Reduction In Optical Band Gap Research Articles

Substituent Controlled Tunable Fluorescence from Green to Red and pH Stimuli‐Induced Reversible Fluorescence Switching in Triphenylamine–Quinoxaline Derivatives

A series of triphenylamine‐quinoxaline donor‐acceptor (bipolar) compounds (TPA‐QH, TPA‐QMe, TPA‐QCOOH and TPA‐QNO2) with different substituents were synthesized and investigated their fluorescence properties, including stimuli‐induced fluorescence responses in solution and the solid‐state. Single crystal structural analysis revealed non‐planar molecular conformation, substituent controlled intermolecular interactions and molecular packing in the crystal lattice. TPA‐QH, TPA‐QMe, TPA‐QCOOH and TPA‐QNO2 showed tunable solid‐state emission from green to red. TPA‐QH showed strong fluorescence at 487 nm (quantum yield (Φf) = 28.3%) whereas NO2 substituted TPA‐QNO2 exhibited relatively weak fluorescence at 610 nm (Φf = 4.3%). Density functional theoretical (DFT) calculations also indicated reduction of optical bandgap with substituting electron withdrawing group. The donor‐acceptor structure with intramolecular charge transfer (ICT) resulted solvent polarity dependent fluorescence tuning. The presence of acid responsive quinoxaline group was utilized to demonstrate pH‐responsive fluorescence switching and dual state fluorescence was utilized for fabricating rewritable fluorescent platform. Thus, the present study provides a structural insight to develop dual state emissive triphenylamine–quinoxaline based bipolar materials for optoelectronic applications.

Optical, magnetic and defect studies of Ni2+ doped SrSnO3 nanostructures

The induced ferromagnetic behaviour and defect analysis of the undoped, Ni doped SrSnO3 nanostructures are examined. The undoped and Ni doped SrSnO3 (SSO) nanostructures crystallized in the orthorhombic perovskite structure, and show local structural disorders on vibrational spectroscopic analysis. The electron micrographs are witnessed rod type morphology for pure SrSnO3 and corals for Ni doped compounds. The oxidation states of elements and presence of oxygen vacancies are identified. The sharp optical absorption behaviour resulted in reduction of optical band gap. Positron annihilation spectroscopy (PAS) studies reveal the presence of site-specific intrinsic defects of considerable concentration and their consequential effect on doping. PAS significantly showed that Schottky-type VSn and VSr-XO complexes in undoped SSO. The addition of Ni2+ results in the reduction of VSr–O and the formation of Ni2+-VO-Ni2+ defect complexes. The EPR spectra show the signal with g value of 2.2432. The appearance of RT ferromagnetism could be attributed to the defects, F-center exchange (FCE) interactions in Ni-doped SSO nanostructures.

Improved electrochemical performance of bio-derived plasticized starch/ reduced graphene oxide/ molybdenum disulfide ternary nanocomposite for flexible energy storage applications

A ternary nanocomposite of plasticized starch (PS), reduced graphene oxide (rGO), and molybdenum disulfide (MoS2) was prepared via a solution casting process, with MoS2 concentrations ranging from 0.25 to 1.00 wt%. The structural, surface morphological, optical, and electrochemical properties of the nanocomposites were studied. FTIR analysis reveals the formation of new chemical bonds between PS, rGO, and MoS2, indicating strong interactions among them. The XRD analysis showed a reduction in the crystallinity of the nanocomposite from 40 to 21% due to the incorporation of nanofiller. FESEM micrograph showed an increment of the surface roughness due to the incorporation of rGO-MoS2 layers. UV–vis spectroscopy demonstrated a reduction of optical bandgap from 4.71 to 2.90 eV, resulting from enhanced charge transfer between the layers and defect states due to the addition of nanofillers. The incorporation of MoS2 increase the specific capacitance of the PS from 2.78 to 124.98 F g−1 at a current density of 0.10 mA g−1. The EIS analysis revealed that the nanofiller significantly reduces the charge transfer resistance from 4574 to 0 Ω, facilitating the ion transportation between the layers. The PS/rGO/MoS2 nanocomposite also exhibited excellent stability, retaining about 85% of its capacitance up to 10,000 charging-discharging cycles. These biocompatible polymer-based nanocomposites with improved electrochemical performance synthesized from an easy and economical route may offer a promising direction to fabricate a nature-friendly electrode material for energy storage applications.

Remarkable Isomer Effect on the Performance of Fully Non‐Fused Non‐Fullerene Acceptors in Near‐Infrared Organic Photodetectors

AbstractTwo fully non‐fused small‐molecule acceptors BTIC‐1 and BTIC‐2 are reported for application in near‐infrared organic photodetectors (NIR OPDs). Both acceptors contain the same conjugated backbone but differing sidechain regiochemistry, affording significant differences in their optical properties. The head‐to‐head arrangement of BTIC‐2 results in a reduction of optical band gap of 0.17 eV compared to BTIC‐1, which contains a head‐to‐tail arrangement, with absorption spanning the visible and near‐IR regions up to 900 nm. These differences are rationalized on the basis of non‐covalent intramolecular interactions facilitating a more co‐planar conformation for BTIC‐2. OPDs based on PM6:BTIC‐2 deliver a low dark current density of 2.4 × 10−7 A cm−2, leading to a superior specific detectivity of 1.7 × 1011 Jones at 828 nm at ‐2 V. The optimized device exhibits an ultrafast photo response of 2.6 µs and a high ‐3 dB cut‐off frequency of 130 kHz. This work demonstrates that fully non‐fused small‐molecule acceptors offer competitive device performance for NIR OPDs compared to fused‐ring electron acceptors, but with reduced synthetic complexity. Furthermore, the study presents an efficient strategy to enhance device performance by varying conformational locks.

Effect of Azo Dye on Electro-Optic and Optical Band Gap Characteristics in ZnO Nanoparticles Induced Vertically Aligned Liquid Crystal Cells

Alignment of liquid crystal (LC) molecules in vertical direction is the most promising and interesting aspect for display devices in view of scientific and technological growth. Moreover, in accordance with the photovoltaic device applications, liquid crystals (LCs) show numerous applications. In the present work, the impact of dye as dopant with appropriate amount, over the electro-optic (E-O) and band gap properties as well as phase behaviour of vertically aligned liquid crystals (VALCs) has been studied and discussed. Initially, zinc oxide (ZnO) nanoparticles (NPs) were mixed to induce the vertical alignment (VA) in confined cell. Then, to prepare the dye doped LC sample, 0.125% of azo dye as dopant was uniformly mixed in the host sample. The results showed enhanced E-O characteristics with reduction in optical band gap as calculated using UV Visible study in 0.125% dye doped cell as compared to host sample cell.

Enhanced luminescence sensing performance and increased intrachain order in blended films of P3HT and cellulose nanocrystals

Blended films comprising poly(butyl acrylate) (PBA)-grafted cellulose nanocrystals (CNCs) and poly(3-hexylthiophene) (P3HT), exhibited more intense photoluminescence (PL) and longer PL emission lifetimes compared to pristine P3HT films. Optical absorption and photoluminescence spectra indicated reduced torsional disorder i.e. enhanced backbone planarity in the P3HT@CNC blended composites compared to the bare P3HT. Such molecule-level geometrical modification resulted in both smaller interchain and higher intrachain exciton bandwidth in the blended composites compared to the bare P3HT, because of reduced interchain interactions and enhanced intrachain order. These results indicate a potential switch of the aggregation behavior from dominant H-aggregates to J-aggregates, supported by Raman spectroscopy. The reorganization of micromolecular structure and concomitant macroscopic aggregation of the conjugated polymer chains resulted in a longer conjugation length for the P3HT@CNC blended composites compared to the bare P3HT. Additionally, this nanoscale morphological change produced a reduction in the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy gap of the blends, evidenced from optical absorption spectra. Classical molecular dynamics simulation studies predicted the probability of enhanced planarity in the polymer backbone following interactions with CNC surfaces. Theoretical results from density functional theory calculations corroborate the experimentally observed reduction of optical bandgap in the blends compared to bare P3HT. The blended composite outperformed the bare P3HT in nitro-group PL sensing tests with a pronounced difference in the reaction kinetics. While the PL quenching dynamics for bare P3HT followed Stern–Volmer kinetics, the P3HT@CNC blended composite exhibited a drastic deviation from the same. This work shows the potential of a functionalized rod-like biopolymer in tuning the optoelectronic properties of a technologically important polymeric organic semiconductor through control of the nanoscale morphology.

Structural, optical, and electrical properties of V2O5 thin films: Nitrogen implantation and the role of different substrates

This report investigates the effect of substrate and nitrogen (16 keV N+) ion implantation on the structural, morphological, compositional, and electrical properties of V2O5 thin films which are grown by thermal evaporation on various substrates, including glass, Si, and sapphire (termed V2O5:Gl, V2O5:Si, and V2O5:Sp, respectively). Structural analysis showed the formation of the mixed (α, and β-V2O5) phases on all substrates; however, the β-V2O5 phase is highly dominant in the V2O5:G and V2O5:Si samples. A deformation in the β-phase of V2O5 thin film under ion implantation-induced strain results in a change of crystallite size. Irradiation suppresses XRD peaks in relative intensities, indicating partial amorphization of the film with defect formation. Microstructural analysis confirmed the formation of uniform-sized nanorods for V2O5:Si, whereas isolated crystallites were formed for other types of substrates. Thermal conductivity may influence the size and shapes of V2O5 crystallite forms on different surfaces. Silicon absorbs heat more effectively than sapphire or glass, resulting in nanorod formation. A decrease in optical bandgap and electrical conduction has been observed due to increased oxygen vacancies, induced electron scattering, and trapping centres on N+ implantation. The present study thus offers the unique advantage of simultaneous reduction in optical band-gap and conductance of V2O5 thin films, which is important for optoelectronic applications.

A comparative study on the structural, optical, and magnetic behavior of transition metal (Co and Mn) ions substituted Cr2O3 nanoparticles

A comparative study on structural, optical, and magnetic properties of TMxCr2−xO3 (TM = Co and Mn) nanoparticles was synthesized using a simple co-precipitation method with subsequent heat treatment. The structural characterizations of as-prepared nanoparticles were performed using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. XRD pattern revealed the formation of rhombohedral Cr2O3 phase with space group R3¯c. The FTIR spectra illustrated the shifting of absorption bands of Cr2O3 nanoparticles with Co and Mn substitution due to strain induced within the crystal lattice. X-ray photoelectron spectroscopy (XPS) confirmed the presence of a mixed oxidation state of Cr and oxygen defects in the prepared nanoparticles. Furthermore, XPS spectra also demonstrated the presence of Co and Mn having +2 oxidation state. The reduction in optical band gap of host material was observed with Co and Mn substitution. The magnetic properties of as-synthesized nanoparticles were recorded using a SQUID magnetometer and temperature-dependent magnetic measurements illustrated the decrease of Neel temperature with Co and Mn substitution. It was also demonstrated that magnetization increases below about ∼ 120 K due to spin canting and spin frustration for both TM ions substituted Cr2O3 nanoparticles and is fitted using the 3D spin-wave model with Curie-Weiss law. The magnetic studies revealed the mixed paramagnetic (PM) and antiferromagnetic (AFM) order at room temperature and AFM mix with ferromagnetic (FM) order at low temperature explained using the bound magnetic polarons (BMP) model.

Implanting TiO2 @MoS2/BiVO4 nanocomposites via sonochemically assisted photoinduced charge carriers promotes highly efficient photocatalytic removal of tetracycline

In recent decades, antibiotics have been identified in the aquatic environment, raising serious concerns. This study demonstrates antibiotic degradation via a photocatalytic technique through novel TiO2 @MoS2/BiVO4 nanocomposites created using a simple hydrothermal method in the absence or presence of ultrasonic irradiation. Several approaches were applied to characterize the structural, morphological, electrical, and optical properties of the as-synthesized catalysts. It confirmed the successful heterostructure formation with superior properties compared to bare samples. Furthermore, tetracycline antibiotics were investigated for photocatalytic degradation. The results reveal that the TiO2 @ 2 M/8B (US) composite shows outperformance compared to other composites regarding photocatalytic activity toward tetracycline degradation. After five cycles, TiO2 @ 2 M/8B (US) and TiO2 @ 2 M/8B (NUS) exhibit sufficient stability for tetracycline degradation. Throughout the degradation process, superoxide and hydroxyl radicals were found to be the key active species. According to the results, TiO2 @ 2 M/8B (US) has much better catalytic activity than TiO2 @ 2 M/8B (NUS). The synergistic effect of ultrasonic irradiation and the TiO2 optical bandgap reduction by stacking BiVO4 and MoS2 is responsible for this remarkable photocatalytic improvement.

Preferential grain growth, tunable bandgap and topological insulating to bulk state modification induced via Ag ion irradiation in antimony telluride nanostructured thin film

Ion irradiation has been an important technique to alter the physical properties of materials for desired applications. Sb2Te3 thin films deposited via vacuum thermal evaporation procedure are Ag ion irradiated at various fluences. Preferential grain growth along the [104] direction and reduction in optical bandgap from 1.37 eV for unirradiated thin films to 1.14 eV for irradiated thin films is noticed. The value of the Seebeck coefficient decreases with ion fluences 1 × 1010 and 1 × 1012 ions/cm2 owing to the variation in carrier concentration as evident from the Hall measurements. Interestingly, the value of the Seebeck coefficient of the pristine film (457 μV/K at 313 K) is higher than previously reported value in these materials. The study might be catchy to tailor the physical properties of alloys for thermophotovoltaic applications.

Investigating structural, electronic, magnetic, and optical properties of Co-doped and Co-X (X = Fe, Mn) co-doped MoS2 for optoelectronic applications.

We employ first-principle calculations to investigate structural, electronic, magnetic, and optical properties of cobalt and Co-X (X = Fe, Mn) co-doped MoS2. Result demonstrates that pure MoS2 is nonmagnetic, while Co and Co-Fe/Mn co-doping brings magnetism into MoS2 with magnetic moment values of 0 [Formula: see text], 2.022 [Formula: see text], 3.906 [Formula: see text], and 3.643 [Formula: see text] respectively. d states of dopants and p-d hybridization bring significant improvements in electronic properties of MoS2. Novelty of current work lies not only in origin of magnetism in the proposed materials but also in absorption spectra which show blueshift. We notice reduction in optical band gap with Co and Co-Fe/Mn co-doping. Enhanced absorption and conductivity with decrease in reflectivity illustrate potential uses of these materials for revolutionizing future of optoelectronics, spintronics, magneto-optics, and photonics devices. Moreover, crossroads of MoS2 and allied materials may further explore new avenues in sensing, artificial intelligence, and miniaturization of existing technology.

Experimental and computational investigation on Polyaniline/Zno nanocomposite for dye adsorption

Present study reports computational simulations and experimental procedures for the synthesis of Polyaniline/Zinc oxide (PAni/ZnO) nanocomposite and investigate its efficiency as an adsorbent for Methyl Orange (MeO) dye. The nanocomposite was fabricated using a chemical oxidative polymerization method and characterized through FT-IR, Powder XRD and FE-SEM spectroscopic techniques. There is substantial reduction in optical band gap of the nanocomposite in comparison to pristine polymer and ZnO unit. Red shift in the absorption spectrum confirms the suitability of the proposed composite for sensing and adsorption. Effect of pH/contact time/adsorbent dosage and dye concentration on the adsorption process has been elucidated in detail. Kinetics and thermodynamics of dye adsorption have been understood through calculation of adsorption energy and isotherms. The novel nanocomposite proposed here stands the test of rigorous computational and experimental investigations to establish its efficacy as a potential adsorbent for environment remediation.

Amelioration of rectification properties of CuO nanostructures using surface modification

In the current work, CuO spherical and rod-shaped particles has been synthesized with help of co-precipitation technique. XRD studies reveal the presence of phase reversal of CuOH to CuO with single phase monoclinic structure. FT-IR analysis authenticates the occurrence of copper oxide nanostructures with the removal of nitrogen-based vibrations and organic species. FESEM micrographs reveals the formation of interlinked spherical and rod like structured CuO particles with an average size 57 nm. UV–Visible analysis unveils the optical bandgap reduction from 2.62 to 2.04 eV during annealing. XPS analysis portrays the dominant appearance of Cu2+ which confirms the formation of CuO particles inconsistence with XRD and FT-IR results. The improved performance of the prepared photodiode is obtained from I–V characteristics. The excellent optoelectronic properties of the developed photodiode make them suitable for future nano-electronics.

An experimental and simulation evaluation of the structural, morphological and optical characters of ZnO-based nano-fibers doped with Ag and ZrO2

This research elucidates the elaborative investigation into the ZnO-based nano-fibers. The outcomes of the study are expounded on two fronts that is (i) - experimental synthesis and (ii) – simulation-based analysis. The objectives are attained by the experimental synthesis of ZnO, ZnO-Ag, ZnO-ZrO2 and ZnO-Ag-ZrO2 nano-fibers. The experimental findings are further substantiated by the application of the soft of Quantumwise Atomistix Toolkit (ATK-VNL), mimicking numerous experimental parameters. The prepared samples are rigorously studied to assemble the structural information, morphological patterns, functional bonding and to explore the optical characters. Furthermore, the attributes such as, density of states, transmission spectrum and IV-curves are illuminated by the launch of ATK-VNL simulation tool. The outcomes of the research indicate the superior performance of ZnO-Ag-ZrO2 nano-fibers in comparison to the other rival composites. The XRD patterns of the highlighted sample reveals mixture of crystallographic structure corresponding the diffraction angles 2θ. The SEM micrograph of fracture surface indicates the prevalence of improved crystallinity in ZnO-Ag-ZrO2 samples. Moreover, the most profound reduction in optical band gap is witnessed to be associated with the sample prepared by the doping of silver and zirconia. The comparative study of density of states of simulated ZnO-Ag-ZrO2 device shows the presence of novel energy levels below and above the fermi level which are found to trigger new transmission channels increasing the electric conductivity of the device.

New Self-Organizing Optical Materials and Induced Polymorphic Phases of Their Mixtures Targeted for Energy Investigations.

Herein, a new homologues series of fluorinated liquid crystal compounds, In, 4-(((4-fluorophenyl)imino)methyl)-2-methoxyphenyl 4-alkoxybenzoate were synthesized and its mesomorphic properties were investigated both experimentally and theoretically. The synthesized compounds were characterized by elemental analyzer, NMR, and FT-IR spectroscopy to deduce the molecular structures. The differential scanning calorimetry was employed to examine mesophase transitions whereas the polarized optical microscopy was used to identify the mesophases. The obtained results revealed that the purely nematic phase observed in all terminal side chains. All homologues showed to possess monotropic nematic mesophases except the derivative I8 exhibits enantiotropic property. The optimized geometrical structures of the present designed groups have been derived theoretically. The experimental data was explained using density functional theory computations. The estimated values of dipole moment, polarizability, thermal energy, and molecule electrostatic potential demonstrated that the mesophase stability and type could be illustrated. Binary phase diagram was constructed and addressed in terms of the mesomorphic temperature range and obtained polymorphic phases. It was found that incorporation of the terminal F-atom and lateral CH3O group influence both conformation and steric effect in pure and mixed states. The absorption and fluorescence emission spectra of fabricated films were recorded to elucidate the impact of terminal side chain on photophysical properties of synthesized liquid crystal. It was noted that the increase of terminal side chain length lead to reduction of optical band gap, whereas charge carrier lifetime increases.

Atomistic tight-binding investigations of Mn-doped ZnSe nanocrystal: Electronic, optical and magnetic characteristics

Using the atomistic tight-binding theory with sp-d exchange interaction, the electronic, optical and magnetic properties of Mn-doped ZnSe nanocrystals as a function of magnetic fields and diameters are attained. The magnetic field splits the spin-degenerate states because of the sp-d exchange interaction. The minor reduction of optical band gaps is realized with the increasing magnetic fields. The optical band gaps are significantly decreased with the increasing diameters due to the quantum confinement effect. With the increasing magnetic fields, Zeeman splittings are improved but g-factor values are reduced. The g-factor values are promoted with the increasing diameters. The calculated Zeeman splitting and exciton g-factor value reveal a good agreement with the experimental records. The magnetic field divides the optical spectra into two σ+ and σ− circularly polarized components. Overall, this study will assist the fundamental understanding of the magnetically-doped semiconductor nanocrystals which is valuable for spintronic applications.

Hierarchical porous spinel nickel cobaltite nanoflakes anchored reduced graphene oxide nano-photocatalyst for efficient degradation of organic pollutants under natural sunlight

Hierarchical spinel NiCo 2 O 4 anchored with reduced graphene oxide (NiCO 2 O 4 -rGO) nanoflake composites was prepared by using a chemical route for a high-performance photocatalyst. X-ray diffractometry, field emission scanning electron microscopy and Fourier transform infrared spectroscopy were employed to study the structure, morphology and functional groups of the as-prepared NiCO 2 O 4 -rGO nanoflake composites. The UV–vis diffusive reflectance spectroscopy revealed the reduction of optical bandgap from 1.32 to 1.20 eV compared with pristine spinel NiCo 2 O 4 nanoflakes. NiCO 2 O 4 -rGO nanoflake composites exhibited improved photocatalytic efficiency when compared with that of pristine NiCo 2 O 4 nanoflakes. We verified that 100% degradation of MB in 40 min was observed under natural sunlight irradiation. The photocatalytic degradation efficiency was found to retain 97% of its original value after 6 cycles. The superior photocatalytic efficiency of NiCO 2 O 4 -rGO nanoflake composites over pristine NiCo 2 O 4 nanoflakes is attributed to not only its enhanced surface area providing more active sites for light adsorption but also a heterojunction created between rGO and NiCo 2 O 4 . Addition of rGO greatly improves charge separation efficiency hence decreasing electron hole pair recombination. Overall, this work revealed that synthesis of NiCo 2 O 4 -rGO nanoflake composites may be a promising candidate for the removal of inorganic pollutant from waste water at industrial level under natural sunlight irradiation.

Optical band gap tailoring of muscovite mica via monolayer modification by ultra-low energy ion beam sputtering

In this paper, we report the band gap tailoring of naturally available muscovite mica by ultra-low energy (300 eV) Ar+ ion sputtering at normal ion incidence. The muscovite mica is an insulating material (wide band gap ~ 6 eV) having various potential applications from biological substrate deposition to electronic device fabrication. The first monolayer of mica is modified by ultra-low energy ion beam, which leads to the reduction of optical band gap. The ion dose is varied to study the optical band gap information. It is observed that the band gap decreases significantly with increasing ion doses. By varying ion doses, the indirect band gap could be tailored from 2 eV to 1.1 eV, which indicates the semiconducting nature of mica surface. The optical responses of pristine and modified mica are studied by UV–Visible Spectrophotometry and the band gap is calculated from Tauc's plot. The band gap narrowing is supported by the band gap estimation of modified mica from Conductive Atomic Force Microscopy (C-AFM) analysis. The X-ray photoelectron spectroscopy (XPS) study shows that ion bombardment sputters most of the K atoms and other elements in mica along with Carbon adsorption, which leads to change the density of states of mica, resulting in the tailoring of band gap. The surface morphology study of ion modified mica surfaces, investigated by Atomic Force Microscopy (AFM), shows the formation of random rough surface, which transform to irregular pillar like structure at longer time of ion irradiation.

Optical, electrical, and catalytic (photo-and sono-) properties of indium doped γ-Bi2O3 with Sillenite structure

The exotic structure and properties exhibited by the metastable solids are exemplified adequately in the materials chemistry area. In this report, metastable γ-Bi2O3 has been stabilized without adding any impurity by the auto-combustion method and compared with the changes in structure and optical property brought out by the inclusion of In3+ ions. Compositions doped with indium (7 and 10 mol% in place of bismuth) resulted in stoichiometric Sillenite-type structures as revealed by their powder X-ray diffraction patterns, FTIR, and Raman spectral measurements. The pale yellow γ-Bi2O3 acquired pale brown coloration on indium inclusion, and the intensities varied with varying indium content. Optical bandgap reduction from 2.63 (pure γ-Bi2O3) to 2.41 eV occurred when 10 mol% of indium was doped in place of bismuth. The formation of non-stoichiometric Sillenite structures was noticed in samples with higher indium concentrations (up to 50 mol%). The non-stoichiometric samples displayed intense brown color and showed a drastic reduction in the optical bandgap, reaching values as low as 1.57 eV (50 mol% indium doped sample). From XPS analysis and red-ox titrations, nearly 5% of oxygen excess was estimated for the non-stoichiometric samples doped with indium. The BET surface area of indium doped non-stoichiometric Sillenites (126 m2/g) was higher than indium doped stoichiometric Sillenites (74 m2/g). The oxygen ion conductivity studies of pure γ-Bi2O3 and indium doped non-stoichiometric Sillenites revealed a marginal rise in conductivity with indium inclusion.

α-Fe2O3/ZnO heterostructure for enhanced photocatalytic and antibacterial activity

This paper reports the accomplishment of a noticeable enhancement in the photodegradation and antibacterial activity of α-Fe2O3 by a heterostructure formation between α-Fe2O3 and ZnO flakes. The heterostructure yields 97% photodegradation of methylene blue pollutant in water within 180 min, which is a fourfold increase compared to that observed with a pure α-Fe2O3 nanostructure. Further characterisations indicate that the improved results are attributable to the reduction in optical band gap, the increased electrical conductivity, the improved spatial separation of carriers and the enhanced amount of available hydroxyl radicals for the reaction. The stability and reusability of the photocatalysts are confirmed for four consecutive cycles of operations. The phase identification and structural studies are done using x-ray diffraction, transmission electron microscopy and x-ray photoelectron spectroscopy in conjunction with surface morphology from field emission scanning electron microscopy. The enhancement of room temperature electrical conductivity by five times and band gap reduction from 1.98 eV to 1.75 eV for the heterostructures, when compared with α-Fe2O3 nanostructures, are obtained from voltage–current measurements and optical reflectance spectra.