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Herein, we reported the synthesis of BiOX (X = Cl, Br) with different grinding time like 15 min and 30 min to analyze the evolution of physiochemical properties and the morphological evolution. The structural, optical, vibrational properties were examined by standard characterization studies. The formation of bismuth oxyhalides were confirmed by XRD and Raman studies. The crystallite size was decreased as in 30 min grinded sample whereas there is an influence of crystal structure. BiOCl (15 and 30 min) samples expelled the nanoflake like structure with the flakes arranged to form a nanoflower morphology. On comparing BiOCl (15 min), there is high orientation of nanoflakes on BiOCl (30 min) sample. As explored in BiOBr (15 and 30 min) samples, the development of nanoplates were found. The growth of nanoplates was enhanced in the better way in BiOBr (30 min) than BiOBr (15 min). The grinding time has explored a great influence on morphology. The photocatalyst test for prepared photocatalysts was performed to reduce the RhB dye. The photocatalysts showed 74%, 97%, 98% and 99.8% for BiOCl (15 min), BiOCl (30 min), BiOBr (15 min) and BiOBr (30 min). The rate constant value obtained was 0.008, 0.011, 0.021, 0.033 and 0.068 min -1 . BiOBr (30 min) sample achieved higher rate constant value. The hierarchical nanostructures and narrow bandgap has made the samples to be a potential candidate to reduce the toxic pollutants with complete efficiency., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

A facile synthesis of pristine and g-C 3 N 4 loaded CdWO 4 (Cadmium Tungstate) were reported and analyzed the effect of pollutants removal in wastewater. The samples were characterized and the morphology of the pristine sample showed the nanostructures with high cluster of layer formed. While adding PEG (Polyethylene glycol), the surface has exhibited less agglomeration and in g-C 3 N 4 added sample the agglomeration was intensely reduced and nanostructures have been clearly found. Photocatalytic performance on cationic dye was investigated under visible light. The efficiency calculated for g-C 3 N 4 - CdWO 4 sample was 85% for MB. The C/C 0 plot gives better degradation. The kinetic study revealed pseudo first order reaction. The g-C 3 N 4 -CdWO 4 sample exhibited higher "k" value which proved best efficiency on removing the pollutant. g-C 3 N 4 -CdWO 4 sample will make better reduction on toxic pollutants and be a good candidate in futuristic applications. By carbon based derivates inclusion with photo active materials, the morphology and surface area was greatly improved and it enhances activity of host material and it will be the promising material for industrial applications., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Herein we reported the effect of doping and addition of surfactant on SnO 2 nanostructures for enhanced photocatalytic activity. Pristine SnO 2 , Zn-SnO 2 and SDS-(Zn-SnO 2 ) was prepared via simple co-precipitation method and the product was annealed at 600 °C to obtain a clear phase. The structural, optical, vibrational, morphological characteristics of the synthesized SnO 2 , Zn-SnO 2 and SDS-(Zn-SnO 2 ) product were investigated. SnO 2 , Zn-SnO 2 and SDS-(Zn-SnO 2 ) possess crystallite size of 20 nm, 19 nm and 18 nm correspondingly with tetragonal structure and high purity. The metal oxygen vibrations were present in FT-IR spectra. The obtained bandgap energies of SnO 2 , Zn-SnO 2 and SDS-(Zn-SnO 2 ) were 3.58 eV, 3.51 eV and 2.81 eV due to the effect of dopant and surfactant. This narrowing of bandgap helped in the photocatalytic activity. The morphology of the pristine sample showed poor growth of nanostructures with high level of agglomeration which was effectively reduced for other two samples. Product photocatalytic action was tested beneath visible light of 300 W. SDS-(Zn-SnO 2 ) nanostructure efficiency showed 90% degradation of RhB dye which is 2.5 times higher than pristine sample. Narrow bandgap, crystallite size, better growth of nanostructures paved the way for SDS-(Zn-SnO 2 ) to degrade the toxic pollutant. The superior performance and individuality of SDS-(Zn-SnO 2 ) will makes it a potential competitor on reducing toxic pollutants from wastewater in future research., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Metal molybdate families such as AMoO4 [A = Ni, Co, Cu, Mn] in transition metal series have received considerable great attention in energy storage and conversion applications. Among these metal molybdates, CoMoO4 is widely used in various industrial applications. CoMoO4 was prepared using solvothermal method. Monoclinic CoMoO4 was confirmed. Metal–oxygen (M–O) bonding, crystal defects, chemical bonding, surface morphology, particle size, and elemental composition were analyzed. The specific capacitance of prepared electrodes was estimated and obtained the high specific capacitance of 561 F/g, 768 F/g, and 1039 F/g, respectively. Long-term stability of CoMoO4 under ethanol solvent revealed the capacitance retention of about 96% even after 16 h. Hence, CoMoO4 nanostructures will be a probable electrode material for water-splitting applications. [ABSTRACT FROM AUTHOR]

Pure and gradient amounts of cerium (Ce)-doped zinc oxide (ZnO) were synthesized by a co-precipitation method and then their photocatalytic activities were inspected. X-ray diffractometer patterns of the pure and Cedoped ZnO nanostructures exhibit hexagonal wurtzite crystal structure. Field emission scanning electron microscopic images show that the ZnO nanospindel morphology is changed into two-dimensional (2D) polar surface-oriented nanosheets by a cerium doping level up to 0.06 mol.%. The red-shift in the near band edge emission and strong defect states emissions (blue and green) are observed in ZnO with respect to the Ce doping level. From the detailed photocatalytic experiments, the maximum methylene blue dye degradation, 86.9%, is observed on the 0.06 mol.% Ce-doped ZnO photocatalyst. The eventual conclusion is that the edges of the (001) crystallographic facet attach to each other to form a ZnO nanosheet morphology at a specific ratio of Ce doping that serves as a good photocatalyst for methylene blue dye degradation. [ABSTRACT FROM AUTHOR]

The influence of processing parameters on the physicochemical properties of hematite α-FeO nanostructures was investigated. X-ray diffraction results revealed the hematite phase rhombohedral structure. Scanning electron microscope results explored nanospheres, nanohexagonal platelets, nanoellipsoids, distorted nanocubes, and interconnected platelets nanostructures. Rhombohedral single-phase hematite was confirmed through five Raman active modes. 2 P (1) → 2 P transition in photoluminescence spectra and Fourier-transform infrared spectroscopy band observed at ~ 555 cm revealed the hematite formation. The highest specific capacitance value of 151.09 F/g for scan rate of 10 mV/s was obtained for the hydrothermal-assisted product using an Fe(NO)·9HO precursor in KOH electrolyte solutions. [ABSTRACT FROM AUTHOR]

Metal doped NiO nanoparticles have been prepared by microwave method without adding surfactants. The effect of the metal dopants on the structural, morphological, optical, and magnetic properties of the NiO nanoparticles was investigated. Metal dopant ions played a major role in reducing crystallite size and introducing lattice distortion in the doped nanoparticles. The incorporated ion takes enough oxygen from NiO lattice site, and it forms nickel interstitials (Ni i ) and oxygen vacancies (V O ) which have a predominant ionic effect observed in the PL spectrum. The magnetic properties discussion indicates that the metal doped NiO nanoparticles exhibit ferromagnetic behaviors at 10 K and 300 K. [ABSTRACT FROM AUTHOR]

Cubic-structured NiO, CoO and spinel-structured NiCoO were synthesized via microwave route. The structural properties of NiO, CoO and NiCoO nanostructures were investigated by X-ray diffraction analysis, and it showed smaller crystallite size for NiO than CoO and NiCoO by using Williamson-Hall method. Flake-like and hexagonal plate-like morphologies were ascertained from HRSEM and TEM analyses. Optical properties of these materials were investigated by photoluminescence study, and it presents the band edge emission for all materials with supplementary emissions in visible region due to the presence of defects such as vacancy and interstitial. Raman and FTIR spectra provide the functional characteristics of NiO, CoO and NiCoO nanostructures. XPS measurement revealed the purity and composition of these nanostructures. Room temperature magnetic measurements were investigated using vibrating sample magnetometer. The low coercivity and remanent magnetization for NiO, CoO and NiCoO nanostructures confirmed that these nanoparticles exhibit a weak ferromagnetic behaviour. [ABSTRACT FROM AUTHOR]

Thin films of tungsten oxide (WO) nanostructures were grown on indium tin oxide coated glass substrates by thermal evaporation technique under oxygen and argon (O/Ar) mixed gas atmosphere. The films were characterized by X-ray diffraction, Raman spectroscopy and field emission scanning electron microscopy to study the structural and morphological properties of the grown films. Three different shapes of nanostructures (one dimensional nanorods, two dimensional nanosheets and three dimensional nanosized orthorhombic structures) were formed due to the variations of growth conditions such as substrate temperature and oxygen/argon flow rate. In particular, the flow rate of oxygen plays an important role in controlling the nucleation and growth of WO nanostructures. The ethanol gas sensing properties of the films were investigated under different concentrations (10-50 ppm) at room temperature, which reveals that the sensitivity of the sensor was greatly enhanced with the increasing gas concentration. This result indicates that the WO films are good candidate for sensing ethanol gas in low concentration at room temperature. [ABSTRACT FROM AUTHOR]

Co 3 O 4 nanoparticles were synthesized by microwave process using citric acid as a capping agent. Interestingly, when calcination temperature is increased to 600 °C, nanoparticles were formed into nanospheres of about less than 20 nm observed from SEM images. The particles were aggregated into bigger size of about 65 nm when the calcination temperature was increased to 800 °C. The samples calcined at 400 °C and 800 °C show superparamagnetism above the blocking temperature and the existence of small ferromagnetism is observed when T < T b . At 600 °C, sphere like Co 3 O 4 particles exhibit complete super paramagnetism from 5 K to 300 K. These results indicated that the structural, optical and magnetic properties may be tuned by choosing appropriate calcination temperature of the sample. [ABSTRACT FROM AUTHOR]

The rapid synthesis of ZnO nanostructures by microwave treatment of aqueous solutions of different pH values is reported for the first time. Microwave in various wattages was used as the source of heating or energy feeding the aqueous precursors. The pH of the zinc metal source was altered by a suitable amount of mineralisers. The considered pH values are 8, 10, 12 and 13.5. Microwave dielectric heating is dependent on the ability of the material to absorb microwave. This is responsible for molecular friction and dielectric loss, which as a result produce internal heating of the dielectric medium, in this case the solution. In typical microwave assisted synthesis, the total exposure to the microwave treatment was near about 25 to 35 minutes. The ZnO nanostructures obtained were studied by XRD, SEM and TEM characterisations. From the XRD pattern and the full width half maximum of the dominant reflections, microstructural parameters of the nanostructures are calculated and compared for the different pH values. Flower petal like flakes and hexagonal nanorods are formed for the lower and higher pH solutions, respectively. From the SEM images, the size distributions for the pH 12 and 13.5 cases are compared by drawing a histogram. [ABSTRACT FROM AUTHOR]

• Bi dopant effect on Cu 3 (VO 4) 2 showed higher current density 1.29 mA/cm2. • Long time stability of photoelectrode for 6 h of illumination was reported. • Phase changing mechanism of Bi in copper vanadate were proposed. Producing clean energy by using low cost and efficient photoelectrodes via hydrothermal method was achieved. Bare CuV 2 O 6 monoclinic structure and structure/phase changing mechanism of Bi dopant in CuV 2 O 6 and conversion mechanism of Cu 3 (VO 4) 2 anorthic phase from CuV 2 O 6 monoclinic was revealed by X-ray diffraction (XRD). Band gap variations of two different phases and dopant, morphological effect on band structure of product were examined. Photoelectrochemical performance of fabricated electrodes was analyzed by linear sweep voltammogram (LSV), electrochemical impedance spectra (EIS), and chronoamperometry (CA) studies under illumination. Synergistic effect of nanoflower morphology and Bi dopant effect on Cu 3 (VO 4) 2 phase showed higher current density of 1.29 mA/cm2 in LSV with high electronic conductivity. Long time stability of same photoelectrode for 6 h of illumination was reported. Phase and morphological changing mechanism of Bi dopant in copper vanadate were proposed and proficient electrode was suggested for efficient photoelectrochemical water splitting. [ABSTRACT FROM AUTHOR]

CuO is generally considered as an efficient energy material for potential applications. Pure and M (Ni, Co, Zn) doped CuO@GCE modified electrodes have been fabricated via cost effective solvothermal route for electrochemical water oxidation process. Full-fledged electrochemical oxidation of water achieved by Co doped CuO@GCE modified electrode exhibited the current density of 4.41 mA/g at 2.1 V vs RHE with lower Tafel slope value of 67 mV/decade. Incorporation of foreign ions in CuO lattice supported to promote the overall charge transportation mechanism of CuO@GCE modified electrode which revealed by decreasing the charge transfer resistance (Rct) arc. Moreover, 100% of retention was achieved for Co co-catalyst incorporated CuO@GCE modified electrode even after 24 h of stability performance. Hence, it can be recommended that optimized synthesis and fabrication techniques assisted optimum co-catalyst preferred CuO@GCE modified electrode is strongly ascribable as an efficient, binder free, robust and scalable electrode for electrochemical water oxidation and various potential applications. • Co doped CuO@GCE exhibited current density of 4.41 mA/g at 2.1 V vs RHE. • Co doped CuO@GCE exhibited lower Tafel slope value of 67 mV/decade. • 100% of retention was achieved for Co doped CuO@GCE even after 24 h. [ABSTRACT FROM AUTHOR]

Highlights • Zr-α-Fe 2 O 3 nanoflakes were synthesized employing solvothermal. • High conductivity, lowest Tafel slope (83 mV/decade) were attained. • High photocurrent (1.69 mA/cm2) was obtained. • 16.17% intrinsic photon conversion efficiency achieved with photostability. Abstract To investigate the oxygen evolution reaction of overall water-splitting process, Zr-doped α-Fe 2 O 3 nanostructures were synthesized by employing one-pot solvothermal route. This work reported the electrochemical and photoelectrochemical (PEC) properties of synthesized photoanodes depending on solvothermal treatment time (i.e., 12, 16, and 20 h) maintained during synthesis. The treatment time influenced the morphology of Zr-doped α-Fe 2 O 3 nanostructures, which directly exert an effect on the electrochemical and PEC performance of the synthesized photoanodes. The high conductivity and lowest Tafel slope value (83 mV/decade) were attained from electrochemical studies for the nanoflake morphology. The highest photocurrent of about 0.52 mA/cm2 at 1.5 V Vs RHE was obtained for Zr-doped α-Fe 2 O 3 nanoflakes and 16.17% intrinsic photon conversion efficiency was achieved for the same sample with high photostability for 2 h under continuous irradiation of light. We reported the treatment time-dependent morphology effect on both electrochemical and PEC water oxidation of Zr-doped hematite nanoflakes in this work. [ABSTRACT FROM AUTHOR]

Nowadays, electrochemical water splitting is a securing alternative for clean-energy production and also an efficient expertise for oxygen and hydrogen production. Compared to single metal-based electrocatalyst, multi metal-based electrocatalyst offers more active sites, high surface area, and distinctive nanostructure for effective water oxidation. In this work, nickel and cobalt co-doped MnCO 3 was successfully synthesized via a facile co-precipitation technique. Rhombohedral crystal phase of MnCO 3 nanostructures and its crystallite sizes were thoroughly analyzed by the XRD spectra. Incorporation of doping element such as Ni and Co in MnCO 3 nanostructures exhibited two different morphologies which enhanced the catalytic performance of the prepared samples. Large surface area and porosity of the nanomaterials improved the stability and activity of the prepared MnCO 3 nanostructures. EDX analysis confirmed Mn, C, O, Ni and Co elements in stoichometric ratio. Moreover, the specific capacitance of (Ni, Co) co-doped MnCO 3 nanostructures attained 581 F/g while the other electrodes attained only 207, 332 and 175 F/g respectively. A small Tafel slope with low overpotential of Ni, Co co-doped MnCO 3 nanostructures was 20.2 mV/dec and 293 mV respectively. Therefore, the prepared electrocatalysts of Ni, Co co-doped MnCO 3 nanostructure is one of the attractive anode material for high performance energy conversion applications. • Ni, Co co-doped MnCO 3 attained 581 F/g while others attained 207, 332 and 175 F/g. • Ni, Co co-doped MnCO 3 explored low 293 mV overpotential. • Ni, Co co-doped MnCO 3 is attractive anode for high performance energy conversion. [ABSTRACT FROM AUTHOR]

Hydrogen is one of the popular abundant elements in the world and, it is rising as a preferential energy and has developed a tool for decarbonization. Recently, hydrogen has been considered as next generation fuel for cars, trucks, homes, etc, because of the arising of worse climate. In this present work, the cost-effective and efficient electrocatalyst of calcium molybdate nanostructures were successfully prepared with the help of non-ionic surfactant (PEG) through the co-precipitation method for hydrogen evolution reaction. In XRD spectra, the high crystallite peak observed at 28.4° value corresponded to (112) lattice planes confirmed the formation of calcium molybdate nanostructures. In Raman spectra, the existence of tetrahedral [MoO 4 ] clusters and octahedral [CaO 8 ] clusters confirmed tetragonal calcium molybdate nanostructures formation. In SEM analysis, unique morphologies such as dumbbell and spindle-like structures was observed, which was achieved by using the PEG. The pore volume, pore diameter and specific surface area of CaMoO4–6 ml PEG were found to be 0.149 cc/g, 11.685 nm and 28.07 m2/g respectively. Electrochemical performance confirmed that the CaMoO4–6 ml PEG nanostructures exhibited superior HER activity with the low 198 mV overpotential at 10 mA/cm2 and lesser 204 mV/dec Tafel slope value. The charge transfer resistance of CaMoO4–6 ml PEG was 0.65 Ω, which has smaller than that of other electrocatalysts such as pure CaMoO4 (24.9 Ω), CaMoO4–2 ml PEG (2.47 Ω) and CaMoO4–4 ml PEG (2.04 Ω). The excellent HER activity was explored elevated electronic conductivity, mesoporous nature, high surface area and, unique morphology. [Display omitted] • CaMoO4–6 ml PEG explored 0.149 cc/g, 11.685 nm pore volume and diameter, 28.07 m2/g surface area. • CaMoO4–6 ml PEG exhibited superior HER activity with 198 mV at 10 mA/cm2 and lesser Tafel slope value of 204 mV/dec. • Excellent HER activity attributed high electronic conductivity, mesoporous nature, large surface area and, unique morphology. [ABSTRACT FROM AUTHOR]

Treatment of wastewater for reuse is an important strategy undertaken to deal with water scarcity. In this study, pure and La-doped barium ferrites were produced using a facile hydrothermal technique. Lanthanum was doped at 1% and 2% molar ratio and the obtained product was analyzed for further confirmation of crystal structure, optical properties, vibrational properties, and morphology. X-ray powder diffraction pattern confirmed material formation. Bandgap energies were estimated from a Tauc plot. The vibrational properties of the pure and doped samples were examined by Fourier-transform infrared spectra. The pure barium ferrite sample showed a spherical agglomerated morphology. The 1% La-doped barium ferrite sample showed reduced agglomeration and the particles were attached together. The 2% La-doped barium ferrite sample showed small nanoballs with no agglomeration on the surface. The transmission electron microscopy images confirmed no agglomeration for the 2% La-BaFe 2 O 4 sample. The M–H loop revealed the ferromagnetic behavior of the pristine and doped samples. The 2% La-BaFe 2 O 4 sample had 24.53 m2/g surface area. The photocatalytic activity was examined employing degrading methylene blue under ultraviolet (UV) and visible light. Prepared product showed better efficiency on UV light exposure. The 2% La-doped barium ferrite sample exhibited almost 80% of efficiency under UV light and 85% efficiency under visible light toward toxic pollutants. The sample attained 0.02 min−1 rate constant value. The main advantage of ferrite samples is that the particles can be separated by magnetic methods and the water will be fit for reuse. The sample will be a promising candidate for use in the wastewater treatment. [Display omitted] • 2% La-BaFe 2 O 4 product exhibited good nanostructures. • 2% La-BaFe 2 O 4 showed enhanced efficiency on reducing toxic pollutant. • 2% La-BaFe 2 O 4 exhibited 85% efficiency towards toxic pollutant. • 2% La-BaFe 2 O 4 sample will be the potential candidate for wastewater treatment. [ABSTRACT FROM AUTHOR]

Abstract: The low temperature mineralization of zinc oxide nanorod bunches from zinc precursor solution mixed with the cationic surfactant Cetyl Trimethyl Ammonium Bromide is reported. Five different combinations of zinc precursor and surfactant ratios are chosen and their properties are compared using the average particle size, lattice parameter ratio () of hexagonal ZnO from X-ray diffraction, the morphologies from SEM, TEM and their optical characteristics by using optical absorption spectroscopy spectrometry. A surfactant lowers the surface tension of the solution, and forms a thermodynamically ordered and a disordered phase wherein, ordered phase seeds the growth of the ZnO nanostructures. A peculiar circular structure called ‘micelle’ is formed by the surfactant. The heads, located on the peripheries of the micelle, are the ordered phase in the solution, and are the original nucleation sites of the Zinc Oxide nanostructures. This fashion of nucleation is the reason for the ‘arms of the wheel-like’ morphology consisting of nanorod bunches. Out of the five combinations experimented, the 3:1, 3:2, 1:1 ratios show nearness in the standard value. The photoluminescence spectrum shows UV emission in the region of 380 nm and weak blue emission. The UV–VIS–NIR spectrum has exhibited a characteristic UV-absorption. [Copyright &y& Elsevier]

Pure and alkaline metal ion (Mg, Ca, Sr, Ba) doped Cerium oxide nanostructures were successfully synthesized by hydrothermal method. The structural, optical and compositional studies of the prepared nanoparticles were undertaken by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), photoluminescence (PL), Raman, X-ray photoelectron spectroscopy (XPS) and TEM analyses. The photocatalytic activity of prepared nanoparticles was analyzed using methylene blue dye. XRD pattern reveals that the prepared nanoparticles are polycrystalline nature and there is no any by-product related peaks were observed for the doped samples. The incorporation of dopants into the CeO 2 nanoparticles was confirmed through PL, Raman and XPS spectra. The enhanced photocatalytic activity for the alkaline metal doped samples was observed compared to pure cerium oxide nanoparticles. [ABSTRACT FROM AUTHOR]

Gadolinium (Gd) doped zinc oxide (ZnO) nanoparticles (NPs) with hexagonal wurtzite structure was synthesized via a co-precipitation method. The structural properties of synthesized pure and Gd doped ZnO NPs were investigated by X-ray diffraction analysis and it showed smaller crystallite size for pure than Gd doped ZnO. HRSEM analysis revealed spindle like morphologies for the synthesized NPs. Optical properties of the nanoparticles were investigated by photoluminescence study and it revealed band edge emission for all synthesized materials with additional emissions in visible region due to the presence of vacancy and interstitial defects. FTIR provides the functional characteristics of pure and Gd doped ZnO nanoparticles. XPS measurement revealed the composition of nanostructures. Room temperature magnetic measurement was investigated using a vibrating sample magnetometer and showed weak ferromagnetism in Gd doped ZnO NPs, which is switched into super paramagnetism due to the further increase of Gd concentration in ZnO matrix. [ABSTRACT FROM AUTHOR]

In this paper, the structural and magnetic behavior of Ni/Mn co-doped ZnO nanoparticles (NPs) synthesized by co-precipitation method are presented. Powder X-ray diffraction data confirm the formation of a single phase wurtzite type of ZnO structure for all the synthesized Ni, Mn doped and co-doped ZnO nanoparticles. The average crystallite size of NPs is found to be 26–38 nm. FTIR and UV spectroscopic results confirm the incorporation of the dopant into the ZnO lattice structure. Photoluminescence intensity varies with doping due to the increase of oxygen vacancies. Furthermore, M-H curve demonstrates that the Ni/Mn co-doped ZnO NPs possess obvious ferromagnetic characteristics at room temperature. Our study enhances the understanding of the novel performances of transition metal co-doped ZnO NPs and also provides possibilities to fabricate spintronic devices. [ABSTRACT FROM AUTHOR]