Search

In this study, a sustainable visible light promoted photocatalytic route has been developed for mineralization of alachlor pesticide using CuS/BiFeO 3 heterojunction materials. The heterojunctions were synthesized by a two-step process and characterized using XRD, FESEM, HRTEM, XPS, FTIR, UV–Vis-DRS and PL techniques. Morphologically, the heterojunction materials consist of BiFeO 3 nanoplates with high aspect ratio and CuS nanorods. The intimate contact between the two phases was ascertained from the HRTEM study. Optical property study suggested that these materials show excellent absorption in visible region with superior charge carrier separation characteristics compared to the individual components. The transient photocurrent measurement and I-V plots revealed high mobility of the excitons across grain boundary due to heterojunction formation. The band positions of the two components were aligned favourably for a cyclic movement of electrons and holes resulting in a type-II heterojunctions. The CuS/BiFeO 3 materials efficiently catalyse the mineralization of alachlor pesticide under visible light illumination achieving >95% degradation within 60 min. The mechanism of alachlor degradation over the catalyst surface was elucidated using GCMS and radical scavenger experiments. The attractive features of the developed photocatalytic method are the use of renewable energy, low cost, high efficiency, stability and recyclability of the catalyst material. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zr-pillared α-ZrP was prepared by insertion of Zr-oxyhydroxy nanoclusters into the interlayer region. • The Zr-pillared α-ZrP is used as a carrier for dispersion of catalytically active Cs x H 3-x PW 12 O 40 species. • The composite catalytic system exhibits enhanced gallery height, high surface area, porosity and surface acidic properties. • Well dispersed Cs x H 3-x PW 12 O 40 nanoparticles with size 8–15 nm. • The composite catalytic system is highly active for synthesis of spirooxindoles by multicomponent condensation approach. Layered α-zirconium phosphate (α-ZrP) was prepared by reflux method using ZrOCl 2. 8H 2 O and H 3 PO 4 as precursor. The α-ZrP material was pillared with Zr-oxyhydroxy nanoclusters to prepare Zr-pillared α-zirconium phosphate (ZZP). An enhancement in interlayer spacing, surface area and porosity was noticed as a result of Zr-pillaring. The cesium exchanged phosphotungstic acid (Cs x H 3-x PW 12 O 40) nanoparticles were dispersed in the porous matrix of ZZP material to prepare Cs x H 3-x PW 12 O 40 -ZZP nanocomposite systems. The nanocomposites were characterized using XRD, FTIR, UV–vis-DRS, TGA-DTA, XPS, N 2 sorption, TPD, FESEM and HRTEM techniques. The expansion in layer structure of α-ZrP upon pillaring and its subsequent retention in the composite material was noticed from XRD. UV–vis and FTIR study indicated structural integrity of the Cs x H 3-x PW 12 O 40 nanoclusters in the ZZP interlayer. The surface area of the composite materials was in the range of 80–130 m2 g−1. The composite materials contained significantly higher amount of medium and strong acidic sites compared to the ZP and ZZP materials. Microscopic study suggested the presence of hierarchical nanospheres with diameter between 150 and 200 nm. The presence of well dispersed Cs x H 3-x PW 12 O 40 nanoparticles with size between 8 and 15 nm was confirmed from HRTEM study. The nanocomposite materials were used as efficient heterogeneous catalyst for synthesis of spirooxindoles by multicomponent one pot condensation of isatin, malononitrile, naphthol/1,3-diketones. Structurally diverse spirooxindole derivatives were synthesized in high yield and purity in short span of time using the Cs x H 3-x PW 12 O 40 -ZZP nanocomposites as catalyst under mild conditions. [ABSTRACT FROM AUTHOR]

A series of α-Fe 2 O 3 -Bi 2 S 3 heterojunction materials were prepared by a one-step autocombustion method employing thiourea as fuel. The heterojunction materials were characterized using XRD, UV–Vis-DRS, FTIR, PL, XPS, FESEM, TEM and HRTEM analytical techniques. XRD study indicated presence of rhombohedral α-Fe 2 O 3 and orthorhombic Bi 2 S 3 in the heterojunction materials. The heterojunctions displayed better optical absorption in the visible region and enhanced charge carrier separation characteristics. The oxidation state of the constituent elements on the surface was established from XPS study. IR study showed the characteristic vibrational features of both α-Fe 2 O 3 and Bi 2 S 3 phases. Microscopic studies indicated presence of well dispersed α-Fe 2 O 3 nanorods in a continuous Bi 2 S 3 matrix. The α-Fe 2 O 3 nanorods were typically 30–50 nm in diameter and 120–150 nm in length growing isotopically in different direction from a single nucleation point. The calculated band positions of both components indicated a facile electrons transfer from the conduction band of α-Fe 2 O 3 to Bi 2 S 3 whereas migration of holes occurs in the reverse direction yielding a type-II heterojunction. The α-Fe 2 O 3 -Bi 2 S 3 heterojunctions materials were evaluated as selective and efficient photocatalyst for the hydrogen transfer reduction of nitroarenes under visible light illumination. Structurally diverse nitroarenes could be selectively reduced to the corresponding amines in high yield and purity using α-Fe 2 O 3 -Bi 2 S 3 as photocatalyst. [ABSTRACT FROM AUTHOR]

Highlights: [•] Polyphosphoric acid–Zr-pillared clay composites prepared by different strategies. [•] Expansion of clay interlayer on intercalation of PPA and Zr-polycations. [•] Structural integrity of PPA confirmed from EDX, FTIR, UV–vis studies. [•] PPA–ZrP composite is highly active for the synthesis of tetrahydropyridines. [•] Structurally diverse tetrahydropyridines synthesized under mild condition. [Copyright &y& Elsevier]

Highlight: [•] Iron oxide–alumina nanocomposite fibers were prepared by electrospinning method. [•] Pure crystalline ultra-fine fibers were obtained after sintering at 1000°C. [•] The nanocomposite fibers are efficient adsorbent for removal of heavy metal ions. [•] The removal percentage was in the order of Cu2+

Polycrystalline nano BiFeO3 powders were synthesized by auto-combustion method using urea as fuel and metal nitrates (Fe(NO3)3·9H2O, Bi(NO3)3·5H2O) as oxidizers. In order to optimize the single-phase synthesis condition of BiFeO3, different fuel to oxidizer ratios have been investigated. The preliminary structural investigation using X-ray diffraction shows the samples were of single phase and crystallize in rhombohedral structure (R3c). The ferroelectric and antiferromagnetic ordering temperatures of BiFeO3 were found to be 832 °C and 364 °C respectively, from differential thermal analysis. The temperature dependent dielectric study shows an anomaly around 215 °C which corresponds to magneto-electric coupling in the material. Field-emission scanning electron micrographs show effect of fuel to oxidizer ratio on grain size evolution. The ferroelectric hysteresis loops for all the samples were measured at a frequency of 100 Hz confirming the ferroelectric nature. An evidence of magneto-electric coupling was also observed at room temperature from magneto-capacitance measurements. [ABSTRACT FROM AUTHOR]

Abstract: Nanocomposites composed of mixed iron and aluminium oxide (Fe2O3–Al2O3), have been synthesized by hydrothermal method, and further used as adsorbent for the adsorptive decolorization of Congo red dye from an aqueous system. The as-prepared nanomaterials were sintered at 500°C and 1000°C, to obtain pure Fe2O3–Al2O3 mixed composites. The XRD studies confirmed the formation of pure and crystalline FeOOH–AlOOH (as-prepared), γ-Fe2O3–Al2O3 at 500°C and α-Fe2O3–Al2O3 phases at 1000°C. The morphology and size of the obtained nanocomposites were characterized by SEM and TEM. Effects of pH, contact time, initial concentration of adsorbate have been studied. The optimum pH for maximum removal of Congo red in all the three phases of nanocomposites was found to be 7. The maximum removal capacity was 498mg/g for γ-Fe2O3–Al2O3 phases. Among the three different adsorbents, γ-Fe2O3–Al2O3 shows complete removal within 15min of contact time. [Copyright &y& Elsevier]

Highlights: [•] Cr-P clay served as efficient support for dispersion of silicotungstic acid. [•] IR and UV–Vis study illustrates the structural integrity of the STA particles. [•] The interlayer spacing of Cr-P was retained after incorporation of STA particles. [•] The particle size of the supported STA is in the range of 15–25nm. [•] The STA/Cr-P material highly efficient catalyst for synthesis of 1,4-dihydropyridines. [Copyright &y& Elsevier]

Abstract: A series of MoO3–ZrO2 nanocomposite oxides with MoO3 content in the range of 2–20mol% were prepared by solution combustion method. Three different fuels namely urea, glycine and hexamethylenetetramine (HMTA) were used for the preparation of MoO3–ZrO2 oxides. For the sake of comparison, the MoO3–ZrO2 composite oxides were also prepared by impregnation of zirconia with molybdenum salt precursor and subsequent heat treatment. The synthesized nanomaterials were characterized by XRD, SEM, TEM and UV–vis spectroscopic technique. XRD study indicated selective stabilization of the tetragonal phase of zirconia in the presence of MoO3. The method of preparation was found to be crucial for the phase composition of zirconia in the composite oxide. The crystallite size and rms stain were calculated from the Fourier line shape analysis of the broadened X-ray diffraction profiles. With increase in the MoO3 content, the crystallite size of the tetragonal zirconia phase was found to be decreased. TEM study indicated the presence of small nanoparticles with size in the 5–10nm range. UV–vis study of the composite oxide materials revealed well dispersion of the molybdenum oxide component in the form of monomer, dimers and nanoclusters in the zirconia matrix. The nature of fuel was found to be crucial in determining the morphology and shape of the particles. [Copyright &y& Elsevier]

Abstract: Ultra-fine Al2O3 fibers were synthesized via electrospinning technique using PVP/ethanol polymer solution and aluminium acetate sol followed by calcinations at higher temperature. The formation, crystalline phase, surface morphology, fibers diameter and surface area of alumina ultra-fine fibers were characterized using FT-IR, TGA/DTA, XRD, SEM, TEM and BET analytical techniques. The results show that pure and crystalline α-Al2O3 ultra-fine fibers were formed with fiber diameter in the range of 100–500nm and BET surface area of the fibers were found to be 40m2/g. [Copyright &y& Elsevier]

Abstract: Pure ZrO2 and MoO3 (10mol%)-ZrO2 nanocomposite oxides were prepared by solution combustion method using glycine as fuel. The synthesized materials were characterized by X-ray diffraction (XRD), Scanning Electron microscopy (SEM), Transmission electron microscopy (TEM) and UV–vis spectroscopic technique. XRD study revealed selective stabilization of the tetragonal phase of zirconia in presence of MoO3. The crystallite size was calculated from the Fourier line shape analysis of the broadened X-ray diffraction profiles as well as from TEM measurements. Oxide nanoparticles with size in the range of 5–40nm was observed depending upon the fuel content in the combustion mixture. UV–vis study indicated well dispersion of the molybdenum oxide component in the zirconia matrix in the form of isolated and cluster molybdates. The MoO3–ZrO2 nanocomposite oxide was used as an efficient and environmentally benign catalyst for the synthesis of octahydroquinazolinones by multicomponent condensation reaction of dimedone, urea and arylaldehydes in aqueous media as well as under solvent free condition using microwave irradiation. A series of zirconia based heterogeneous catalyst with different acidity and surface area were screened for this reaction. The MoO3 (10mol%)-ZrO2 catalyst was found to be highly active for the transformation with excellent yield and purity of the product in a short reaction time. [Copyright &y& Elsevier]

Abstract: Natural kaolin was refluxed with sulphuric acid of different concentrations 1M, 3M, 5M and 10M at 110°C for 4h followed by calcination at 500°C for 2h. The physico-chemical characteristics of acid-leached kaolinite clay were studied by XRF, XRD, FTIR, TGA, DTA, SEM and N2 adsorption techniques. XRF and FTIR studies indicate that acid treatment under reflux conditions leads to the removal of the octahedral Al3+ cations along with other impurities. XRD of 5M and 10M treated kaolin shows that treatment with high concentrated acid provoked an amorphization resulting in the formation of an amorphous silica type phase. Leaching of Al3+ ions increased progressively with severity of the acid treatment. The acid treatment increased the Si/Al ratio from 0.65 to 8.09, surface area from 23m2/g to 143m2/g and pore volume from 0.361cc/g to 1.18cc/g as the acid concentration was increased to 10M. Solids thus obtained by acid treatments can be used as promising adsorbents and catalyst supports. [Copyright &y& Elsevier]

[Display omitted] Rational design of novel conjugated step-scheme (S-scheme) multijunction heterostructure with synergistic charge channelization, superior light harvesting efficiency and strong redox ability is a pioneering approach to mimic natural photosynthesis process. Herein, a mild cetyltrimethyl ammoniumbromide (CTAB) assisted one pot reflux synthesis route is designed for in situ integration of metal organic framework (MOF)-derived NiFe 2 O 4 with tetragonal-BiVO 4 (t-BiVO 4) and γ-Bi 2 MoO 6 to prepare NiFe 2 O 4 /t-BiVO 4 /Bi 2 MoO 6 (NFO/BVO/BMO) ternary composites. Morphologically, fine dispersion of NiFe 2 O 4 (NFO) quantum dots over γ-Bi 2 MoO 6 (BMO) and t-BiVO 4 (BVO) nanoplates yielded three types of microscopic heterojunctions among BMO-BVO, BVO-NFO and BMO-NFO phases. The ternary composites displayed important physicochemical attributes including high surface area, strong optical absorption, superior charge mobility and higher excited state lifetime which accounted for its improved photocatalytic activity towards ciprofloxacin degradation (>99% in 90 min) and H 2 evolution (1.11 mmolh-1g−1, photon conversion efficiency 18.5%). Kinetics study revealed 12–55 fold higher ciprofloxacin photodegradation activity and 31–41 times higher H 2 evolution rate for the ternary composite in comparison to the pure semiconductors. A conjugated S-scheme charge transfer mechanism has been deduced from comprehensive band position analysis and radical trapping study to explain the enhanced photocatalytic activity. This work for the first time demonstrated the rational construction of conjugated S-scheme heterostructures with potential application in water remediation and green H 2 production. [ABSTRACT FROM AUTHOR]

A series of CaO–ZrO 2 nanocomposite oxides containing 2–50 mol% of CaO were synthesized employing urea as a mild hydrolyzing agent. The nanocomposite systems were characterized using XRD, Fourier analysis, TPD, Raman, XPS, TGA-DSC, FESEM, HRTEM, and BET surface area measurement techniques. XRD study indicated selective stabilization of the tetragonal zirconia phase in the composite oxide. Upto 20 mol% CaO, the Ca 2+ ions substituted for Zr 4+ ions in the zirconia lattice to form a substitutional solid solution. Beyond 20 mol% CaO, the presence of a mixed phase system consisting of the solid solution phase, CaO and nonstoichiometric Zr 0.93 O 2 phase was observed. The composite oxides contain crystallites with size <20 nm as observed from Fourier and HRTEM analysis. TPD study revealed a significant enhancement in the basicity of zirconia as a result of Ca 2+ incorporation. XPS study confirmed presence of different lattice oxygen as potential basic sites. Raman spectral data indicated the presence of oxygen vacancy and distortion in oxygen sublattice due to Ca 2+ incorporation to zirconia. Microscopic investigation of the composite oxide suggested a gradual morphological change from rod shape particles to flake like and subsequently to cubic morphology with increase in CaO content in the composite. The CaO–ZrO 2 nanocomposite oxides were used as an efficient and recyclable heterogeneous base catalyst for synthesis of chromene analogues. Structurally diverse 2-amino-4H-chromenes and 2-amino-2-chromenes were synthesized in high yield and purity under mild condition using CaO-ZrO 2 material as catalyst and multicomponent condensation approach. [ABSTRACT FROM AUTHOR]

MgO nanorods, hierarchical nanostructures and nanoflakes were synthesized by precipitation, reflux and hydrothermal methods, respectively. The SEM and FESEM images suggested the formation of nanorods with diameter around 400–500 nm, hierarchical nanostructures containing plates with thickness around 100–200 nm and nanoflakes with diameter around 300–500 nm. XRD and FTIR confirmed the formation of single phase MgO with well crystalline nature. The hierarchical MgO nanostructures possessed higher specific surface area (147.5 m 2 /g) than MgO nanorods (48.45 m 2 /g) and nanoflakes (110.9 m 2 /g). The prepared nanomaterials were used as adsorbents to remove organic dyes such as Malachite green and Congo red from aqueous media. The percentage of removal of Malachite green by MgO nanorods, hierarchical nanostructures and nanoflakes are 95.1, 99.98 and 97.42%, respectively, and percentage of removal of Congo red by MgO nanorods, hierarchical nanostructures and nanoflakes are 86.28, 99.94 and 92.68%, respectively. The hierarchical MgO nanostructure exhibited excellent adsorption performance for removal of Malachite green and Congo red with maximum sorption capacities of 1205.23 and 1050.81 mg/g, respectively. [ABSTRACT FROM AUTHOR]

Abstract: A series of MoO3–ZrO2 composite oxide catalysts were prepared by coprecipitation and impregnation methods and characterized by XRD, Raman, UV–Vis, TEM and sorptometric techniques. Characterization studies indicated the presence of tetragonal zirconia phase and well dispersed MoO3 species as isolated and polymolybdate clusters in the composite oxide. The MoO3(20mol%)–ZrO2 material was used as efficient catalyst for synthesis of amidoalkyl naphthols under solvent free conditions using conventional as well as microwave heating. The results obtained clearly showed that the composite oxide catalyst was recyclable and highly efficient for the reaction giving good yield and purity of the products. [Copyright &y& Elsevier]

[Display omitted] • A novel multi-junction BSxBWO heterostructure is fabricated by in-situ co-assembly technique. • The partial doping of Bi5+ into (W 2 O 7)2- bilayers leads to formation of atomic oxygen vacancy. • The oxygen defects favor rapid electron channelization and enhance space charge separation. • The BS15BWO photocatalyst shows improved MP mineralization (0.013 min−1) and H 2 production (0.92 mmolg-1h−1) activity. • A type-I conjugated dual S-scheme charge migration mechanism accounts for its robust activity. In this study, a facile in situ co-assembly technique is developed for one pot fabrication of Bi 2 S 3 /SnS 2 /Bi 2 W 2 O 9 multijunction photocatalyst. Initially, Aurivillius phase Bi 2 W 2 O 9 with nanoplate morphology is prepared by combustion synthesis route. The hydrothermal co-deposition of SnS 2 and Bi 2 S 3 phase led to the formation of the ternary composite photocatalyst. During hydrothermal treatment, substantial microstructural reorganization of the BWO phase occurred resulting in exfoliation of the nanoplates to high aspect ratio nanosheets followed by substitution of Bi5+ ions in the [W 2 O 7 ]2- bilayer of the BWO structure. The Bi-self doping phenomena also resulted in creation of oxygen vacancy in the BWO lattice. Morphological investigations revealed intimate interfacial contact among hexagonal SnS 2 nanoplates, Bi 2 S 3 nanorods and Bi-doped Bi 2 W 2 O 9 nanosheets. The oxygen vacancy (OV) and Bi self-doping endow improved photoelectrochemical properties and enhanced photocatalytic activity towards methyl parathion photodegradation (k app = 0.013 min−1) and hydrogen evolution (0.92 mmolg-1h−1). The optimal BS15BWO photocatalyst exhibited nearly 13 and 32 times higher photocatalytic activity for methyl parathion photodegradation and H 2 evolution reaction in comparison to the pure components. The robust generation of •OH and •O 2 − radicals and improved charge channelization through a type-I conjugated dual S-scheme electron migration mechanism accounted for the improved photocatalytic activity of the ternary composite. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The CuS/Bi 4 Ti 3 O 12 p-n heterojunction material were synthesized. • Flower like hierarchical structures with improved visible light absorption. • Intra-electric field and microscopic contact are vital for photocatalytic activity. • CuS/Bi 4 Ti 3 O 12 materials highly active for MCPA degradation under visible light. • The mechanistic details of MCPA degradation is illustrated. Abstract In this study, a series of CuS/Bi 4 Ti 3 O 12 p-n heterojunction materials were synthesized by a two-step process. Initially, the Aurivillius phase Bi 4 Ti 3 O 12 (BT) was synthesized by a facile combustion route using urea as a fuel. The Bi 4 Ti 3 O 12 was subsequently modified by deposition of CuS (5–20 wt%) using a hydrothermal route to prepare the heterojunction materials. The methods of synthesis and calcination temperature were important factors which influenced the morphology, particle size and phase purity of Bi 4 Ti 3 O 12 material. Phase pure BT nanoplates with planar dimension of 150–200 nm and thickness between 50 and 70 nm were obtained at a calcination temperature of 600 °C. Pure CuS prepared by hydrothermal method, contained hierarchical microspheres with diameter in the range of 1.2–1.6 μm. The heterostructure materials exhibited hierarchical flower like structure consisting of ultrathin CuS nanosheets and BT-nanoflakes. HRTEM and microstructural study revealed microscopic close interaction between the two phases. The optical and electrical measurement study suggested significant improvement in visible light absorption (400–800 nm) and charge carrier separation due to heterojunction formation. The CuS/Bi 4 Ti 3 O 12 materials showed excellent photocatalytic activity for aqueous phase degradation of 2-methyl-4-chlorophenoxyacetic acid (MCPA) herbicide under visible light (>95% degradation in 3 h). The rate constant for CuS/Bi 4 Ti 3 O 12 materials was 4.5 times higher than the pure BT material towards MCPA degradation. The OH and O 2 – radicals have been identified as the reactive species, the formation of which was confirmed by spectrometric method using terephthalic acid and nitroblue tetrazolium as molecular probes. The mechanism of MCPA degradation over the photocatalyst surface has also been elucidated using LC-ESI-MS, TOC and scavenger experiments. [ABSTRACT FROM AUTHOR]

In this study, Bi 2 O 2 CO 3 (BSC) nanoplates with high aspect ratio and hierarchical nanostructures were prepared by hydrothermal technique using urea/hexamethylenetetramine as hydrolysing agent and KCl as additive in different solvent systems. The relative molar proportion of urea and KCl was crucial for phase purity as well as thickness and planar dimension of the BSC plates. The BSC nanoplates were used as substrates to prepare CuS-Bi 2 O 2 CO 3 (CuS/BSC) direct z-scheme heterojunction systems. The heterojunction materials were characterized by FESEM, HRTEM, XRD, PL, FTIR and UV–Vis-DRS techniques. The presence of crystalline tetragonal BSC and hexagonal covellite CuS phase was inferred from XRD study. Morphologically, the CuS/BSC material contained CuS nanorods and BSC nanoplates. HRTEM study suggested microscopic close contact between the CuS nanorods and BSC nanoplates. Optical property study revealed improvement in visible light absorption and enhanced separation of excitons. The CuS/BSC materials were used as photocatalyst for chlorpyrifos pesticide degradation under visible light irradiation. The heterojunction materials were highly active achieving >95% degradation within 3 h of reaction. The pathway and mechanism of CP degradation was elucidated using GCMS and radical scavenger experiments. [ABSTRACT FROM AUTHOR]

In this study, an efficient photocatalytic route is developed for degradation of carbendazim fungicide under visible light irradiation using Bi 2 S 3 /BiFeO 3 heterojunction materials as photocatalyst. The heterojunction system prepared by a two-step process contains rhombohedral BiFeO 3 and orthorhombic Bi 2 S 3 as crystalline phases. Morphologically, the Bi 2 S 3 /BiFeO 3 materials contain BiFeO 3 nanoplates and Bi 2 S 3 nanorods in close microscopic contact. The Bi 2 S 3 /BiFeO 3 materials exhibited improved visible light absorption, enhanced charge carrier separation and efficient photocatalytic activity achieving 96% degradation within 2 h of reaction. The mechanistic pathway for carbendazim degradation has been elucidated using GC-Mass analysis and radical scavenger experiments. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel hierarchical UN/CDS/CAS hybrid material is prepared by a low temperature reflux route. • The heterostructure exhibited sulfur vacancy and strong interfacial contact. • Photo-electrochemical analysis confirmed fast channelization of photo-excited charge carriers. • The hybrid material displayed superior ASM degradation (0.02 min−1) and H 2 evolution (493-1 µmol g-1h−1) activity. • A dual S-scheme charge migration mechanism accounted for the improved activity. The in-situ fabrication of dual S-scheme ternary heterostructure is a promising approach to isolate photo-induced electron-hole and boost the efficiency of a semiconductor photocatalyst. However, the dual S-scheme heterostructure based on MOFs are rarely narrated. Herein, a S-vacancy rich hierarchical UiO-66(–NH 2)/CdIn 2 S 4 /CaIn 2 S 4 ternary hybrid material is successfully fabricated by in-situ preferential growth of ultrathin CaIn 2 S 4 nanosheets and CdIn 2 S 4 nanorods in presence of UiO-66(–NH 2) (UN) spherical nanoparticles by using a simple reflux route. The physiochemical characteristics and optoelectronic features of the developed materials are illustrated in detail. The efficacy of UiO-66(–NH 2)/CdIn 2 S 4 /CaIn 2 S 4 ternary hybrid material is explored for photocatalytic H 2 evolution reaction and decontamination of asulam (ASM) herbicide. The development of S-vacancy facilitates interfacial charge carrier migration and reduces the recombination rate. The enhanced photocatalytic H 2 production and ASM degradation could be ascribed to staggered band alignment between UiO-66(–NH 2) (UN), CdIn 2 S 4 (CDS) and CaIn 2 S 4 (CAS), which support S-scheme charge channelization in the heterojunction. Due to its physio-chemical advantages, the optimal 15UN/CDS/CAS30 hybrid photocatalyst exhibits highest photocatalytic H 2 evolution rate of 4931 μmol g−1h−1 with apparent conversion efficiency of 31.5% and ASM degradation > 93% (k = 0.02 min−1) under irradiation of visible light. This work furnishes a new perceptive into the in-situ construction of dual S-scheme photocatalytic systems for renewable energy production and decontamination of organic pollutants. In addition, this study for the first time illustrates mineralization of Asulam using a heterogeneous photocatalytic route. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bi- self doped Bi 2 MoO 6 with nanoplate morphology prepared by reflux route. • Bi self-doping induces part reduction of Mo6+ to Mo5+ and creation of Mo vacancy. • CaFe 2 O 4 /Bi 2 MoO 6 0D-2D p-n heterojunction fabricated by integrating CaFe 2 O 4 QDs. • Improved activity for bisphenol A (k app = 0.0132 min−1) degradation and Cr(VI) (k app = 0.15 min−1) reduction. • Reaction rates for p-n heterojunction 5–9 times higher than pure semiconductors. In this study, a mild reflux route was developed for facile synthesis of Bi-self doped Bi 2 MoO 6 (BMOR) with nanoplate morphology. Microstructural study revealed substitution of Bi5+ ions in the molybdate layer which resulted in partial reduction of Mo6+ to Mo5+ ions and creation of Mo vacancy. The defect engineered BMOR material exhibited improved optical and photoelectrochemical properties compared to its undoped analogue. The BMOR material was subsequently employed as host lattice for construction of CaFe 2 O 4 /Bi 2 MoO 6 0D-2D p-n heterojunctions by using an in situ preparative strategy. Well dispersed CaFe 2 O 4 quantum dots over BMOR nanoplates provide a strong interfacial contact conducive for fast charge mobilization. Comprehensive characterization of the composites revealed extended UV–vis response, improved charge carrier separation, prolonged excited state life time and robust radical generation efficiency compared to pure components. The CaFe 2 O 4 /Bi 2 MoO 6 composites displayed improved photocatalytic performance for bisphenol A (BPA) degradation (k app = 0.0132 min−1) and Cr(VI) reduction (k app = 0.15 min−1) with reaction rates 5–9 times higher than pure components. The involvement of •OH and •O 2 − radicals in the photodegradation of BPA was confirmed from radical trapping study. The formation of an interfacial p-n heterojunction and a double charge migration mechanism accounted for the improved photocatalytic efficacy of the composite. [ABSTRACT FROM AUTHOR]

Design of biocompatible nano-heterostructure photocatalyst with broad UV–visible spectrum response and strong redox ability is a promising approach with potential application in micropollutant degradation and pathogen deactivation from aqueous sources. Herein, we have reported the facile fabrication of In 2 S 3 /Bi 2 Fe 4 O 9 (ISxBFO) binary heterostructure by hydrothermally depositing In 2 S 3 nanoparticles (20–40 nm) over Bi 2 Fe 4 O 9 nanocuboids/nanoplates prepared by combustion synthesis route. In depth characterization study revealed broad spectrum UV–Vis absorption, large interfacial contact, improved charge carrier separation and mobility and a longer excited state life time (4.7 ns) for the ISxBFO heterostructure materials. The integration of In 2 S 3 with Bi 2 Fe 4 O 9 strongly boosts the optoelectrical and photocatalytic property of pristine Bi 2 Fe 4 O 9. The ISxBFO heterostructure material exhibited enhanced photocatalytic efficiency for aqueous phase degradation of sulfamethoxazole antibiotics (k app = 0.06 min−1) and phenyl urea herbicides (k app = 0.028 min−1) with reaction rates 3–8 times higher than the pure BFO component. The MTT assay experiments confirmed non-cytotoxic nature of treated sulfamethoxazole and diuron solutions. The composite materials also displayed convincing antibacterial behavior towards toxigenic Vibrio cholerae pathogen. Haemagglutination assay study revealed excellent biocompatibility of the binary composite up to 200 mg L−1. Radical trapping study suggested expeditious generation of •OH and •O 2 − radicals over the ISxBFO surface which is nearly 3.8 and 2.3 times higher than pure BFO and In 2 S 3 respectively. The occurrence of a direct Z-scheme mechanism is inferred from radical trapping and XPS study which accounted for the improved photocatalytic activity and strong radical generation property of the ISxBFO heterostructure material. [Display omitted] • A broad spectrum visible light active Z-scheme In 2 S 3 /Bi 2 Fe 4 O 9 composite fabricated. • Composite exhibited better photoelectrochemical feature and excited state life time. • Enhanced activity for sulfamethoxazole and phenyl urea herbicide photodegradation. • Convincing photocatalytic antibacterial property for toxigenic Vibrio cholera. • Haemagglutination assay study revealed biocompatible nature of the composite. [ABSTRACT FROM AUTHOR]

A series of sulfonated polyvinyl alcohol-Zr-pillared clay nanocomposites were synthesized. A low molecular weight polyvinyl alcohol (PVA) was sulfonated using chlorosulfonic acid. The sulfonated PVA was intercalated inside the parent clay and Zr-pillared clay (Zr-P) matrix. In an alternative approach, the polyvinyl alcohol was initially intercalated into the clay and Zr-P structure followed by in-situ sulfonation inside the clay matrix. The composite materials were characterized using XRD, FTIR, Raman, UV–vis and FE-SEM analytical techniques. Expansion in clay interlayer due to insertion of the polymeric species and the Zr-pillars was observed from XRD study. FTIR and UV–vis study revealed presence of hydrated sulfonic acid clusters in the composite materials. The clay sheets were largely present in an exfoliated state in the clay-polymer composite materials. Insertion of the Zr-pillar imparts structural rigidity and consequent changes in the morphological features. The catalytic activity of the Zr-pillared clay-sulfonated polyvinyl alcohol composite materials has been investigated for synthesis of hexahydropyrimidines by multicomponent condensation of substituted aniline, formaldehyde and β-dicarbonyl compounds. The composite materials were found to be highly active for synthesis of structurally diverse hexahydropyrimidines in high yield and purity. [ABSTRACT FROM AUTHOR]

Facile fabrication of visible light responsive multicomponent heterostructure photocatalysts with synergistic photoelectron migration is an effective approach with potential application in water remediation and renewable energy generation. In this study, a series of ternary multi-heterojunction CdS/Bi 20 TiO 32 /Bi 4 Ti 3 O 12 (CdSxBTC) photocatalysts were prepared by hydrothermal deposition of CdS nanoparticles (15–25 nm) over one pot combustion synthesized Bi 20 TiO 32 /Bi 4 Ti 3 O 12 (BTC) nanostructures. Comprehensive characterization of the ternary composites revealed enhanced optical absorption, high interfacial contact, fast electron channelization and a prolonged excited state life time. The CdSxBTC composite materials displayed enhanced photocatalytic activity for endosulfan degradation (k app value 6–12 times greater than pure semiconductors) and water splitting reaction (H 2 production rate 1890 μmolg−1h−1 and apparent conversion efficiency 19%). The cell viability -study disclosed non-cytotoxic nature of the treated endosulfan solution. A synergistic Type-I bridged coupled Z-scheme electron migration process accounted for robust radical generation ability (•O 2 − and •OH) and photocatalytic activity of the ternary composites. [Display omitted] • A simple and rapid combustion route is devised for one step synthesis of Bi 20 TiO 32 /Bi 4 Ti 3 O 12 binary composite. • Hydrothermal deposition of CdS leads to the formation multi-heterojunction CdS/Bi 20 TiO 32 /Bi 4 Ti 3 O 12 ternary composite. • A synergistic Type-I bridged coupled Z-scheme electron migration explains robust generation of reactive oxygen species. • The ternary composites highly active for endosulfan degradation (0.03527 min−1) and H 2 production (1890 µmol g−1 h−1). • Cell viability study substantiates non-cytotoxic nature of the treated endosulfan solution and the photocatalyst. [ABSTRACT FROM AUTHOR]

Abstract: A series of CeO2–CaO nanocomposite oxides were synthesized by the amorphous citrate method and characterized by TGA, XRD, UV–Vis-DRS, SEM and TEM experimental techniques. The XRD analysis indicated the presence of a substitutional type solid solution for ceria rich composite oxides whereas for the calcium oxide rich composite oxides, the presence of crystalline CaO was observed along with the solid solution phase. Fourier line profile analysis of the broadened X-ray diffraction profiles revealed the presence of small nanocrystallites of the mixed oxides with size in the range of 5–25nm. UV–Vis-DRS study of the composite oxide showed well dispersion of the ceria in the CaO matrix. The characteristic reflections from the low coordinated surface Ce4+ ions were observed in the UV study along with a blue shift in the absorption edge for samples containing up to 20mol% ceria. The direct band gaps calculated from the UV spectra were found to be in the range of 3.45–3.66eV. The composite oxide materials were found to be porous and spongy in nature observed from the SEM analysis. TEM study of the CeO2(20%)–CaO material indicated the presence of well dispersed mixed oxide nanoparticles in a continuous CaO matrix. The Ce–Ca–O nanocomposite oxides were used as an environmentally benign catalyst for the multicomponent one pot synthesis of 2-amino-2-chromenes by multicomponent condensation of aryl aldehydes, α-naphthol and malononitrile in aqueous media. The nanocomposite oxides were found to be highly efficient for the synthesis of structurally diverse aminochromenes with excellent yield and purity. [Copyright &y& Elsevier]

Abstract: Nanosized sulfated tin oxide (STO) particles dispersed in the micropores of Al-pillared clay were prepared by a precipitation–deposition method followed by heat treatment and sulfation. The Al-pillared clays (Al-P) was prepared by the intercalation of [Al13O4(OH)24(H2O)12]7+ clusters into the clay interlayers. The physicochemical characteristics of the STO/Al-P material were evaluated by using X-ray diffraction (XRD), infrared (IR), transmission electron microscopy (TEM) and sorptometric studies. XRD results indicate an expansion in the interlayer spacing upon pillaring. The layer structure is found to be retained after the dispersion of the STO particles. The TEM images indicate the presence of uniform STO particles with sizes in the 5–15nm range. The sorptometric study show a type I isotherm for both the Al-P and STO/Al-P material, indicating the presence of micropores. The pore volume of the parent-pillared clay was found to decrease upon supporting the STO particles. The STO/Al-P material was used as an environmentally benign, recyclable and efficient catalyst for the solvent-free synthesis of 3,4-dihydropyrimidin-2(1H)-ones, thiochromans, with selective protection of aldehyde groups such as 1,1-diacetates and coumarins. The STO/Al-P catalyst was highly active for the synthesis of the above-mentioned molecules. The protocol developed using this catalyst has many advantages over those of the conventional mineral acids used as catalysts. [Copyright &y& Elsevier]

[Display omitted] • Bi 2 O 3 /CuBi 2 O 4 and CuO/CuBi 2 O 4 materials synthesized by one step combustion method. • Plasmonic Ag nanoparticles photo-deposited over binary Bi 2 O 3 /CuBi 2 O 4 material. • Enhanced photocatalytic activity observed for 17α-ethynylestradiol degradation and Cr(VI) reduction. • Significant increase in photoelectrochemical and charge carrier separation property. • Improved activity is due to step scheme junction and surface Plasmon Ag cocatalyst. In this study, we have developed a facile and less time consuming one pot solution combustion method to prepare Bi 2 O 3 /CuBi 2 O 4 (BO/CBO) and CuO/CuBi 2 O 4 (CO/CBO) heterojunction materials by optimizing the Cu/Bi/urea molar ratio. The as prepared optimal Bi 2 O 3 /CuBi 2 O 4 binary material was further modified by plasmonic Ag nanoparticles to construct Bi 2 O 3 /CuBi 2 O 4 /Ag (BO/CBO/Ag) ternary composite material. Comprehensive characterization of the ternary composite using a variety of techniques confirmed fast electron channelization, improved charge carrier separation and prolonged life time of the excited state. The ternary composite exhibited excellent photocatalytic activity for 17-α Ethinylestradiol (EE2) degradation (94.6%) and Cr(VI) reduction (96.9%) under visible light irradiation with an apparent rate constant value of 0.0185 min−1 and 0.1147 min−1 , respectively. The hydroxyl (•OH) and superoxide (•O 2 −) radicals were identified as the major active species responsible for photocatalytic action. The electron transfer mechanism in BO/CBO/Ag material is probed using photoelectrochemical characterization and spectroscopic method (PL, UV–Vis and ESR) employing different molecular probes. The substantially staggered band alignment between the BO and CBO semiconductors and formation of an internal electric field at the interfacial region ensures smooth passage of electron from the CB of BO to the VB of CBO forming a step (S) scheme heterojunction. The Ag metal acts as an electron reservoir as well as surface Plasmon which help in achieving higher charge carrier separation and improved photocatalytic activity. [ABSTRACT FROM AUTHOR]

• A novel UiO-66/CdIn 2 S 4 heterostructure material is devised by integrating CdIn 2 S 4 nanosheets with UiO-66 nanoparticles. • Hierarchical 3D- microflower structure with high surface area, large interfacial contact and improved optical absorption. • A constructive band alignment facilitates easy migration of electrons from CB of CIS to UiO-66. • Photoelectrochemical study confirms better channelization of charge carriers and high resistance to recombination. • UiO-66/CIS nanocomposites exhibit efficient TCS degradation (0.0094 min−1) and H 2 production (2950 μmol g-1 h-1) activity. Construction of porous heterostructure photocatalyst material with improved surface and optoelectrical properties is a practical and effective strategy for mineralization of toxic organic pollutants and water splitting reaction under visible light irradiation. Herein, we have developed a facile hydrothermal route to prepare a series of novel UiO-66/CdIn 2 S 4 heterojunction nanocomposite materials containing finely dispersed UiO-66 spherical nanoparticles (20−40 nm) anchored over high aspect ratio CdIn 2 S 4 nanosheets. Comprehensive characterization of the UiO-66/CdIn 2 S 4 nanocomposites revealed a hierarchical 3D microflower structure with enhanced surface reactive sites, better channelization of charge carriers, high resistance to charge recombination and a favorable band alignment between the two semiconductor components. The optimal photocatalyst (30UiO-66/CdIn 2 S 4) showed improved photocatalytic efficiency towards triclosan degradation with rate constant (0.0094 min−1) twelve times higher than the pure CdIn 2 S 4 (0.0007 min−1). The 30UiO-66/CdIn 2 S 4 photocatalyst also exhibited higher H 2 evolution rate (2.95 mmolg−1 h−1) with apparent conversion efficiency of 20.8 %. [ABSTRACT FROM AUTHOR]

• A simple one pot hydrothermal method is designed for synthesis of CdS/BiOBr/Bi 2 O 2 CO 3 heterostructure photocatalyst. • A double z-scheme electron transfer process leads to enhanced separation and migration of charge carriers. • Improved optical and photoelectrochemical properties and prolonged life time due to high interfacial contact. • The ternary heterostructre show excellent photocatalytic activity for mineralization of atrazine herbicide. • MTT assay study confirms the non-cytotoxic nature of the treated aqueous solution of atrazine. In this study, a simple one-step hydrothermal method was developed for morphology controlled synthesis of CdS/BiOBr/Bi 2 O 2 CO 3 ternary heterostructure materials. The ternary system contained well dispersed CdS nanoparticles (50–80 nm) anchored over ultrathin BiOBr and Bi 2 O 2 CO 3 nanoplates with high interfacial contact. A significant enhancement in visible light absorption, prolonged life time decay and improved charge carrier separation and migration property accounted for the excellent photocatalytic activity towards atrazine herbicide degradation (>95% in 30 min). A double Z-scheme electron transfer mechanism was proposed to explain the dramatic increase in photocatalytic activity which was deduced from photoelectrochemical measurements, scavenger and radical (OH and O 2 ‾) trapping experiments. MTT assay study revealed that the photo-catalytically treated atrazine solution showed significant reduction in cytotoxicity. This study provides an effective strategy for facile synthesis of bismuth based ternary heterostructures with potential applications in the field of environmental remediation. [ABSTRACT FROM AUTHOR]