniline monomer in the presence of hydrochloric acid and ammonium persulphate at 5 °C. The morphological, structural, optical, electrical and electrochemical properties of layered PANI nanosheets were extensively studied. The electrochemical behavior of layered PANI nanosheets based electrode was demonstrated by the electrochemical impedance spectroscopy (EIS) and cyclovoltametry (CV) measurements. The layered PANI nanosheets electrode showed reasonably good electrocatalytic activity towards the detection of phenol chemical, which resulted from the high redox current and low RCT. The current-voltage (I-V) characteristics were used to elucidate the sensing parameters of the fabricated phenol chemical sensor with layered PANI nanosheets electrode. The fabricated phenol chemical sensor with layered PANI nanosheets electrode significantly attained the high sensitivity of ~1485.3 μA mM(-1)cm(-2) and the detection limit of ~4.43 μM with correlation coefficient (R) of ~0.9981 and short response time (10 s).

A sea-cucumber-like hollow polyaniline spheres electrode-based chemical sensor for the efficient detection of aliphatic alcohols

Sea-cucumber-like hollow polyaniline (PANI) spheres were synthesized by the chemical polymerization of aniline monomers in the presence of salicyclic acid. The synthesized sea-cucumber-like hollow PANI spheres were applied as a working electrode for the fabrication of highly sensitive, reliable and reproducible chemical sensors for detecting ethanol and other alcohols. The sea-cucumber-like hollow PANI spheres were extensively characterized in terms of their morphological, structural, optical, electrical and electrochemical properties. The morphological characterization revealed a sea-cucumber-like hollow morphology with a uniform decoration of nanofibrils covering the shell of the spheres. Cyclic voltammetry and electrochemical impedance spectroscopy (EIS) measurements were performed to elucidate the electrochemical behavior of sea-cucumber-like hollow PANI spheres electrode towards the detection of aliphatic alcohols. The sensing performances of the synthesized sea-cucumber-like hollow PANI spheres electrode towards the detection of alcohols were analyzed by the current (I)–voltage (V) characteristics. The sea-cucumber-like hollow PANI spheres electrode based ethanol chemical sensor showed considerably high sensitivity of ∼426.5 μA mM−1 cm−2 and a detection limit of ∼515.7 μM with a correlation coefficient (R) of ∼0.90157 and a short response time (10 s).

Controlled synthesis and photoelectrochemical properties of highly ordered TiO2 nanorods

Highly ordered TiO2 nanorods (NRs) were grown directly on fluorine doped tin oxide (FTO) substrate by a single step hydrothermal synthesis at 150 °C. The morphology of TiO2 was significantly altered by changing the solvents of ethanol/deionized (DI) water as the precursor solutions. With ethanol/DI water (80 : 20 v/v) as solvent, the highly ordered tetragonal TiO2 NRs were achieved on FTO substrates with the average lengths of ∼2–4 μm and diameters ∼50–70 nm respectively. While, the round headed and distorted hexagonal TiO2 NRs were formed with ethanol/DI water ratios of 50 : 50 v/v and 0 : 100 v/v as the precursor solutions respectively. The grown TiO2 NRs possessed the anatase phase with typical tetragonal crystal structures. XPS studies evidenced that the grown TiO2 NRs exhibited the O : Ti stoichiometric ratio of 2 : 1 with lower impurities of the carbon species. The grown TiO2 NRs thin film substrates were applied as photoanodes for efficient dye-sensitized solar cells (DSSCs). A solar-to-electricity conversion efficiency of ∼3.2% was achieved by DSSC, fabricated with highly ordered tetragonal TiO2 NRs photoanode, whereas DSSC with the distorted hexagonal TiO2 NRs photoanode showed inferior overall conversion efficiency (∼1.08%). The improved photovoltaic performance was credited to the highly ordered morphology of the TiO2 NRs, which executed the high charge collection and the transfer of electrons at the interfaces of the TiO2 NRs photoanode and the electrolyte layer.

Effective D-A-D type chromophore of fumaronitrile-core and terminal alkylated bithiophene for solution-processed small molecule organic solar cells

A new and novel organic π-conjugated chromophore (named as RCNR) based on fumaronitrile-core acceptor and terminal alkylated bithiophene was designed, synthesized and utilized as an electron-donor material for the solution-processed fabrication of bulk-heterojunction (BHJ) small molecule organic solar cells (SMOSCs). The synthesized organic chromophore exhibited a broad absorption peak near green region and strong emission peak due to the presence of strong electron-withdrawing nature of two nitrile (–CN) groups of fumaronitrile acceptor. The highest occupied molecular orbital (HOMO) energy level of –5.82 eV and the lowest unoccupied molecular orbital (LUMO) energy level of –3.54 eV were estimated for RCNR due to the strong electron-accepting tendency of –CN groups. The fabricated SMOSC devices with RCNR:PC60BM (1:3, w/w) active layer exhibited the reasonable power conversion efficiency (PCE) of ~2.69% with high short-circuit current density (JSC) of ~9.68 mA/cm2 and open circuit voltage (VOC) of ~0.79 V.

Furan-bridged thiazolo [5,4-d]thiazole based D–π–A–π–D type linear chromophore for solution-processed bulk-heterojunction organic solar cells

Novel furan-bridged thiazolo[5,4-d]thiazole based π-conjugated organic chromophore (RFTzR) was formulated and utilized for small molecule organic solar cells (SMOSCs). The presence of furan spacer along with two terminal alkyl units significantly improved its absorption and solubility in the common organic solvents. RFTzR exhibited the reasonable HOMO and LUMO energy levels of −5.36 eV and −3.14 eV, respectively. The fabricated SMOSCs with RFTzR (donor) and PC60BM (acceptor) as photoactive materials presented relatively high power conversion efficiency of ∼2.72% (RFTzR : PC60BM, 2 : 1, w/w) along with good open-circuit voltage of ∼0.756 V and high photocurrent density of ∼10.13 mA cm−2, which might attribute to its improved absorption, electrochemical properties and the presence of strong electron-withdrawing furan moieties.

Azadirachta indica plant-assisted green synthesis of Mn3O4 nanoparticles: Excellent thermal catalytic performance and chemical sensing behavior.

The leaf extract of Azadirachta indica (Neem) plant was utilized as reducing agent for the green synthesis of Mn3O4 nanoparticles (NPs). The crystalline analysis demonstrated the typical tetragonal hausmannite crystal structure of Mn3O4, which confirmed the formation of Mn3O4 NPs without the existence of other oxides. Green synthesized Mn3O4 NPs were applied for the catalytic thermal decomposition of ammonium perchlorate (AP) and as working electrode for fabricating the chemical sensor. The excellent catalytic effect for the thermal decomposition of AP was observed by decreasing the decomposition temperature by 175 °C with single decomposing step. The fabricated chemical sensor based on green synthesized Mn3O4 NPs displayed high, reliable and reproducible sensitivity of ∼569.2 μA mM(-1) cm(-2) with reasonable limit of detection (LOD) of ∼22.1 μM and the response time of ∼10 s toward the detection of 2-butanone chemical. A relatively good linearity in the ranging from ∼20 to 160 μM was detected for Mn3O4 NPs electrode based 2-butanone chemical sensor.