Green Combustion Research Articles

Energetic hydrogen-bonded open-framework as promising green combustion catalyst for nitramine-based solid propellants

The development of halogen-free nitramine-based green solid propellants has attracted a significant interest due to their application in rapidly developing aerospace technologies. However, relatively low burn rates, and generation of high pressure in the combustion chamber limit applications of such propellants. The alleviation of these problems could be achieved by using suitable combustion catalysts. Herein, a new energetic nitrogen-rich open framework compound 1 was prepared and evaluated as an efficient Pb-free combustion catalyst for HMX-nitrocellulose-nitroglycerin solid composite propellant formulation. Compound 1 was synthesized by a straightforward one-step process, its structure was comprehensively characterized by x-ray crystallography, and it was found to be thermostable (decomposition at 289 °C), insensitive to mechanical impact and friction (60 J, 360 N), and showed high hydrolytic stability. A propellant formulation containing 3.0 wt.% of 1 exhibited 45% increase in its burning rate (under 6.0 MPa) versus catalyst-free reference propellant. In the pressure range of 3–10 MPa, the pressure exponent was calculated to be 0.32, which is more than two times lower than of the reference propellant. These impressive properties of catalyst 1 suggest that it has a great potential to be further used in the development of future highly energetic green solid propellants.

2-Deoxy-d-glucose functionalized zinc oxide nanodrug for kidney cancer treatment

For the first time, zinc oxide (ZnO) nanoparticles (NPs) are synthesized by the green combustion method using apple peel extract as a reducing agent. Further, ZnO-Deoxy-d-Glucose (2DG) nanohybrids were synthesized by the sputtering method. These synthesized biomolecule-coated NPs and nanohybrids are characterized with different techniques. The Bragg reflections confirm the hexagonal Wurtzite structure for ZnO. A decrease in crystallite size and an increase in energy band gap were observed for ZnO and ZnO-2DG. The tuning of the band gap plays a vital role in cytotoxicity, arbitrated by intracellular reactive oxygen species. The cytotoxic properties, such as the percentage of inhibition and the percentage of the proliferation of ZnO and ZnO-2DG nanohybrid, are examined against the Kidney cancer Vero cell line and also compared with the standard drugs Levofloxacin and Doxorubicin. Compared to ZnO, ZnO-2DG shows excellent cytotoxic properties, even better than the standard drug against the Vero cell line. Thus, the present ZnO-2DG nanohybrid might be used as a nanodrug and go on to replace Levofloxacin and Doxorubicin as standard drugs in kidney cancer cell therapy.

Excellent photoluminescence and electrochemical properties of Sm3+ doped Ca2MgSi2O7 nanophosphor: Display and electrochemical sensor applications

A series of orange-red light emitting Ca2MgSi2O7:Sm3+ nanopowders were fabricated via low-cost eco-friendly green combustion technique using Aloe vera gel as fuel. The phase purity of the samples were confirmed by the powder X-ray diffraction (PXRD) technique. Pure single-phase tetragonal structure is observed from the PXRD results with no additional impurity peaks. The band gap energy of the fabricated powders was estimated by diffuse reflectance spectra (DRS) and is found to be in the range of 4.01–5.98 eV. A high resolution scanning electron microscope (SEM) was used to study the morphological behaviour of the samples. Honeycomb-like structures are observed from the SEM results. The particle size was evaluated by transmission electron microscopy (TEM) and is found to be ∼50 nm. The interplanar distance is found to be 0.53 nm. Photoluminescence properties were systematically studied in detail. The phosphors are successfully excited at 403 nm NUV light, producing reddish-orange characteristic emission. The emission peaks are centered at 558 (4G5/2 → 6H5/2), 607 (4G5/2 → 6H7/2) and 645 nm (4G5/2 → 6H9/2), respectively. Among the observed peaks the red emanation (4G5/2 → 6H7/2) is stronger than the orange emission (4G5/2 → 6H5/2) in the current investigation. The photoluminescent concentration quenching is noticed above 5 mol% Sm3+ ion doping content. The dipole–dipole interaction resulting in cross relaxation is found to be the principal cause of concentration quenching mechanism. The color features such as Commission Internationale de l’Eclairage (CIE) and correlated color temperature (CCT) were studied in detail. The optimized chromaticity coordinates were estimated to be (0.6363, 0.3632), which fall in the reddish-orange region. The average CCT value obtained is 3362 K. The average color purity is found to be ∼82%. Sm3+ incorporated Ca2MgSi2O7 samples are possible contender for single white light generation commercial candidates owing to their strong hypersensitivity of Sm3+ ions through host, least possibility for re-absorption of blue-green emission owing to poor direct f–f excitation of Sm3+ ions, and high color purity (reddish-orange emission). The prepared powders exhibit excellent electrochemical redox properties and CPE modified optimized powders show outstanding sensitive response which indicates its use in the potential electrochemical sensor materials for drug sensing studies.

Synthesis of NiO nanoparticles for gas sensor application

A green combustion technique assisted by freshly extracted tea (Camellia sinensis /natural tannic acid) was adopted to synthesize NiO nanoparticles. Further research into the physicochemical properties of the NiO nanoparticles was conducted after heating them to 350℃. The average particle size of NiO nanoparticles in their as-prepared state was found to be 18.4 nm, while the average particle size of NiO nanoparticles in their heat-treated condition was found to be 28.7 nm. The scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to record NiO nanoparticles' external morphology, particle shape, and particle size. It was discovered that the NiO nanoparticles had a spherical shape with an average particle size of 23.5 nm for the samples created as is and 34.8 nm for the heated samples. The performance assessment of the petrol sensor was carried out using a number of testing techniques and a variety of gases. NiO nanoparticles outperformed all other testing gases when it came to how effectively the sensor responded to ethanol gas. NiO nanoparticles are interesting materials for use in gas sensor applications, as evidenced by their response-recovery time.

Helianthus-annuus assisted synthesis of ZrO2 nanoparticles: Enhanced electrochemical, photoluminescent, and optical properties

Cubic-phase ZrO2 nanoparticle (NPs) were synthesized using a cost-effective single-pot green combustion method and Helianthus annuus extract, and their properties were evaluated. Powder X-ray diffraction was used to investigate the purity, crystal structure, and size of the NPs, and the average size of the NPs was determined to be ∼ 25 nm. The internal surface morphology of the NPs with distinct voids and pores were observed using scanning electron microscopy (SEM) Ultraviolet–visible (UV-vis) absorption spectroscopy was used to analyze the optical properties of the as-synthesized ZrO2 NPs, and their energy bandgap was determined to be 4.5 eV. The photoluminescence (PL) spectrum of the cubic-phase ZrO2 NPs presented a broad band in the UV-vis region. The PL emission properties of the ZrO2 NPs were studied by analyzing their emission wavelength at ∼490 nm, and the results revealed that the NPs can be efficiently used for display applications. The electrochemical properties of a graphite–ZrO2 NP electrode was qualitatively analyzed by performing cyclic voltammetry (CV) and electrochemical impedance spectroscopy experiments in a three–electrode system with a 0.1 M KCl solution as the electrolyte. Our results suggested that the NPs can be used to evaluate the thermodynamics of the redox reaction, and their capacitance was determined using the CV curves of a graphite–ZrO2 working electrode at different scan rates in the range of 0.01 ∼ 0.05 V/s at room temperature. Furthermore, the photodegradation rate of Reactive Blue 4 textile dye over the as-prepared ZrO2 NPs reached 97% under UV-vis light irradiation.

Synthesis, analysis and characterization of camellia sinensis mediated synthesis of NiO nanoparticles for ethanol gas sensor applications

A green combustion technique assisted by freshly extracted tea (Camellia sinensis /natural tannic acid) was adopted to synthesize NiO nanoparticles. Further research into the physicochemical properties of the NiO nanoparticles was conducted after heating them to 350 ℃. The average particle size of NiO nanoparticles in their as-prepared state was found to be 18.4 nm, while the average particle size of NiO nanoparticles in their heat-treated condition was found to be 28.7 nm. The scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to record NiO nanoparticles' external morphology, particle shape, and particle size. It was discovered that the NiO nanoparticles had a spherical shape with an average particle size of 26 nm for the samples created as is and 35 nm for the heated samples. The performance assessment of the petrol sensor was carried out using a number of testing techniques and a variety of gases. NiO nanoparticles outperformed all other testing gases when it came to how effectively the sensor responded to ethanol gas. NiO nanoparticles are interesting materials for use in gas sensor applications, as evidenced by their response-recovery time.

Effective paracetamol sensor activity, thermal barrier coating (TBC), and UV-light-driven photocatalytic studies of ZrxO2:Mg2+(1−x) nanoparticles

Herein, we report the synthesis of magnesia co-stabilized zirconia (ZrO2:Mg2+) NPs by a green (Helianthus annuus plant leaves extract) combustion route and their tailored characteristics for thermal barrier coating (TBC) applications.

Antiviral Properties against SARS-CoV-2 of Nanostructured ZnO Obtained by Green Combustion Synthesis and Coated in Waterborne Acrylic Coatings.

The COVID-19 pandemic has increased the need for developing disinfectant surfaces as well as reducing the spread of infections on contaminated surfaces and the contamination risk from the fomite route. The present work reports on the antiviral activity of coatings containing ZnO particles obtained by two simple synthesis routes using Aloe vera (ZnO-aloe) or cassava starch (ZnO-starch) as reaction fuel. After detailed characterization using XRD and NEXAFS, the obtained ZnO particles were dispersed in a proportion of 10% with two different waterborne acrylic coatings (binder and commercial white paint) and brushed on the surface of polycarbonates (PC). The cured ZnO/coatings were characterized by scanning electron microscopes (SEM) and energy-dispersive X-ray spectroscopy (EDS). Wettability tests were performed. The virucidal activity of the ZnO particles dispersed in the waterborne acrylic coating was compared to a reference control sample (PC plates). According to RT-PCR results, the ZnO-aloe/coating displays the highest outcome for antiviral activity against SARS-CoV-2 using the acrylic binder, inactivating >99% of the virus after 24 h of contact relative to reference control.

Eco-friendly preparation of Bi2O3, Ag-Bi2O3 and Ag-Bi2O3-rGO nanomaterials and their photocatalytic H2 evolution, dye degradation, nitrite sensing and biological applications

The current studies demonstrate the preparation of Bi2O3, Ag-Bi2O3, Ag-Bi2O3-rGO nanocomposite using a clear and concise, environmentally sustainable, low-cost green combustion method employing citrus limon as fuel. The synthesised materials were characterised through XRD, UV-DRS, FT-IR, TGA, TEM, SEM and Raman studies. The synthesised Ag-Bi2O3-rGO composite exhibited much improved photocatalytic H2 evolution activity (432.7 μmolg-1h−1) which is 5.5 times greater than bare-Bi2O3 (78.6 μmolg-1h−1) and 4.2 times greater than Ag-Bi2O3 (101.2 μmolg-1h−1) NPs. Further, Bi2O3, Ag-Bi2O3 and Ag-Bi2O3-rGO composite degraded the MB dye by 63.96, 74.9 and 100 % respectively in 90 min. Ag-Bi2O3-rGO exhibited superior electrochemical nitrite sensing property (with the LOD of 19.792 μM). Ag-Bi2O3-rGO nanocomposite exhibited potential antiradical property with IC50 of 900 μg/mL Ag-Bi2O3-rGO was found to have potent direct haemolytic, anticoagulant, antiplatelet and antibacterial activities. This study illustrates a simple, environmental friendly green synthetic technique for large-scale synthesis of multifunctional Ag-Bi2O3-rGO nanocomposite.

Photocatalytic, shielding and cytotoxic properties of reduced graphene oxide and barium ferrite nanocomposite synthesized via green combustion method

For the first time, reduced graphene oxide (rGO) and barium ferrite (BFO) nanocomposites were synthesized by using an eco-friendly green combustion method (sugar and Leucas aspera (Thumbe) leaves extract as reducing agent). Synthesized rGO/BFO nanocomposite was characterized by different characterization techniques. The PXRD pattern clearly confirms the formation of the nanocomposite, where the peaks corresponding to both rGO and orthorhombic phase of BFO co-exist. In addition to these, very few peaks corresponding to Fe 2 O 3 exist. Surface morphology clearly indicates the anchoring of BFO NPs on the rGO sheet. The energy band gap determined by Wood and Tauc's relation was found to be 2.2 eV. Optical parameters such as Extinction coefficient, Refractive Index, Absorption coefficient, and Transmission are determined from the transmission spectrum. Photocatalytic studies were carried out for the degradation of Methylene Blue (MB) dye and were monitored by UV–Vis absorption spectroscopy. Further, radiation shielding properties and Cytotoxic effects are discussed in detail. • For the first time, reduced graphene oxide and Barium Ferrite nanocomposites are synthesized by green combustion method. • The synthesized rGO/BFO nanocomposite was characterized by different characterization techniques. • The surface morphology clearly indicates the anchoring of BFO NPs on the rGO sheet. • The photocatalytic studies are carried out for degradation of Methylene Blue dye. • Further, radiation shielding properties and Cytotoxic effects are discussed in detail.

Citrus limon assisted green synthesis of MgO nanoparticles: Evaluation of phase, functional groups, surface morphology, thermal stability and colloidal stability

Citrus limon (the common lemon juice) assisted green combustion was used to create MgO nanostructures. The powder was heat treated for 3 h at 350 °C, and the as-synthesized and heat treated MgO nanostructures were tested by various techniques to investigate their phase composition, structure, thermal stability, colloidal stability, surface morphology, and antimicrobial activities. XRD was performed to study the single-phase cubic structure of MgO nanostructures, and the XRD results confirmed that the sizes of the MgO nanostructures are in the nanoscale range. The average crystallite sizes for as-synthesized and heat-treated samples are 7.8 nm and 19.2 nm, respectively. The functional groups in the experiment were examined using FTIR in the 400–4000 nm range. Thermal analysis of the MgO nanostructures were recorded through TG-DTA and the results confirm the MgO NPs thermally decomposed at 359.77 °C and 361.86 °C. The colloidal stability of the samples was tested using Zeta potential, it confirms that both samples are stable. The external morphology of as-synthesized and heat-treated samples were visualized through SEM. It confirms that the as-synthesized and heat treated MgO samples are nanostructures. The elemental analysis confirms the presence of Mg and O in both samples. The antimicrobial activity of MgO nanostructures tested by plate count mothed and the heat-treated sample exhibits noticeable antimicrobial performance against G-positive and G-negative bacteria.

Magnetically recyclable ZnCo2O4/Co3O4 nano-photocatalyst: Green combustion preparation, characterization and its application for enhanced degradation of contaminated water under sunlight

Finding the appropriate photocatalyst for elimination of organic contaminants is a challenge for remediation of environment. Herein, we tried to synthesis of ZnCo2O4/Co3O4 nanocomposite using the Stevia extract as a natural reagent that can act as green fuel in auto-combustion sol-gel method and control the size of product by steric-hindrance induced by its structure. The chelating role of this natural reagent was investigated by changing the amount of this extract for synthesis of different samples. Analyses confirmed the effect of this parameter on morphology and size of products. The photocatalytic activities of different samples under visible irradiation were investigated and the effect of size of photocatalyst on degradation percent of dye was studied. The good performance of ZnCo2O4/Co3O4 nanocomposite was detected by degradation of Acid violet 7 about 93.5% in 70 min and 2-phenol about 100% in 18 min. Photocatalyst was easily recycled through magnetic properties of products and stability of it under irradiation was confirmed by degradation of dye after 10 times recycling.

Effect of heat treatment on structural, morphological, dielectric and magnetic properties of Mg–Zn ferrite nanoparticles

Green combustion was used to prepare a ferrite composition of Mg0.4Zn0.6Fe2O4 using a blend of fresh lemon juice as a natural fuel-reductant. Effect of heat treatment on phase, morphological, dielectric, and humidity sensor properties is discussed. The formation of a cubic spinel ferrite has been established by XRD-diffraction and vibrational spectroscopic studies. The experimental lattice parameter ranges from 8.3721 to 8.3631 Å. The broadening of octahedral band (υ2) in the vibrational spectra is an identification for the existence of ferrite nanoparticles in various sizes. The typical crystallite size ranges from 10.2 to 36.9 nm. Using micrographs obtained from field-effect scanning electron microscopy (FESEM), researchers observed a spherical-shaped microstructure with agglomerated nanoparticles. Dielectric investigations have shown that the current ferrite composition has typical dielectric dispersion. The highest reported value for saturation magnetization (Ms) in the present study is 33 emu/g. Magnetic behaviour is primarily influenced by magnetocrystalline anisotropy, cation distribution, and crystallite size. The existence of void spaces in the sintered samples, as well as their porous nature, rendered them suitable for humidity sensor applications. Sintered samples have good sensing capability at 900 °C. The current findings are integrated in terms of cation distribution and magnetocrystalline anisotropy, assuming fine size effects of ferrite nanoparticles.

Facile green synthesis of lanthanum oxide nanoparticles using Centella Asiatica and Tridax plants: Photocatalytic, electrochemical sensor and antimicrobial studies

Lanthanum oxide (La2O3) nanoparticles (NPs) were prepared by the facile green combustion method using the leaf powders of Centella asiatica and Tridax plants (C-La2O3 and T-La2O3 NPs). Various analytical and electrochemical techniques were employed to understand the morphology, crystallinity, and band gap of La2O3 NPs. X-ray diffraction (XRD) studies revealed that the NPs exists in a hexagonal crystal structure with a crystallite size of 20 nm. The morphological studies (SEM and TEM) revealed La2O3 clusters with porous structures. UV-DRS (diffuse reflectance) spectra was used to arrive at the band gap of 5.44 eV and 5.61 eV for C-La2O3 and T-La2O3 NPs. The thermogravimetric studies showed a 2-step decomposition process involving La(OH)3. Electrochemical and photocatalytic studies were conducted to explore the efficiency of C-La2O3 and T-La2O3 NPs. The better photocatalytic degradation was observed for T-La2O3 NPs with 60% efficiency. In addition, La2O3 NPs also exhibited good antimicrobial activities.

Structural, optical and electrical properties of undoped and doped (Al, Al + Mn) ZnO nanoparticles synthesised by green combustion method using terminalia catappa seed extract

This paper presents the synthesis of undoped and doped (Al, Al + Mn) ZnO nanoparticles by green combustion method using Terminalia Catappa seed extract as a novel fuel and Zinc nitrate as a precursor, Aluminum nitrate and Magnesium chloride was used as dopant. Synthesized undoped and doped ZnO nanoparticles were characterized by XRD, FESEM, FTIR, UV-visible spectroscopy and impedance spectroscopy. The XRD study of undoped and doped (Al, Al + Mn) ZnO nanoparticles exhibits hexagonal wurtzite structure with high crystallinity. The crystallite size increases from 37.5 nm to 39 nm for Al doping and decreased to 30.5 nm for Al + Mn doped ZnO nanoparticles. Mean grain size of undoped ZnO nanoparticles was found to be 32.5 nm. For Al doped ZnO nanoparticles mean grain size increases (42.9 nm) and then decreases (21.25 nm) for Al + Mn doped ZnO nanoparticles. FTIR studies confirms the formation of Zn-O bond at 462, 455 and 439 cm−1 for both undoped and doped ZnO nanoparticles. The optical band gap was found to be 3.25, 3.2 and 2.54 eV for undoped and doped (Al , Al + Mn) ZnO nanoparticles respectively. The dielectric properties and conductivity studies were carried for undoped and doped (Al, Al + Mn) ZnO nanoparticles at various fixed temperatures (50 to 350 °C) by varying frequency from 10 Hz to 8 MHz. Dielectric constant increases with rise in temperature and, dielectric constant decreases with rise in frequency and remains constant at higher frequency. At lower frequencies AC conductivity was constant and increases as the frequency increases. Grain and grain boundary resistance for the synthesised ZnO nanoparticles were studied by complex impedance analysis and result exhibits a decrease in grain resistance with rise in temperature. The ZnO nanoparticles doped with Al shows improved microstructural properties, decreased optical band gap and activation energy. Hence these nanoparticles are suitable material for sensors and optoelectronics applications.

Development of enhanced electrochemical sensor and antimicrobial studies of ZnO NPs synthesized using green plant extract

The present investigation envisages for plant mediated synthesis of ZnO NPs (ZNPs) by green combustion route using eco-friendly LCL (Lantana Camara Leaf) Extract. The optical and structural characterizations of ZNPs was studied by spectral techniques; PXRD (Powder X-ray diffraction) study confirms the phase formation and crystalline nature of NPs with its average particle size found to be 35 ​nm The internal morphology of synthesized NPs comprises noticeable pores, voids and agglomeration obtained by SEM (Scanning Electron Microscopy) technique. TGA-DTA (Thermogravimetric-Differential Thermal Analysis) analysis reveals the changes in physico-chemical properties of ZNPs by the effect of temperature. The electrochemical reaction measurements of ZNPs-graphite paste electrode in a 3-electrode system using 1 ​M HCl solution was conducted by CV (Cyclic Voltametric) and EIS (Electrochemical Impedance Spectroscopy) techniques in the different scan rates 0.01–0.05 ​V/s. Further, the corrosion inhibition activities of ZNPs were examined on mild steel (MS) in 1 ​M HCl solution by electrochemical spectral studies (CV & EIS) and potentiodynamic polarization (PDP) measurements. The antimicrobial potential of ZNPs was discussed in detail in contrast to gram positive (Micrococcus luteus) and gram negative (P.auruginosa) bacterial strains by the zone of inhibition concept using disc diffusion technique.

Facile green synthesis of Molybdenum oxide nanoparticles using Centella Asiatica plant: Its photocatalytic and electrochemical lead sensor applications

The molybdenum oxide nanoparticles (MoO3 NPs) have been successfully synthesized via green combustion method using Centella asiatica plant powder. The powder x-ray diffraction (PXRD), Fourier transform infrared spectroscopic (FTIR), scanning electron microscopic (SEM) and diffuse reflectance spectroscopic (DRS) techniques were used to characterize the MoO3 nanoparticles. The PXRD patterns of the sample revealed pure hexagonal phase. The Scherrer's method was employed to find the crystallite size of the synthesized material and the result obtained was confirmed by the TEM analysis. The optical energy band gap value (Eg) of the sample was calculated using the Tauc relation, and it was found to be around 3.41 ​eV. The photocatalytic degradation of MoO3 NPs on Direct Green (DG) and Navy Blue (NB) dye was evaluated under UV light irradiation. The electrochemical study of prepared electrode with graphite powder in 0.1 ​M KOH electrolyte solution displayed superior redox potential output as intended by cyclic voltammetric and amperometric studies, where the material was employed for its sensing abilities such as a highly toxic metal like lead.

Combustion synthesis-aqueous hybridization of nanostructured graphene-coated silicon and its dye removal performance

An ultra-fast and green combustion synthesis methodology is employed to reduce quartz sea sand (SiO2) into a Mg2Si(Si)/MgO nanostructured material. Moreover, highly conductive graphene nanosheets with a specific bulk electrical conductivity of 27 S cm2 g−1 are prepared by the molten salt exfoliation of graphite in molten salt. A simple one-pot acid treating of the combustion synthesized material, and graphene nanosheets leads to the preparation of a nanostructured Si-graphene hybrid material (NSG) with clean interface, promoting the dye adsorption and photocatalyric activity of the nanostructured material, outperforming the commercially available silicon nanoparticles. The dye removal performances of the silicon materials (1.0 g L−1) are evaluated using methylene blue as the model dye with the initial concentration of 50 mg L−1 in dark and under visible blue LED irradiation with the peak output at the wavelength of 475 nm. While commercial Si nanoparticles exhibit neither considerable dye adsorption nor photocatalytic activity, 69 present of the dye is absorbed at the adsorption equilibrium within 50 min of exposure to NSG, followed by the complete dye removal upon LED light irradiation within 300 min. The enhanced adsorption and photocatalytic performance of NSG is attributed to the unique morphology of NSG, in which highly crystalline few layer graphene nanosheets with low level of structural defects are in contact with silicon semiconductor nanocrystals.

Multifunctional and smart Er2O3-ZnO nanocomposites for electronic ceramic varistors and visible light degradation of wastewater treatment.

In this proposed study, erbium (Er3+)-doped ZnO nanocomposites were prepared through the effective, basic, and green combustion method. The significant effects of Er dopants on the structural, morphological features, dielectric, and optical behaviors of the pure ZnO matrix as well as Er2O3-ZnO nanostructured materials were investigated applying X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transformation infrared (FT-IR) spectroscopy, and UV-Vis spectrophotometer techniques. These results showed that the synthesized Er2O3-ZnO nanocomposites are well polycrystalline. The Er2O3-ZnO nanocomposites are almost uniformly distributed on the surface morphologies. Furthermore, UV-Vis diffuse reflectance spectroscopy, AC electrical conductivity, and dielectric properties' current-voltage characteristics were utilized to examine the influence of erbium doping on the optical properties, energy bandgaps of the proposed Er2O3-ZnO nanostructured powder. The tested nano-samples were applied for the visible light photodegradation of p-chlorophenol(4-CP) and p-nitrophenol (4-NP). The Er-doped ZnO ratio affects the photocatalytic activity of the ZnO matrix. This current research substantiated that more than 99.5% of 4-CP and 4-NP were photodegraded through 30 min of irradiation. Four times, the Er:ZnO nanocatalysts were used and still displayed an efficiency of more than 96.5% for 4-CP and 4-NP degradations in the specified period of 30 min. The as-prepared Er2O3-ZnO nanostructures are considered novel potential candidates in broad nano-applications from visible photocatalytic degradation of waste pollutants to the electronic varistor devices.

A study on the impact of tin concentration on microstructural, dielectric and conductivity properties of ITO nanoparticles

Indium tin oxide (ITO) nanoparticles synthesized by green combustion method using Carica papaya seed extract as a novel fuel and, indium (In) and tin (Sn) as precursor is presented in this paper. Indium nitrate and tin nitrate solution were prepared by dissolving the In ingots and Sn in nitric acid. Carica papaya seed extract was prepared using dried Carica papaya seeds. Carica papaya seed extract along with indium nitrate and tin nitrate solution was heated in muffle furnace at 600 °C for 1 h. The obtained powder was calcinated at 650 °C for 3 h to obtain ITO nanoparticles. The effect of Sn concentration (5%, 10% and 50%) on microstructure, dielectric and ac conductivity of ITO nanoparticles were studied. These properties were investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM), UV–Vis spectroscopy, thermal gravimetry and differential scanning calorimetry (TG-DSC) and computer-controlled impedance analyser. The XRD analysis of synthesized ITO nanoparticles exhibits cubic bixbyite structure with increase in crystallite size from 17 nm to 22 nm as Sn concentration increases. SEM and HRTEM investigations exhibit an increase in grain size as Sn concentration increases. TG-DSC analysis reveals a constant weight in the temperature region 200 to 800 °C. The diffused reflectance spectral studies revealed that the band gap decreases from 3.01 eV to 2.75 eV as Sn concentration increases. The ac conductivity and dc conductivity of ITO nanoparticles was found to increase with increase in Sn concentration and temperature. With improved microstructural properties, higher optical band gap and increased ac conductivity, synthesized ITO nanoparticles with 10% Sn concentration are suitable material for sensor and optoelectronic applications.