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In the present communication, ZrTiO4 nanoparticles (NPs) are synthesized by the solution combustion method using urea (ZTOU) and oxalyl dihydrazide (ODH) (ZTODH) as fuel and calcined at 700 °C.

Transition metal spinel ferrites of the formula MFe2O4, (M = Co, Cu, Zn & Ni) were synthesized successfully by very simple one pot solution combustion method through glycine - nitrate route. Characterization was carried using techniques like Powder X ray diffraction (PXRD), Fourier transform Infra-red (FTIR) spectroscopy and Scanning electron microscopy (SEM), which reveals that these ferrites are in the nano crystalline size in the range of 20–60 nm. Also it displays that these spinel ferrites are in single phase and pure form. Vibrating sample magnetometer (VSM) measurements shows that all ferrites are magnetic in nature. CoFe2O4 was found to be a hard magnet whereas NiFe2O4, ZnFe2O4 and CuFe2O4 are soft magnets. To study and compare the dielectric characteristics we used impedance analyzer. Dielectric constant, loss tangent and ac conductivity was measured as a function of increasing frequency and the effect of calcination temperature was also analyzed for all the ferrites. The gradual decrease in dielectric constant and loss tangent with the rise in frequency shows that the ferrites can act as semiconductors. AC conductivity was found increasing with respect to frequency and calcination temperature of the sample. Calcination temperature effect was studied to understand the variation of different conductivity properties which gave an understanding of processing temperature.

Advances in anticancer drug discovery are focusing on the invention of drugs that specifically prompt cell death and pose lesser toxicity to the customary cells. The proposal aims at evaluating the cytotoxic potential of the non-metallic carbon dot (CDs) nanoparticles as a selective anticancer drug against targeted human carcinoma cell lines of liver (HepG2) and breast (MCF-7) in vitro. CDs were synthesized by a chemogenic method from three different natural carbohydrate derivatives glucose (GCD), sucrose (SCD), and fructose (FCD) and were characterized by UV–Visible, Fluorescence, HRTEM, ATR-IR and Raman spectroscopic techniques. Further compared for their anticancer activity against above mentioned cells. The percent cell viability investigations showed a suitability of CDs for cytotoxic studies. The IC50 of the CDs nanoparticles (SCD, GCD, FCD) on HepG2 cells were

In this rapid growing eco-friendly research world, synthesis of non-toxic, highly effective photocatalyst for potential applications is necessary. Herein, a strong ability Bi

Supercapacitors are emerging as adaptive and competitive devices for flexible and portable electronics. The flexible electronics require flexible supercapacitors to store the energy. In this connection, two-dimensional layered materials with permeable channels with excellent conductive properties are of great interest. This work gives a brief overview of synthesis, characterization and supercapacitor electrode performances of VS2 nanosheets. VS2 nanosheets were synthesized using hydrothermal reaction and characterized by microscopic and spectroscopic techniques. As synthesized VS2 nanosheets show hexagonal layered structure with nanosheets morphology. The supercapacitor electrode performances were studied by fabricating VS2 electrodes on the glassy carbon electrode and tested in a three electrode configuration. The nanosheets exhibit excellent supercapacitor electrode characteristics with a specific capacitance of 235F/g at 100 mV/s. The superior performances can be attributed to excellent electrical conductivity and fast ion transport through the layered structure.

CaZrO3 ceramics exhibits high chemical, thermal and structural stability. However, its application as a host for various luminophores/activators has not been clearly explored. In present study, CaZrO3 doped with Eu3+, as a potential orange-red phosphor and the effect of NH4Cl as flux during combustion synthesis is investigated. Ca1-xZrO3:Eux (x = 0.05) nanophosphor was prepared through a low temperature, one pot solution combustion synthesis approach using glycine as fuel. Various wt.% of NH4Cl (wt.% = 0, 1, 3, 5, 7) as flux added to the reaction mixture and combustion reaction was performed. X-ray diffraction results showed that the addition of flux has significant effect on the crystallite size and the crystallinity of Ca1-xZrO3:Eux (x = 0.05) phosphor. From SEM morphology, the particles were found to be significantly agglomerated. The extent of agglomeration varies with varying the wt.% of flux. The photoluminescence excitation and emission spectra were recorded under similar condition to evaluate the effect of flux on the optical properties. Interestingly, the amount of flux was found to have significant effect on the photoluminescence emission characteristics. The photoluminescence intensity was found to be the maximum when the flux used was 5 wt.% and further increase in flux amount the photoluminescence intensity decreases. The mechanistic aspects of effect of flux on the photoluminescence were also discussed.

Fabrication of noble metal-free semiconductor heterojunction composed of transition metal dichalcogenides (TMDs) and CdS is observed to be an efficient and economical photostable system for hydroge...

In this study, an eco-friendly, cost-effective and fast microwave method of preparation of carbon dots was employed. The antimicrobial and cytotoxic activities of metal-based nanoparticles are well known, but the effects of carbon dot nanoparticles (C-dot NPs) are less explored. Stable C-dot NPs were prepared from organic waste of pomegranate and watermelon peels and characterized by UV-visible spectrophotometer, fluorescent spectroscopy, Fourier transform infrared (FTIR) spectra, high-resolution transmission electron microscopy (HRTEM) and Raman’s spectroscopic techniques. The different biological applications of C-dots such as anti-microbial activity against Fusarium oxysporum, Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis and Escherichia coli and the cytotoxic activity against MCF-7 and HepG2 cell lines were evaluated. The study revealed that the C-dots synthesized from pomegranate peel (P-C dots) have larger effect than those synthesized from the watermelon peel (W-C dots) on therapeutic properties. C-dots synthesized by pomegranate peel extract and watermelon peel extract have shown the anti-bacterial activity at the concentration of 80 μL (19.67 ± 0.37) on bacterial strains versus ciprofloxacin at 10 μg/mL (19.67 ± 0.40) which was used as control. P-C dots (61.00 ± 1.90) have shown significant antifungal activity when compared with the fluconazole (85 ± 0.90) and the W-C dots did not show any activity. Further, P-C dots and W-C dots were evaluated for cytotoxic activity. Both P-C dots and W-C dots have shown strong anti-cancer effects for cell lines; for MCF-7, P-C dots have shown significant effect when compared with W-C dots, whereas for HepG2 cell lines, both the C-dots are showing almost equal range of effects. This study reveals that the C-dots synthesized from organic wastes can be used as a therapeutic agent to treat human microbial infections.

More than a thousand tonnes of fish bone wastes can be transformed into biomedical products annually. Alkaline hydrolysis and thermal calcification were used to create nanosized hydroxyapatite (HAp) crystals from Silver carp bone wastes. Biophysical tests were used to determine the nano size and chemical composition of synthesised hydroxyapatite. Alkaline hydrolysis hydroxyapatite (AH-HAp) was 58.3 nm, while Thermal calcination hydroxyapatite (TC-HAp) was 64.3 nm in size, confirmed by Atomic Force Microscopy. Energy Dispersive X-ray Analysis studies showed Ca/P (Calcium phosphate) ratio of AH-HAp to be 1.65, whereas TC-HAp as 1.45, confirming AH-HAp to be organically rich along with a similar Ca/P ratio as natural HAp. Fourier Transform Infrared Spectroscopy spectra indicated HAp formation from both procedures, however AH-HAp had superior crystallinity than TC-HAp confirmed from X-Ray Diffraction spectra. MG63 osteoblast cell lines showed 91% cell viability in cytotoxicity studies and 70.1% proliferation efficiency in Alkaline Phosphatase assay, which was higher than TC-HAp. The present study shows that HAp produced via alkaline hydrolysis has better biocompatibility which enhances its applicability as a biomaterial, than HAp synthesized through thermal calcination, which tends to incinerate organic moieties.

Carbon dots (C-dots) developed from beetroot is used for the rational design of cadmium sulphide based heterojunction photocatalysts (C-dots@CdS) using hydrothermal technique. The crystal structure, phase, morphology and optical characteristics of the synthesised materials are determined using X-ray diffraction (XRD), High resolution transmission electron microscopy (HR-TEM), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, UV-Visible diffuse reflectance spectroscopy (UV-DRS), photoluminescence spectroscopy (PL spectroscopy), BET adsorption, X-ray photoelectron spectroscopy (XPS) and electrochemical studies. Using C-dots@CdS catalytic system, a superior photocatalytic activity relative to the undecorated CdS is observed. Among the C-dots@CdS samples, the CdS loaded with 6 wt% of C-dots exhibited enhanced hydrogen evolution rate compared with other samples considered for the study. CdS nanospheres modified with C-dots (6 wt%) resulted in the photocatalytic hydrogen evolution rate of 1582 µmolg

A single step hydrothermal mode of carbon nanodots (C-dots) synthesis from house-hold kitchen garbage such as snake gourd peel extract was successfully carried out. Characterisation of green synthesized C-dots were accomplished using UV-Visible and FTIR spectroscopy, Spectrofluorimetry and HRTEM. C-dots exhibited an appreciable quantum yield of 28.6%. Excitation-dependent photoluminescence emission properties and pH-sensitivity of C-dots were also studied in detail. C-dots exhibited strikingly selective detection of Fe3+ ions via fluorescence quenching mechanism. Linearity was obtained in a concentration range of 10–100 μM with detection limit of 0.398 μM in accordance with the Stern-Volmer relation. The existence of oxygen containing functional moieties in luminescent C-dots could be attributed to the effectual complexation between the metal ion and C-dots. The selective sensing property of C-dots towards Fe3+ ions provide avenue for biochemical analysis related to iron metabolism and diagnosis of anaemia.

Dy3+:SrY2O4 nanophosphors were prepared via a solution combustion method using glycine as an organic fuel. The structural, optical, and thermal properties of the nanophosphors were studied. Strain and crystal size were calculated via W–H analysis. The direct energy band gap is nearly 4.9 eV and photocatalytic studies reveal that Rh-B degradation of almost 50% can be achieved.

Ca1-xZrO3:xEu3+ (x = 0.05) phosphors have been prepared by using the low temperature solution combustion synthesis. The prepared nano phospors are well characterized by powder X-ray diffraction, scanning electron microscopy, Fourier infrared spectroscopy and transmission electron spectroscopy. PXRD results showed orthorhombic phase and SEM images showed porous agglomerated morphology. Influence of nitridation on structural and photoluminescence properties of the phosphor were investigated for wide range of nitridation time. The photoluminescence (PL) intensity was found to vary with nitridation with small shift in the photoluminescence emission peaks. The probable reasons for the variation of photoluminescence with nitridation are discussed.

Treating post-surgical wound is one of the major challenges in the field of medical Science due to the several disadvantages posed by the antibiotics. The antimicrobial and Wound healing activity of metal based nanoparticles were well known, but the effects of carbon dot nanoparticles (C-Dots) are less explored. In the present study a wet chemical method for the synthesis of C-Dots from sucrose, glucose and fructose was developed and they were characterized by UV-Visible, Fluorescent spectroscopic techniques and the pharmaceutical applications such as antibacterial and the wound healing activities were evaluated. The study revealed that the C-Dots synthesized from Sucrose (SCD) and Glucose (GCD) showed potent antibacterial activity against both positive and negative bacterial strains at 12.5µl/ml (0.1 ± 0.003) and Fructose (FCD) at 50 µl/ml (0.1 ± 0.01) compared to the vehicle Control (0.61 ± 0.06). The wound healing of SCD (367.8 ± 15.2) was observed better than the Control (280.8 ± 10.72) and FCD (326.8 ± 9.41). GCD (166.8 ± 10.83) skin tissues indicated best healing as compared to FCD (135.8 ± 8.29), SCD (157.3 ± 16.97) and Control (135.8 ± 8.29). The results suggest that C-Dots applied topically possess wound healing activity and have potential applications as a bacteriostatic agent.

Nickel-doped cobalt ferrite nanoparticles based on Andrographis paniculata plant extract were prepared through the microwave-assisted method. The obtained nanoparticles were analyzed using XRD, FTIR, UV-DRS, SEM with EDAX, and HRTEM with SAED. XRD exhibits a cubic lattice structure of ferrites and the lattice parameter decreases with an increase in nickel dopant. The vibrational stretching mode of the metal–oxygen bond is observed for tetrahedral and octahedral sites. The optical energy bandgap of pure CoFe2O4 nanoparticles gradually increases with nickel doping. The luminescence spectrum showed the violet, yellow, green, and orange emissions of synthesized nanoparticles. Further, photodegradation of prepared nanoparticles was assessed for the degradation of Methylene blue, Rhodamine B, Eriochrome black T, Rose bengal, and Evan’s blue dyes. Antibacterial activity of synthesized nanoparticles was tested against Gram-positive and Gram-negative bacterial strains. The antibacterial activity improved with Ni doping when compared with pure CoFe2O4 nanoparticles.

The inorganic nanoparticles based semiconductor photocatalyst has attracted widespread attention for the practical applications in sustainable energy and environmental remediation due to its low cost, eco-friendly, high efficiency and ease of process. CuS, CdS and CuS CdS nanocomposite photocatalysts have been successfully synthesized by a simple hydrothermal approach. The phase purity, composition and surface morphology of as synthesized nanomaterials were characterized using various analytical techniques. The photocatalytic activities of the as-prepared materials have been evaluated by the degradation of methylene blue (MB) dye in the presence of hydrogen peroxide (H2O2) which served as an oxidant under visible light irradiation. MB dye (10 ppm) was degraded by about 80%, 59% and 99.97% for CuS, CdS and CuS CdS nanocomposite respectively at 10 min. The results demonstrate that CuS CdS nanocomposite exhibited excellent photocatalytic activity as compared to the CuS and CdS is which mainly attributed to large surface area, narrow band gap, high adsorbing capacity of the dye and also low recombination of the photo-generated electrons and holes. Further, electrochemical impedance (EI) measurement revealed that as prepared CuS CdS nanocomposite suggested that as compared to CuS and CdS, the CuS CdS nanocomposite exhibits rapid migration of photo-induced charge carriers. In addition, the CuS CdS nanocomposite demonstrated that good stability towards photocatalytic degradation even after repeated usage. Finally, a suitable photocatalytic reaction mechanism has been proposed to indicate the photocatalytic performance of the nanocomposite.

Carbon dots (CDs) endowed with outstanding physico-chemical characteristics expeditiously garnered tremendous popularity in the scientific community. CDs can be synthesized from a variety of natural resources and can replace metal semiconductor quantum dots in the range of applications such as bio-imaging, sensing and catalysis. Herein, CDs are green synthesized from Beta vulgaris via a single step hydrothermal approach (b-CDs). The synthesized carbon dots are characterized using UV–visible spectrophotometry, Fluorescence spectroscopy, High resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), x-ray diffraction technique (XRD) and Raman spectroscopy. The b-CDs hence developed exhibited the signature ‘excitation-dependent fluorescence emission’ with its most intense emission in the green region. The quantum yield for the b-CDs obtained by this synthetic approach evinced an appreciable value of 11.6%. The antioxidant property of b-CDs are evaluated using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay to obtain a maximum scavenging activity of 94.5% at a concentration of 1000 μg ml−1 and its underlying mechanisms are illustrated. The blood compatibility of b-CDs are assessed using haemolysis assay and the cytotoxicity evaluated using MTT assay shows significant cell growth-inhibition against the human breast cancer (MCF-7) and hepatocellular carcinoma (HepG2) cell lines. This succinct study demonstrates the inherent therapeutic potential of biocompatible carbon dots.

The present experiment explains the effectiveness of adsorption studies of methylene blue dye from aqueous solutions on activated carbon from Selenicereus grandiflorus (SG) treated with conc. sulfuric acid. The sulphuric acid-treated Selenicereus grandiflorus activated carbon (SGAC) was used as low-cost adsorbent for the removal of methylene blue dye from aqueous solution. It suggests an ideal alternative method to adsorption of dye compared to other expensive treatment options. The adsorption studies have been conducted at different experimental parameters, i.e., pH, contact time, adsorbent dose and initial dye concentration. The batch mode experiments were conducted by different adsorbent dose (0.03-0.150 g per 50 mL), pH of the solution (2-12), effect of time (3-18 min), initial dye concentration (10 mg/L), point of zero charge and regeneration of spent adsorbent studies. Langmuir model shows better fit to the equilibrium data (R2 = 0.966) than Freundlich model. The adsorption capacity (Qm) of SGAC increases with increasing dosage where Qm is 16.17 mg g-1.

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CaZrO3 ceramic pigment exhibits high chemical, thermal and structural stability. However, its application as a host for various luminophores/activators has not been clearly explored. In the present investigation, CaZrO3 doped with Eu3+, as a potential orange-red phosphor has been demonstrated. Ca1-xZrO3:Eux (x = 0.01–0.09) nanophosphor is prepared here through a low temperature, one pot solution combustion synthesis approach using glycine as the fuel. X-ray diffraction results show that all the samples are stabilized in orthorhombic crystal structure without any impurity phases. Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high resolution TEM are carried out to determine the microstructure of the phosphor. The particles are found to be significantly agglomerated and in the nano-regime (∼40 nm). The observed excitation spectrum suggests that Ca1-xEuZrO3 can be efficiently excited using ultra-violet (UV), near-UV and UV blue (UVB), making it immediately relevant for current solid state lighting technologies. In fact with every ∼1 at% doping increase, the primary excitation line intensity increases by a factor of ∼1.5; this provides a simple parameter to enhance the UV excitability of the phosphor. The color coordinates are deduced using the Commission International De Eclairage (CIE) co-ordinates (x, y = 0.58, 0.40). The critical distance of energy transfer in this system is determined to be ∼10.7 A, making multipole-multipole interactions as the plausible reason for concentration quenching beyond 7 mol.% Eu doping. The luminescence behaviour of the material is evaluated using Judd-Offelt (JO) intensity parameters. Judd-Ofelt (JO) intensity parameters (Ω2 and Ω4) are calculated for the sample Ca1-xZrO3:Eux (x = 0.01–0.09), in order to understand the local structure around the activator. Irrespective of the concentration of Eu3+, Ω2 is found to be greater than Ω4, indicating asymmetric environment around the activator. Furthermore, with increase in Eu3+, Ω2 increases suggesting an increase in covalency of Eu-O bonds with significant effect of host crystal field on Eu3+.

Carbon quantum dots (CQDs) due to its high fluorescent output is evolving as novel sensing material and is considered as future building blocks for nano sensing devices. Hence, in this investigation we report microwave assisted preparation and multi sensing application of CQDs. The microwave derived CQDs are characterized by Dynamic Light Scattering (DLS) experiment and Fourier Infrared spectra (FTIR) to investigate the size distribution and chemical purity respectively. Fluorescent emission spectra recorded at varying pH shows varying fluorescence emission intensities. Further, emission spectra recorded at different temperatures shows that fluorescence emission of CQDs greatly depends on temperature. Therefore, we demonstrate the pH and temperature sensing characteristics of CQDs by fluorescence quenching behaviour. In addition, the interaction and sensing behaviour of CQDs for dopamine is also presented in this work with a detection limit of 0.2 mM. The steady state and time-resolved methods have been employed in fluorescence quenching methods for sensing dopamine through CQDs at room temperature. The bimolecular quenching rate constants for different concentration have been measured. The interaction between CQDs and dopamine indicates fluorescence quenching method is an elegant process for detecting dopamine through CQDs.

The simultaneous electroanalysis of acetaminophen (AC), guanine (G) and adenine (A) was successfully achieved on the zinc sulphide nanoparticles-modified carbon paste electrode (ZnS NPs/CPE) in phosphate buffer solution (PBS). Zinc sulphide nanoparticles (ZnS NPs) were prepared through a simple co-precipitation method and characterized via various spectroscopic techniques. The detailed studies confirmed that the as-synthesized ZnS NPs grew as high-density crystalline structures and they exhibit good electrocatalytic properties. The proposed method is selective and sensitive toward the development of an electrochemical sensor. The modified electrode showed acceptable reproducibility and stability under optimal conditions with high-accessible surface area and antifouling properties. The as-synthesized ZnS NPs enhanced the oxidation peak current and reduced the peak potential of AC, G and A. Furthermore, the sensor showed two linear ranges over the concentration from 1 to 15 μM and 15 to 120 μM. Based on the calibration plot, the limit of detection (LOD) was calculated and found to be 0.041, 0.036 and 0.031 μM for AC, G and A, respectively.

Solution combustion synthesized ZnO (SCSZ) and commercially available Degussa P-25 TiO2 was tested for the photocatalytic degradation of Brilliant Yellow (BY) under both UV/Solar light. Powder X-ray Diffraction (PXRD) results revealed crystalline wurtzite phase with P63mc space group for combustion derived ZnO. The scanning electron micrographs (SEM) of ZnO sample shows that the powder products are voluminous and porous. Diffused Reflectance Spectral studies indicated the extension of the band gap to the visible region for ZnO due to its smaller crystallite size. Fourier transform infrared spectra (FTIR) of as-formed SCSZ displayed strong band at 425 cm-1 which confirms the stretching vibration of Zn-O bond. SCSZ showed enhanced activity for the degradation of BY under UV/solar light compared to Degussa P-25 which was attributed to high crystallinity, large surface area of the sample and enhanced degree of hydroxylation on the surface of ZnO.

In the present investigation nano copper ferrite, CuFe2O4 (CF) is synthesized by one pot energy saving solution combustion synthesis. The combustion derived copper ferrite nanoadsorbent is characterized by powder X-ray diffraction, Fourier transform infra-red spectroscopy, scanning electron microscopy, transmission electron microscopy and UV–Vis spectroscopy. The magnetic behavior is studied by Vibrating sample magnetometer measurements and the results shows it’s a soft ferromagnet with low saturation magnetization and coercive effect. CF nanopowder is used as good magnetically separable nanoadsorbent. Adsorption property is evaluated by the removal of malachite green, a dye which is widely used by many industries, from its aqueous solution. Various parameters like contact time (5–30 min), adsorbent loading (0–45 mg) are investigated systematically by batch experiments. Adsorption isotherms and kinetic studies also conducted which shows that the adsorption follows pseudo second order mechanism. The experimental data fitted well with the Langmuir isotherm (R 2 = 0.978), yielding a maximum adsorption capacity of 22 mg/g. The optimum adsorbent dose was found to be 40 mg/L and stirring time experiment reveals that 85% of decolourization was observed for 30 min of stirring at neutral pH which is much more efficient than those reported in literature. Graphical abstract

Carbon quantum dots (CQDs) are novel fluorescent nanomaterials and elegant building blocks for future nano devices, and have garnered much interest as potential competitors to conventional semiconductor quantum dots. Herein, we report the microwave assisted synthesis of carbon quantum dots of size less than 10 nm and the synthesis of Zinc oxide nanoparticles (ZnO) by combustion method. The synthesized ZnO nanoparticles were characterized by X-ray diffraction, field emission scanning electron microscope and high resolution transmission electron microscope. Due to hazardous effect of ZnO nanoparticles on human health, its detection is important. The fluorescence quenching method has been employed to study the interaction between CQDs and ZnO nanoparticles involving steady state and time resolved measurements at room temperature. The interaction between CQDs and ZnO nanoparticles were studied, due to excellent overlap between the donors’ (CQD) emission spectrum and the acceptors’ (ZnO nanoparticles) absorption spectrum, Forster's resonance energy transfer theory is applied to measure the distance between the donor and acceptor ( r 0 = 5.56 nm) as well as the critical energy transfer distance ( R 0 = 55.6 A).

A single step hydrothermal mode of carbon nanodots (C-dots) synthesis from house-hold kitchen garbage such as snake gourd peel extract was successfully carried out. Characterisation of green synthesized C-dots were accomplished using UV-Visible and FTIR spectroscopy, Spectrofluorimetry and HRTEM. C-dots exhibited an appreciable quantum yield of 28.6%. Excitation-dependent photoluminescence emission properties and pH-sensitivity of C-dots were also studied in detail. C-dots exhibited strikingly selective detection of Fe

The photocatalytic efficiency of semiconducting catalytic material is greatly influenced by one of the important factor like band gap. In the area of sustainable energy and environmental decontamination, ZnO photocatalysts have been extensively used. However, there is a significant decrease in the photocatalytic performance of ZnO due its large band gap, and fast recombination of charge carriers. Various methods have been designed to address this issue, such as nanostructuring, chemical doping, introducing oxygen defects, surface sensitization, and employing nanocomposites. Here, the semiconducting ZnO, ZnO/GO were prepared by simple co-precipitation method and solid state reaction respectively. The synthesised ZnO, ZnO/GO catalysts were characterized thoroughly by different techniques such as X-ray diffraction (XRD), Raman spectroscopy, Fourier Transform infrared Spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), Diffuse reflectance spectroscopy(DRS), photoluminescence (PL), BET specific surface area. The Eg values of ZnO/GO has found to be 2.71 eV which is lower than the bare ZnO (2.81 eV), which is benefit to have higher photocatalytic activity. The performance of synthesized catalysts was explored for remediation of CV dye by employing visible light as energy source to begin photoreaction. The ZnO/GO nanohybrid has shown 99% degradation of CV in 240 min under neutral pH and rate constant found to be 0.01514 min−1 which is much higher than bare ZnO. In ZnO/GO nanohybrid, the phenomenal photocatalytic efficacy was attributed to the suppressed charge carriers (electron in CB and holes in VB) recombination and adequate injection of photosensitized electron in the hybrid during the photocatalytic reaction. Further, GO itself acts as electron collector and transporter and thereby furnishes electrons for enhancing the photocatalytic reaction by providing reactive oxygen species and hydroxyl radicals for the degradation of crystal violet. Addtionally, the interrelationship between the physical properties like band gap and catalytic competence were founded.

ZnO nanoparticles are prepared by green synthesis using Moringaoleifera natural extract. XRD and Raman analysis show crystalline ZnO with wurtzite structure. SEM and TEM images show the average size of the nanoparticles to be 100–200 nm. Photocatalytic generation of hydrogen by these nanoparticles has been investigated under UV–Visible light irradiation. Na 2 S and Na 2 SO 3 sacrificial agents dispersed with the photocatalyst are employed as hole scavengers. ZnO nanoparticles with smaller size shows better H 2 evolution rates up to 360 μmol hg −1 . It is noteworthy that ZnO nanoparticles prepared via novel green synthesis exhibits oxygen vacancies and registers enhanced photocatalytic activity as well as good photostability.

Copper sulphide nanoparticles (CuS NPs) were synthesized by simple co-precipitation method in aqueous media using starch as a biopolymer. The obtained product was characterized by XRD, SEM, EDX, TEM, FTIR and UV–vis techniques. The particle size was determined by TEM analysis and found to be in the range 20–50 nm. CuS NPs modified carbon paste electrode (CuS NPs MCPE) was employed to determine caffeine (CAF) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. The CuS NPs MCPE showed better electrocatalytic activity towards the oxidation of CAF, which was confirmed by enhance in the oxidation peak current and decrease in oxidation peak potential. Furthermore, in electrochemical impedance (EI) studies, the charge transfer resistance (RCT) at CuS NPs MCPE (12.1 kΩ) decreases as compared to bare CPE (42.6 kΩ), which suggests that CuS NPs improves the charge transfer capacity of CPE. Electron transfer kinetic parameters, sensitivity and surface active area of the electrode were determined. Under experimental conditions, the oxidation current of CAF was proportional to its concentration from 2 μM to 120 μM. The detection limit was found to be 18 × 10−9 M. The developed method was successfully applied to determine CAF content in food samples with appreciable results.

‘Nanocarbon science’ ignited interest owing to its substantial scope in biomedicine, energy and environment-beneficial applications. Carbon dots (C-dots), a multi-faceted nanocarbon material, emerged as a homologue to graphene and henceforth geared extensive investigation both on its properties and applications. Eximious properties like excitation-wavelength tunable fluorescence emission, up-converted photoluminescence, photon-induced electron transfer, low cytotoxicity, chiroptical behavior, high chemical and photostability set the ground for astounding applications of carbon dots. Abundant availability of raw ‘green’ precursors complementary to other molecular/graphitic precursors make them environmentally benign, inexpensive and ultimately ‘nanomaterials of the current decade’. This review focuses on the synthesis of carbon dots not only from natural sources but also from other carbonaceous precursors and contemplates the inherent but controversial properties. We also aim to garner the attention of readers to the recent progress achieved by C-dots in one of its prestantious area of applications as nanosensors.

Visible light active photocatalytic processes have gained much interest in removing the organic pollutants from wastewater. In this article, we report the ZnO prepared by a simple co-precipitation method and characterized by PXRD, FE-SEM, TEM, DRS, and FTIR. The photocatalytic activity of ZnO assisted by H2O2 was examined for the degradation of the aqueous solution of Crystal violet (CV) under visible light. The combination of ZnO and H2O2 has enhanced the activity compared to bare ZnO or H2O2 alone under visible light. The influence of H2O2, Catalyst amount, CV concentration and pH were studied. The ZnO nanostructures in the presence of H2O2 exhibited highest photodegradation rate of CV solution under alkaline pH. The observed photodegradation efficiency by the ZnO photocatalyst under visible light is due to the deep level defects within the band gap, which induced in the course of the preparation method of the ZnO nanostructures, which shifts the absorption wavelength band to the visible light region. The ZnO assisted by H2O2 maintained good photostability and repeatability after 4 cycles of degradation under visible light.

Full solar spectrum absorbers are widely pursued for applications related to photocatalysis and photovoltaics. Here we report multivalent Cu-doped ZnO nanoparticles which exhibit full solar spectrum absorbance and high photoactivity. Metathesis-based, green-chemical approaches with synthesis yield of similar to 100% are used. Cu incorporation in ZnO results in an increase of average solar spectrum absorbance from a mere 0.4% to 34%. On the other hand, (Zn, Cu)0 composites result in materials with up to 64% average solar spectrum absorbance. Doped systems operate well under both visible and UV illumination. The nanomaterials prepared are characterized by using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analysis, and X-ray photoelectron spectroscopy (XPS). Photocatalysts explored have particle sizes >= 50 nm. This is deliberately done in order to avoid the nanotoxic size regime of ZnO. Despite the large particle size and low specific surface area (

Magnetic nano crystalline ZnFe2O4 was successfully synthesized by simple combustion route using oxalyldihydrazine as fuel and the material formed was characterized by powder X-ray diffraction, Fourier transform infra-red spectroscopy and scanning electron microscope. Surface area measurements (90.004 m2 g−1) were done using Brunauer–Emmett–Teller analysis. Magnetic measurements done using vibrating sample magnetometer shows that ZnFe2O4 nanoparticle is superparamagnetic. Adsorption capability of the as prepared nanospinel ZnFe2O4 was measured for the removal of Evans Blue, an anionic dye by batch adsorption process. Parameters like adsorbent loading, initial dye concentration and stirring effects were carried out at neutral pH and room temperature. Spinel ZnFe2O4 nanoparticles showed good adsorptive capacity and the maximum monolayer coverage (Q0) was determined as 46 mg/g of the adsorbent. The data were analyzed by three different kinetic models viz; Lagergren pseudo first order, pseudo second order and Intraparticle diffusion models and by various isotherm models like Langmuir, Freundlich and Temkin models to study the mechanism of adsorption process. Kinetic study shows that it follows pseudo second order with highest R 2 = 0 . 998 and the rate determining step was found to be intraparticle diffusion. Isotherm studies shows that the adsorption of EB is highly favorable and the value of Temkin constant, A T = 0.5445 and heat of adsorption, B = 14 J/mol indicates that the adsorption process is exothermic and physical in nature.