1D Nanorods Research Articles

Robust superhydrophobic 1D Ni3S2 nanorods coating for self-cleaning and anti-scaling

Enormous attention has been attracted by Ni3S2 with various microstructures and excellent properties. In this work, a solvothermal reaction was adopted to fabricate 1D Ni3S2 nanorods coating. Then a superhydrophobic surface was achieved by the followed myristic acid modification. This superhydrophobic coating significantly hindered the infiltration of water. The attached contaminants could be easily carried away by water droplets owing to the low adhesion of the coating surface. In addition, the cooperation of low surface energy and 1D nanorods structure exhibited prominent anti-scaling property that effectively blocked the deposition of calcium carbonate. Moreover, it was confirmed that this superhydrophobic coating displayed outstanding thermostability, UV resistance and durability. In addition, water sand scouring and ultrasonic vibration tests were conducted to examine the mechanical stability, and the tested samples still maintained their superhydrophobicity and integrated nanorods structure. These excellent properties make the Ni3S2 superhydrophobic coating a promising barrier for anti-scaling.

Defective synergy of 2D graphitic carbon nanosheets promotes lithium-ion capacitors performance

2D carbon materials show extraordinarily promising prospects in energy storage systems. To improve the performance of lithium-ion capacitors (LICs), it is urgently necessary for addressing the sluggish kinetics behavior of battery-type carbon negative electrode. Herein, novel 2D defective high-graphitic carbon nanosheets (GNS), which is derived from in-situ catalytic graphitization of 1D nanorods precursor, are presented and employed as negative electrode materials in LICs. The effects of defects contained in the as-prepared samples are further explored by the First-principle calculations, revealing that carbonylation and N-doping (particularly pyridine N) manifest synergistic effect on improving the electronic conductivity and regulating the microstructure. The high reversible capacity accompanied with large plateau capacity and superior rate capability in the half-cell test implies that GNS can be a promised candidate as negative electrode for LICs. Excitingly, the fabricated LICs exhibit high energy density of 112 Wh kg−1 and excellent power density of 19,600 W kg−1, together with outstanding energy density retention of 96.5% after 5000 cycles at 5 A g−1. The defects-controlled in-situ catalytic strategy for preparing GNS may provide a brand-new way for materials design for energy storage.

Size- and Morphology-Dependent Auger Recombination in CsPbBr3 Perovskite Two-Dimensional Nanoplatelets and One-Dimensional Nanorods.

CsPbX3 (X = Cl, Br, I) perovskite nanocrystals (NCs), including zero-dimensional (0D) quantum dots (QDs), one-dimensional (1D) nanorods (NRs), and two-dimensional (2D) nanoplatelets (NPLs), have shown promising performances in light-emitting diode (LED) and lasing applications. However, Auger recombination, one of the key processes that limit their performance, remains poorly understood in CsPbX3 2D NPLs and 1D NRs. We show that the biexciton Auger lifetimes of CsPbBr3 NPLs (NRs) scale linearly with the NPL lateral area (NR length) and deviates from the "universal volume scale law" that has been observed for QDs. These results are consistent with a model in which the Auger recombination rate for 1D NRs and 2D NPLs is a product of binary collision frequency in the nonquantum confined dimension and Auger probability per collision. Comparisons of Auger recombination in CsPbBr3 NCs of different dimensionalities and similar band gaps suggest that Auger probability increases in NCs with a higher number of confined dimensions. Compared to CdSe and PbSe NCs with the same dimensionalities and similar sizes, Auger recombination rates in 0D-2D CsPbBr3 NCs are over 10-fold faster. Fast Auger recombination in CsPbBr3 NCs shows their potentials for Auger-assisted up-conversion and single photon source, while suppressing Auger recombination may further enhance their performances in LED and lasing applications.

Morphology Tailoring of ZnWO4 Crystallites/Architectures and Photoluminescence of the Doped RE3+ Ions (RE = Sm, Eu, Tb, and Dy).

Tartrate (Tar2-) was originally employed in this work as a chelating/structure-directing agent for hydrothermal crystallization of ZnWO4, where the decisive roles of Tar2-/Zn2+/WO42- molar ratio, solution pH (7-10), and the use of ethylene glycol (EG) cosolvent in phase/morphology evolution were deciphered in detail. It was unambiguously manifested that Tar2- may remarkably retard the intrinsically preferred [001] growth of ZnWO4, transform 1D nanorods to 0D nanoparticles and then to 2D platelets, and meanwhile induce face-to-face alignment of the platelets to form spheroidal, ellipsoidal and snowflakelike 3D architectures, where the 2D crystallites were revealed to develop via oriented attachment (colattice) of non-(00l) facets. A lower solution pH and excessive WO42- were clearly shown to enhance and offset the effect of Tar2-, which led to ellipsoidal assemblies of substantially larger 2D crystallites and suppressed 2D growth/3D assembly of ZnWO4 crystallites, respectively. With the spheroidal architectures for example, doping ZnWO4 with RE3+ yielded (Zn0.98RE0.02)WO4 phosphors (RE = Sm, Eu, Tb, and Dy, respectively) that show luminescence overlapped from the typical linelike and broad-band (∼350-700 nm) emissions of RE3+ and WO6, respectively. The luminescence color of the sample was found to drift away from the blue corner of the CIE chromaticity diagram with RE3+ doping and to be dependent on the type of RE3+.

Morphology selective construction of β-cyclodextrin functionalized Fe3O4-Bi2WO6 nanocomposite with superior adsorptivity and visible-light-driven catalytic activity

Controlled growth of Bi2WO6 nanorods with exposed [0 0 1] facets and the fabrication of an Fe3O4-Bi2WO6 magnetic composite by a microwave-assisted polyol process, were achieved in this study. The adsorptivity and photocatalytic performance of the composite toward sunset yellow dye degradation were greatly enhanced by the β-cyclodextrin cavities on its surface, firmly anchored through a cetyltrimethylammonium bromide linkage. A series of examinations and characterizations were carried out to determine the influence of various factors on the morphological modulation-photocatalytic behavior of the pure Bi2WO6 prior to final functionalization. Changing the pH of the precursor solution impacted the formation of 0D, 2D, and 3D structures; however, the presence of hexamethylenetetramine surfactant induced the development of 1D nanorod structure. A reasonable crystal growth mechanism was proposed to elucidate the formation process. Conversely, the mechanism of the activity enhancement of β-cyclodextrin functionalized Fe3O4-Bi2WO6, compared to that of the non-functionalized samples, could be realized with the assistance of chemical trapping experiments on sunset yellow, and was confirmed on the colorless antibiotic (sulfamethoxazole). The high performance and durability of this composite can be attributed to the facet-dependent activity, large adsorption capacity due to inclusion interactions, enhanced visible light absorption, and efficient charge separation.

Lead-free high Tc ferroelectric material: Hierarchical Dy-doped ZnO architectures co-assembled by 1D nanorods and 2D nanosheets

High temperature ferroelectricity (Tc ∼435 °C, Ec ∼6.15 kV/cm & Pr ∼0.16 μC/cm2) was observed in a novel 3D hierarchical dysprosium (Dy)-doped ZnO nanorods-nanosheets (NRs-NSs) architecture synthesized using wet chemical co-precipitation method. Such a conclusion was drawn on the experimental confirmation obtained from the temperature variation of real part of dielectric constant and the room temperature P–E hysteresis loop. Dy3+ doping strongly modified the morphology of ZnO from nanotaper to hierarchical NRs-NSs architecture. Lattice strain (ε), crystallite size (L), deformation stress (σ), and deformation energy density (u) of both pristine nanotapers and 3D hierarchical Dy-ZnO NRs-NSs architectures were evaluated using line broadening analysis followed by the Debye-Scherrer and Williamson-Hall methods. Temperature variation of real component of dielectric constant (ε′) for Dy-doped ZnO NRs-NSs architecture attains a maxima (ε′m ∼34,500) at ferro-to para-electric transition temperature, Tc ∼435 °C. Temperature dependent complex component of dielectric constant (ε''), tangent dielectric loss (tan δ) and ac conductivity (σ) were found to increase with rise in temperature. The frequency dependent dispersion plots of dielectric properties of Dy-ZnO NPs showed a decrease in dielectric constant and tangent loss with increase in frequency whereas ac conductivity showed an opposite trend. The Dy-doped ZnO NRs-NSs architectures exhibit feeble ferroelectricity with a remnant polarization (Pr) of 0.16 μC/cm2 and a coercive field (Ec) of 6.15 kV/cm at room temperature. Moreover, the novel Dy-doped nanorods-nanosheets architectures with high temperature ferroelectricity will pave the pathway towards designing futuristic material in the field of low-power and wide-temperature ferroelectric based memory devices.

One-dimensional MoO3/Pd nanocomposite electrodes for high performance supercapacitors

One-dimensional (1D) nanostructures are the exemplary host for fabricating active electrode material for supercapacitors as they have large specific surface area, robust adsorption/desorption capability and outstanding thermal stability, which could assist as support and promoter to anchor noble metal nanoparticles with enhanced electrochemical properties. Herein, pure and MoO3/Pd nanocomposites have been synthesized by simple hydrothermal method. The XRD spectrum of synthesized powder exhibited orthorhombic α-MoO3 structure and the calculated average crystallite sizes are 42 nm and 33 nm for pure and MoO3/Pd nanocomposites respectively. The Pd nanoparticles plays a crucial role in controlling the structure. The SEM images showed 1D nanorods like structure with a size of about 100 nm dia and few micrometer length. The TEM images confirm the Pd nanoparticles are incorporated into the 1D MoO3 nanorods. The electrochemical properties of pure and MoO3/Pd 1D nanocomposite electrodes showed pseudocapacitive nature. The MoO3/Pd electrode exhibited high specific capacitance of 501 F g−1 at a current density of 1 mA g−1 with good cycling stability. The high specific capacitance of newly fabricated MoO3/Pd nanocomposite electrode is mainly associated with the synergetic effect between Pd nanoparticles and MoO3 nanorods.

Performance enhancement of hole-transport material free perovskite solar cells with TiO2 nanorods modified with SiO2/NaYF4:Yb,Er@SiO2 for upconversion and charge recombination suppression

Abstract Hole-transport material-free (HTM-free) perovskite solar cells (PSCs) have the advantages of low manufacturing cost and excellent stability, however, the power conversion efficiencies (PCEs) of these PSCs are relatively low due to the high recombination rate at charge transport interface contacts. Herein, a novel bilayer electron-transport scaffold of SiO2/NaYF4:Yb,Er@SiO2 modified TiO2 nanorods was designed to improve the performance of HTM-free PSCs. Facilitated by the 1D nanorods structure of underneath TiO2 scaffold, photogenerated charges can be quickly transported out of perovskite film with reduced recombination, and the NaYF4:Yb,Er@SiO2 insulating capping layer can further inhibit the charge recombination by removing charge shorting pathways caused by the tangle of TiO2 nanorods with carbon back contact. Moreover, NaYF4:Yb,Er can upconvert near-infrared light into visible region that can be directly used by perovskite materials to improve the current density of corresponding PSCs. Our PSCs have an average PCE of 14.01 ± 0.53%. We demonstrated that up-conversion of light at 980 nm was possible but up-conversion made no statistical improvement in performance.

Exciton Binding Energy of Two-Dimensional Highly Luminescent Colloidal Nanostructures Determined from Combined Optical and Photoacoustic Spectroscopies.

Reduced dimensionality of structures such as 0D quantum dots, 1D nanorods, and 2D nanoplatelets is predicted to favor the creation of tightly bound excitons stable at room temperature, making experimental determination of the exciton binding energy ( R x) crucial for evaluating the performance of semiconductor nanoparticles. We propose a fully optical approach for R x determination based on a complementary combination of photoacoustic and transmission spectra, using 5.5, 4.5, and 3.5 ML CdSe nanoplatelets as a benchmark system. The absence of excitonic features in photoacoustic spectra allows for probing the band-to-band transition, leading to the band gap determination. Such an unusual effect is explained by efficient re-emission of the absorbed radiation typical for high quantum yield structures, keeping the crystal lattice from excess phonon generation. The determined exciton binding energy for CdSe nanoplatelets ranges from 130 to 230 meV, confirming the presence of robust excitons in highly confined 2D systems.

Determinant factors of photocatalytic hydrogen evolution activity for Schiff-base conjugated polymers

Conjugated polymers are promising catalysts for photocatalytic hydrogen evolution (PHE) from water. Here, a series of imine-linked conjugated polymers were synthesized via Schiff-base condensation using an easy and low-temperature protocol with cheap raw materials and green solvent. Several readily available diaminobenzene with different amino substitution positions on the phenyl ring were used to react with terephthalaldehyde, leading to formation of polymers varying from one dimensional (1D) nanorods to two dimensional (2D) and three-dimensional (3D) networks. The obtained polymer with 1D crystalline structure was found to show the highest hydrogen production rate at ~24.3 μmol/h under visible light irradiation (λ > 420 nm) without adding any additional metal co-catalysts. Detailed analysis of the structure, morphology and photoelectron-chemical properties of these as-synthesized polymers leads to the conclusion that 1D nanorods and high LUMO (the lowest unoccupied molecular orbital) play more important roles than large conjugation and surface area in improving the PHE capacity of polymer. This study illustrated a protocol for the production of metal-free photocatalyst synthesized using cheap and green solvent at low-temperature.

Sol-Gel Assisted Isotropic Morphological Progression in Nanostructured MoO₃ and Allied Investigations on Photocatalytic Dye-Degradation.

We report tunable-morphology oriented facile yet scalable route to synthesize 1D (nanorod) and 2D (nanobelt) MoO₃ nanostructures at gram scale using conventional as well as sonochemistry assisted sol-gel technique. The structural, morphological and optical properties of the samples can be befittingly altered by varying the synthesis protocol. The resultant orthorhombic MoO₃ nanomorphs demonstrated efficient and expeditious photocatalytic degradation of the pollutant dye, Methylene Blue (MB). We have observed that appreciable photocatalytic MB dye-degradation can be accomplished within 30 minutes with high rate constants of 0.0786 min-1 and 0.233 min-1 for rod and belt-like MoO₃-nanostructures, respectively. The pilot results indicate that the resultant MoO₃ nanomorphs can be potentially used as solar light driven industrial photocatalyst material with their intrinsic photostability.

Highly Efficient g‐C3N4 Nanorods with Dual Active Sites as an Electrocatalyst for the Oxygen Evolution Reaction

AbstractFinding metal‐free, carbon‐based, highly active, and durable electrocatalyst for oxygen evolution reaction (OER) is essential for the development of electrochemical energy storage and conversion systems. Herein, we report the synthesis of graphitic carbon nitride (g‐C3N4) nanorods using a hydrothermal method. The transformation of bulk g‐C3N4 (denoted as g‐B‐CN) to g‐C3N4 1D nanorods (denoted as g‐CN) endowed the material with abundant active sites, increased electrochemical active surface area, and enhanced charge transfer. g‐CN exhibited high activity and durability in catalyzing the OER. The optimized g‐CN achieved a current density of 10 mA cm−2 at an overpotential of 316 mV vs. RHE in 1 M KOH, with a Tafel slope of 125 mV dec−1. The high catalytic performance of g‐CN is mainly attributed to the abundantly exposed unique active sites originatingfrom the 1D morphology and the presence of an oxidized pyridinic nitrogen; elucidating the important role of elaborate morphology tailoring and co‐doping of heteroatoms in catalyzing the OER.

NH3-induced morphological evolution of organohalide perovskites from three-dimensional microcubes to one-dimensional nanorod aggregates and their electrochemical performance

Sensitive nature of organic-inorganic hybrid perovskite material provides an opportunity to turn its electrochemical property. Herein, the conversion process from three-dimensional (3D) CH3NH3PbI3 (MAPbI3) microcubes to one-dimensional (1D) nanorod aggregates was reported by NH3 post-treatment for 30 min, which enhanced the carrier mobility (36.91 cm2/V) and Li-ion diffusion coefficient (5.26 × 10−9 cm2 s−1) and narrowed the optical band gap (1.385 eV) of MAPbI3 nanorod aggregates. The morphology evolution of 3D MAPbI3 crystals and 1D MAPbI3 nanorod rebuilding mechanism induced by NH3 have been investigated and proposed. In addition, compared with samples without NH3 treatment, 1D nanorod aggregates exhibited the improved electrochemical performances including capacity (from 53 mA h g−1 to 243 mA h g−1) and cycle stability (132 mA h g−1, 300th cycle) which are ascribed to the improved electronic properties and special 1D microstructure.

Ultra-Low Noble Metal Containing One-Dimensional Nanorods: High Performance Oer Electrocatalyst for Acid Mediated PEM Based Water Electrolysis

The rising concerns of rapidly depleting conventional fossil fuels combined with the alarming global warming signs have made it imperative to explore the development of alternative clean, environmentally friendly and sustainable energy sources for alleviating our perpetual reliance on the high carbon foot print of fossil fuels. In order to achieve this goal, hydrogen (H2), a non-carbonaceous high efficiency fuel having higher energy density than petroleum based energy sources has garnered much attention over the years.1-2 Generation of clean and sustainable hydrogen via proton exchange membrane (PEM) based acid mediated water electrolysis is one of the most advantageous, efficient and reliable hydrogen production technologies.3-4 Though promising, commercial implementation of this technology is hindered by the need for expensive and environmentally scarce electrocatalysts belonging to the platinum group metals (PGM) such as Pt, RuO2, IrO2. PGM based electro-catalysts albeit known for their excellent electrochemical response for oxygen evolution reaction (OER), are also characterized by sluggish reaction kinetics.1, 5 Therefore, there is a need to identify, synthesize and develop novel reduced noble metal containing electro-catalysts displaying excellent electro-catalytic activity and robust long term electrochemical stability similar/superior to IrO2-the state of the art OER electrocatalyst in highly acidic operating conditions of OER. In addition, generating one-dimensional (1D) morphologies such as nanowires (NWs), nanorods (NRs) and nanotubes (NTs) will improve OER kinetics and activity for water splitting due to their inherent high electro-catalytic surface area, large aspect ratios (length-to-width ratio) and facile electron transport channeled by the 1D nanorod arrays.6 Consequently, in the present study, aided by our theoretical first principles electronic structure and reaction energy calculations, we have explored reduced noble metal containing 1D nanorod morphology of F substituted earth abundant transition metal oxide based electrocatalyst compositions. The as-synthesized 1D electrocatalyst system exhibit significantly lower charge transfer resistance (Rct) (2.5 Ω.cm2) than benchmark IrO2 (41 Ω.cm2) and other PGM based OER catalysts. In addition, the 1D electrocatalyst system display remarkable activity yielding a current density of ~ 10 mA/cm2 at a low over-potential of ~200mV. The 1D vertical channels of nanorods also provide a facile electron transport contributing to excellent electrochemical OER performance with significantly higher mass activity (40 Ag-1), turnover frequency (TOF~0.010 S-1) and higher electrochemically active surface area (ECSA~700 m2g-1) than the benchmark IrO2. Further, chronoamperometry tests in 1N H2SO4 exhibit minimal current density loss, indicating good electrochemical stability attesting to the promise of this 1D nanorod morphology of the electrocatalyst system for PEM water splitting. Results of these studies will be presented and discussed. Acknowledgements: Financial support of NSF-CBET grant# 1511390, Edward R. Weidlein Chair Professorship funds, Center for Energy Graduate Student Fellowship and the Center for Complex Engineered Multifunctional Materials (CCEMM), University of Pittsburgh is acknowledged.

Cadmium sulfide nanostructures: Influence of morphology on the photocatalytic degradation of erioglaucine and hydrogen generation

Size and shape of inorganic materials are known to have great effects on their physical and chemical properties. Here, for the first time we report the visible light driven photocatalytic degradation of erioglaucine – a stable organic dye molecule in the presence of chemically synthesized nanoscale CdS with 1D (nanorods), 2D (nanosheets) and 3D (hierarchical) morphology. Visible light driven photocatalytic degradation efficiency of both 1D and 3D CdS in the removal of erioglaucine are identical. Surprisingly, with 5 min of sonication, the highly crystalline 3D CdS stacked with many thin nanowires containing numerous active surface sites exhibited four-fold enhanced photodegradation efficiency in comparison to 1D and 2D CdS. Scavenger studies revealed that electrons and superoxide radicals are primary reactive species involved in the photodegradation of erioglaucine, while cyclic photodegradation studies revealed the good stability of 3D CdS against photocorrosion. Further, the photocatalytic hydrogen evolution studies also revealed the excellent activity of 3D CdS in comparison to 1D and 2D CdS. Thus, we find that the morphology indeed influences the photocatalytic activity. These results reveal that 3D CdS nanostructures investigated in the present work are efficient photocatalysts that could be fine-tuned for both environmental remediation and hydrogen generation applications.

How aluminum changed the world: A metallurgical revolution through technological and cultural perspectives

The history of aluminum is rather short since it was discovered only in the nineteenth century, yet it has become an important part of everyday life. This article reviews the history of aluminum through technological breakthroughs as well as from cultural and social perspectives, beginning with its discovery, through the nineteenth and twentieth centuries until today; and aims to suggest possible future trends and applications for aluminum alloys. Aluminum has a high strength-to-weight ratio combined with excellent thermal conductivity and good corrosion resistance. Therefore, aluminum is an attractive material for many applications, including transportation, electrical and packaging industries, architecture, and food industries. It is also a recyclable metal, which provides both environmental and economic advantages. The commercial use of aluminum started at the end of the nineteenth century and continues to grow today with the development of new advanced aluminum alloys. Consequently, from a cultural perspective, aluminum is considered a symbol of modernity. Technological breakthroughs generate economic growth and social benefits. Present applications of aluminum include new choices, such as 3D printing, composite materials, nano-rods, biomedicine devices and aerospace uses. Based on the excellent properties of aluminum, its low price, combined with its significant scrap value and a growing recycling market, as well as its accelerating global production, it is expected that the aluminum industries will considerably grow through the twenty-first century and aluminum will continue to be a major part of our everyday culture. Therefore, based on the increasing growth of aluminum production and consumption, additional research and development effort is needed in the following years to minimize the negative environmental side effects associated with the technological developments related to aluminum production and at the same time creating further technological innovation.

Hierarchical Sm-doped ZnO nanorod–nanosheet architecture: dielectric and ferroelectric studies

A novel hierarchical samarium (Sm)-doped ZnO nanorod–nanosheet architecture with high-temperature ferroelectricity (Tc ~ 110 °C, Ec ~ 3.64 kV/cm and Pr ~ 0.08 μC/cm2) have been developed here using wet chemical co-precipitation method. In this study, we show the origin of ferroelectric behavior in Sm-doped ZnO product and study the effect of frequency and temperature on its dielectric characteristics. Interestingly as an impact of Sm-doping, the morphology of pristine ZnO got evolved from 1D nanopencils (NPCs) to 3D hierarchical architectures composed of both 1D nanorods (NRs) and 2D nanosheets (NSs). Crystallite size (L), lattice strain (e), deformation stress (σ), and uniform energy density (u) of both isolated 1D NPCs and 3D hierarchical NR–NS architectures were evaluated using the Debye–Scherrer and Williamson–Hall methods. Temperature-dependent real dielectric constant (e′) revealed a ferro- to para-electric transition peak at 110 °C. Temperature-dependent complex dielectric constant (e″), dielectric loss (tan δ) and ac conductivity (σ) were found to increase with temperature. The frequency-dependent dispersion curves of dielectric properties showed an increase in ac conductivity with increase in frequency whereas complex part of dielectric constant and dielectric loss showed an opposite trend. The Sm-doped ZnO NR–NS architecture exhibits weak ferroelectricity with a coercive field (Ec) of 3.64 kV/cm and a remnant polarization (Pr) of 0.08 μC/cm2 at room temperature. Moreover, the high-temperature ferroelectricity established in this work will make Sm–ZnO a futuristic material in the field of designing memory devices.

3D α-Fe2O3 nanorods arrays@graphene oxide nanosheets as sensing materials for improved gas sensitivity

Hybridizing nanostructured metal oxides with grapheme oxide (GO) is highly desirable for the improvement of gas sensing performance of gas sensors. Herein, we develop an in situ fluorine directed solution process combined with heat treatment to grow highly ordered, porous α-Fe2O3 nanorods arrays (NRAs) onto graphene oxide (GO) sheets, resulting in flexible three-dimensional nanostructures. The α-Fe2O3 NRAs have heights of ∼50 nm and widths of 10–20 nm, which are densely and vertically attached to both sides of GO sheets, thereby generating an interesting “blanket-like” geometry. When tested as sensing materials for gas sensors, the nanocomposite displays a high sensitivity of 19.14 toward 50 ppm acetone at a work temperature of 220 °C, which was 5.4 times of that of α-Fe2O3. Even after 50 days, a stable sensitivity as high as 18.9 toward 50 ppm acetone could be maintained. The improved high sensitivity, fast response and recovery, and extraordinary stability of GO/α-Fe2O3 can be attributed to the highly ordered, porous structure and the synergistic effect between α-Fe2O3 and GO.

Solvent-Driven Reversible Phase Transition of a Pillared Metal-Organic Framework.

Over the last decade, the controllable reversible phase transition of functional materials has received growing interest as it shows unique suitability for various technological applications. Although many metal-organic frameworks (MOFs) possess a lamellar structure, the reversible structural transformation of MOFs between their three-dimensional (3D) phase and two-dimensional (2D) phase remains a largely unexplored area. Herein, we report for the first time a europium MOF with unprecedented reversible morphology in different solvents at room temperature. This europium MOF displayed a 3D nanorod morphology in organic solvent and a 2D nanobelt architecture in water. As a proof of concept for potential applications of this reversible-phase-transition MOF, we were able to use a delamination recovery method to load dye molecules that previously could not be loaded into europium MOFs.

Development of dye sensitized TiO2 thin films for efficient energy harvesting

In the present investigation, we are reporting development of 3D nanoflower like architecture of TiO2 for dye sensitized solar cell (DSSC). Initially, TiO2 thin films were synthesized by using a simple hydrothermal approach. The effect of deposition time on the optostructural, morphological, compositional and photoelectrochemical properties of TiO2 thin films was studied. The optical study reveals direct and allowed transition with band gap variation in the range of 2.4–3.0 eV. The XRD pattern confirms rutile tetragonal crystal structure with crystallite size ranging from 20 to 50 nm. The morphological analysis shows presence of 1D nanorods assembling to give a 3D nanoflower like architecture. The compositional data confirms the presence of titanium and oxygen in the 1:2 with respective oxidation state. HRTEM images are in good agreement with SEM images confirming single crystalline nature of TiO2 thin films. As deposited TiO2 thin films are sensitized with different concentrations of Betanin dye. This natural dye sensitized TiO2 is used as photoelectrode to determine the photovoltaic performance. The purity and structure of betanin dye was determined by LC-MS and FT-IR. The PEC performance increases from 5.82% to 14.21% with increase in deposition time. Further in order to study the charge transport mechanism EIS is done. The stability study of T-9 sample is done to confirm the stability.