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This work describes the hydrothermal method for synthesizing a novel nanocomposite: Nickel -doped Cerium oxide on reduced graphene oxide (Ni-CeO2/rGO). The resulting material exhibits exceptional electrocatalytic behavior, showing promise for supercapacitor applications. The Phase morphology, elemental analysis, surface area and oxidation state were confirmed by powder X-ray diffraction studies (PXRD), Raman spectrum, High Resolution Transmission Electron Microscopy (HRTEM), Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray (EDX), Brunauer-Emmett Teller (BET) and XPS respectively. Electrochemical analysis involving cyclic voltammetry (CV), Galvanostatic charge/ discharge, and Electrochemical impedance spectroscopy (EIS). The specific capacitance is 262.1Fg-1, 504Fg-1, and 728Fg-1 for CeO2, CeO2/rGO, Ni-CeO2/rGO it depicts its suitability for energy storage. This study establishes the Ni-CeO2/rGO nanocomposite as a highly effective material for advanced energy storage applications.

Scientific interest in antimicrobial pollutants, such as ciprofloxacin, has increased. Due to spread of antibiotic-resistant bacteria, resistance genes, and their dissemination to the environment. Therefore, their remediation is necessary to ensure ecological sustainability. The current study aimed to optimise the removal of ciprofloxacin from synthetic water using jamun seed (JS) (Syzygium cumini) biochar using a response surface methodology (RSM). Result indicates ciprofloxacin elimination efficiency ranged between 32.46 and 94.95%, indicating the material can be improved and used for remediation of organics. The residual standard error of 4.4% were found for the predicted model, implying that the model is credible and can be used to predict future experimental findings. The R-squarred value for the improved Langmuir model's R2 is 0.9681 which is inclose agreement with the Freundlich isotherm, R2 0.9757. Therefore, JS biochar could be utilized for the remediation of ciprofloxacin from contaminated water and wastewater for ecological safety and sustainability.

The efficient manufacture of nickel oxide nanoparticles (NiO NPs) using a novel solution combustion method that makes use of chemical (glucose) and green (Aloe vera gel extract) fuels is reported in this work. As revealed by electron microscopy, the synthesized samples were spongy, spherical, agglomerated, and porous; in contrast, the face-centered cubic crystal structure (FCC) phase for NiO NPs was corroborated by PXRD. The energy band gaps of NiO NPs are 4.09 and 4.21 eV. Using an eco-friendly NiO electrode, cyclic voltammetry investigations demonstrated good reversibility (a reduced value of EO-ER). Its great conductivity was confirmed by electrochemical impedance tests, which also showed a low charge-transfer resistance. Using NiO NPs, stable electrode materials for application in supercapacitors can be readily created. In comparison to chemically synthesized NiO green generated NiO in a 3-electrode setup demonstrated a capacitance of 156 Fg−1 and 183 Fg−1 at a scan rate of 5 Ag−1, respectively, according to the GCD investigation. It also had good cycling stability, retaining more than 85% of its original capacitance after 2000 cycles. The results suggest that green produced NiO could be a cheap and practical material for use in supercapacitor applications in the future.

La10Si6O27: Tb3+ (1–9 mol%) materials were synthesized by the combustion method and characterized by PXRD, PL, CV, EIS and UV–Vis spectroscopy to explore its photoluminescent, electrochemical and photocatalytic properties. These materials exhibited crystalline and single phases even after doping Tb3+ ions into the lattice of La10Si6O27. PL analysis confirms a tunable and maximum emission for optimized concentration. Electrochemical analysis shows La10Si6O27:Tb3+ (9 mol%) electrode as a paracetamol and penegra sensing material. The average specific capacitance of this electrode at 10 mVs−1 was found to be 262 Fg−1. A Photocatalysis study was performed using La10Si6O27:Tb3+ (5 mol%) material as a photocatalyst for the degradation of direct green dyes. Therefore, La10Si6O27:Tb3+ can be used as a multifunctional material for photoluminescence, photocatalysis, and electrochemical sensing applications.

Nanocrystalline titanium oxide nanoparticles (TiO2 NPs) were synthesized by using a low-cost sonochemical method. TiO2 NPs exhibited anatase phase and an average crystallite size of 40.64 ​nm, according to a powder X-ray diffraction (PXRD) investigation. SEM and TEM images revealed spherical shape, with asymmetric geometries for TiO2 NPs. The micrographs thoroughly corroborated the plate-like structure for the NPs. In order to confirm the average energy gap of TiO2 NPs, diffused reflectance spectroscopy (DRS) via Kubelka-Monk function was applied (3.66 ​eV). Navy blue dye was used to study the photocatalytic properties of NPs and discovered to be triggered at 590.9 ​nm. The photodegradation rate of NB dye decolorized up to 74.04% after 120 ​min of UV light exposure. The first order kinetics was indicated by a linear relationship between log C/Co and k. The demonstrated rates of photodecoloration for NB under UV light in the presence of scavengers AgNO3, ethanol, and ethylenediamine tetraacetic acid (EDTA), were found to be 65.50%, 61.46%, and 57.33%, respectively. Using the carbon paste electrodes and cyclic voltammetry (CV) in 0.1 ​N HCl solution, the electrochemical characteristics of the obtained sample were studied. The carboxymethyl cellulose sensor made from TiO2 NPs demonstrated a remarkable sensitivity of 0.08 A. The results showed a high recovery for lead with low% of RSD values. The TiO2 electrode is a promising electrode material for sensing applications due to its outstanding electrochemical performance.

In this paper, we report on the synthesis of strontium oxide nanoparticles (SONPs) using a novel probe sonication method. Powder X-ray diffraction (PXRD) was used to characterize the physicochemical properties of the prepared materials, which confirmed that the average SrO crystallite size was 43 ​nm. The Kubelka-Monk function of diffuse reflectance spectroscopy (DRS) was used to confirm the average energy gap of SONPs (4.06 ​eV). SONPs have been successfully used in conjunction with inventive photocatalysts to remove dyes such as Methylene Blue (MB) and Acid Green (AG). MBand AG dyes were used as standard dyes to investigate the photocatalytic properties of NPs when exposed to UV light and sunlight.These nanometal oxides photodegrade methylene blue (87.70%) and acid green (71.20%) dyes with remarkable efficiency when exposed to UV light. These nanometal oxides demonstrated superior sensitivity when paracetamol was used as an analyte in cyclic voltammetry tests at various scan speeds (10 ​mV/s to 50 ​mV/s). As a result, SONPs may be useful in photocatalytic activity and electrochemical sensor applications.

Hybrid nanostructured materials currently offer a potential approach for a variety of applications due to improvements in their physio-chemical characteristics. Techniques for XRD, TEM-HRTEM, SAED, and UV-DRS were used to characterize the Cu2ZnAl2O4 (CZA) material. Without any secondary phases and with an average crystallite size of 40 ​nm, X-ray diffraction pattern examination demonstrates the increased crystalline structure. A highly crystalline, polydisperse CZA nanostructure was visible using TEM-HRTEM and SAED. The CZA nanostructure's light-absorbing behavior is presented by UV-DRS analysis, which found that the predicted bandgap energy was 5.0 ​eV. In this article, we describe an easy chemical synthesis of a hybrid CZA nanostructure that works well as a catalyst to break down the acid red 88 (AR-88) dye under UV, sunlight, and low light conditions. Additionally, it was studied to determine how to modify the working electrode's surface to enable the detection of lead and tin metal ions. With 93.1% of degradation and comparison work on decolorizing AR-88 dye in the presence of both sunlight and darkness, CZA nanostructure was looked at as a potential catalyst for the decolorization of AR-88 dye. By using graphite electrode paste and cyclic voltammetry to analyze the synthesized sample in 1 ​N KCl, it was discovered that it had outstanding redox reaction and lead and tin detection capabilities.

An economic low-temperature self-ignition solution combustion method was used to synthesize 1–11 mol% chromium ion (Cr3+) doped MgAl2O4 nanoparticles (NPs). The structural, morphological and energy gap variations due to the influence of Cr3+ on the host matrix were evidenced by powder X-ray diffraction (PXRD), Fourier transformed infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS), and transmission electron microscopy (TEM). Under visible light irradiation, the as-prepared NPs showed excellent photocatalytic activities (PCA) for the industrial dye Acid Red-88 (AR-88) and pyrocatechol (PY) - an emerging pollutant (EP). The experiments were carried out at room temperature in an aqueous solution at a concentration of 20 ppm. Among others, MgAl2O4:Cr3+(5 mol%) showed 91.38% degradation within 150 min exhibiting zero-order kinetics and 82% degradation in 6 h displaying the first order kinetics for AR-88 dye and PY EP, respectively. In this case, a greater number of hydroxyl (OH.) radicles dominate over other reactive oxygen species (ROS), such as holes and singlet oxygens (1O2) under different pH conditions. Electrochemical studies have yielded the proton diffusion coefficient (D) value as large as 2.145 × 10−4 cm2s−1 for the optimized NP electrode, which is substantially greater than 1.0935 × 10−5 cm2s−1 for the pure MgAl2O4 one owing to the intercalated anions and structurally disordered density of the electrode material. This superior electrochemical behaviour suggests the potential application of the optimized NP material as an anodic electrode for supercapacitors.

The present work deals with the synthesis of cerium oxide (CeO2) nanoparticles (CONPs) using sodium hydroxide and cerium nitrate as precursors via Sonochemical route. As synthesized, cerium oxide nano powders were calcined at 1000 °C to 1100 °C for 2 hrs. The obtained CONPs were characterised by using the advanced analytical methods. XRD (X-ray diffraction) analysis confirmed the pristine cubic fluorite structure for CeO2 NPs. The FTIR spectrum shows a strong broad band around 800 to 900 cm−1, for Ce-O stretching vibration to confirm the formation of pure CeO2. The particle size of CONPs was found to vary between 35 and 38 nm. Under UV light irradiation of the commercial dye methylene blue, these nano metal oxides demonstrated significant efficiency in photo degradation. A specific capacitance value of 59.78 Fg−1 was obtained from the cyclic voltammograms of the CeO2 electrode in 0.1N HCl solution with a scan rate of 10 to 50 mV/s. These electrodes have proved to be very sensitive towards the detection paracetamol. These findings revealed that CeO2 is an effective photocatalyst and a suitable electrode material for detecting paracetamol with high electrode reversibility.

The unique features of graphene materials make them excellent catalysts for photodegradation and energy applications. In the present work, CeO2/reduced graphene oxide (rGO) nanocomposites were prepared by a simple one-pot hydrothermal method. The nanocomposite is found to have a mesoporous structure with a surface area of 100.129 m2g−1. With the preferentially small surface area of the nanocomposite and the ability of the rGO to act as electron acceptor, the CeO2/rGO photocatalyst supresses the electron-pair recombination during photodegradation, thereby achieving a quick and efficient degradation of Direct Green dye. Under the influence of UV light, the CeO2/rGO degrades 84.1% of the dye which is 1.5 times more efficient than blank CeO2. Further, due to the conducting nature of rGO, the nanocomposites have also been evaluated for their electrochemical performance. It has been found that the addition of rGO results in a high capacitance (410.8 Fg−1 at current density of 1.0 Ag−1) and stability (94% after 500 cycles) of the CeO2/rGO electrode. The present work projects the excellent charge transport capability of rGO based CeO2 nanomaterials for dual applications in the areas of photocatalysis and electrocatalysis.

The current study comprises the synthesis, characterization, electrochemical, and photoluminescence studies on La1-xDyxOCl (0 ≤ x ≤ 0.09) compound by the solid-state method which exhibits a tetragonal phase. The synthesized materials bandgap is determined to be between 4.16 and 4.26 eV. The presence of Lead and Tin in a 0.1M KOH solution was detected using a modified carbon paste electrode of La0.95Dy0.05OCl. Because of the lower value of EO-ER, the cyclic voltammetry (CV) results imply that La0.95Dy0.05OCl has improved electrochemical characteristics. This La0.95Dy0.05OCl material may be a good electrode for sensing molecules like Lead and Tin. The samples radiated white light owing to major two emission bands corresponding to the 4 F 9/2 → 6 H 15/2 and 4 F 9/2 → 6 H 13/2 transitions. Judd–Ofelt parameters Ω2 and Ω4 and other radiative parameters are evaluated. The CIE chromaticity coordinates are close to the white emission standards set by NTSC, hence present phosphors may be useful in the development of WLEDs.

In the present investigation, the wet chemical combustion method was used for the first time to prepare La10Si6O27 phosphors by incorporating Dy3+(1–11 mol %) cations (LNPs). The powder X-ray diffraction patterns of LNPs display the oxyapatite hexagonal phase. The estimated crystallite size, using Scherer's method, is between 20 and 30 nm and the same was confirmed via Transmission Electron Microscopy (TEM). The bandgap energy (Eg) values calculated from diffuse reflection data were in the range of 5.6–5.72 eV. The emission spectrum is composed of characteristic transitions of Dy3+ cations (intra 4f), namely 4F9/2 → 6H15/2 (blue-479 nm), 4F9/2 → 6H13/2 (yellow-578 nm) and 4F9/2 → 6H11/2 (red-670 nm) under near-UV excitation energies. The emission results confirm the choice of using LNPs in applications of white light emitting diodes and the same was found in Color chromaticity coordinates. The white emission intensity was attributed to inherent defects, in particular oxygen vacancies which could contribute to the transfer of energy from the host to dopant ions. The results from current–voltage (CV) and electrochemical impedance spectra (EIS) show the strong electrochemical properties of LNPs. The solution of paracetamol and sildenafil (Penagra) was effectively sensed using modified carbon paste electrodes. LNPs showed a good photocatalytic activity (PCA) for Orange Red (OR) dye under UV light irradiation. These results indicate that the synthesized LNPs are a good candidate for displays, waste water treatment and for the use as electrochemical sensors.

In order to explore an alternative photocatalyst for environmental remediation, we report the sol-gel process for the synthesis of strontium titanate (SrTiO3) nanoparticles (STNPs). The as-synthesized STNPs were found to poses cubic perovskite-type crystal structure with an average crystallite size of 22 nm were well-characterized by X-ray diffraction (XRD). The agglomerated and cubic like morphologies were identified by using scanning electron microscopy (SEM). The elemental analysis by energy dispersive X-Ray spectroscopy (EDAX) confirmed the composition of STNPs. The synthesized nanoparticles were further characterized by Fourier transform infrared (FTIR) analysis. STNPs displayed good photocatalytic degradation activity for malachite green (MG) and rhodamine blue (Rh–B) dye pollutants under UV light irradiation in the time duration of 120 min. Furthermore, cyclic voltammetric studies revealed that the STNP electrode, because of its increased surface area, produced maximal specific capacitance of 208.47 Fg−1 at 1 mA/cm2 with a high cycle stability of 1500 cycles. The superior supercapacitance behaviour of SrTiO3 electrode materials strengthens its stance to be developed as a highly promising material for energy related applications. In addition, STNPs can serve as better materials for the environmental remediation of pollutant dyes.

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.

In this study, nanocrystalline cupric oxide was produced using a basic, low-cost sonochemical method (CuO). Through powder X-ray diffraction, the phase and nanocrystalline nature of CuO nanoparticles (NPs) were determined. The Kubelka-Monk function revealed that the band gap of CuO in diffuse reflectance spectra (DRS) is 1.75 ​eV. Ingenious photocatalysts for the removal of the dyes Direct green (DG) and Fast orange red (F-OR) have been demonstrated to work with CuO NPs. To examine the photocatalytic characteristics of NPs under UV light and sunlight irradiation, Direct Green (DG) and Fast Orange Red (F-OR) dyes were utilised as traditional dyes. Direct green dye was found to be excited at 624.1 and 623.8 ​nm in UV and sunlight, while Fast orange red dye is excited at 496.8 and 495.1 ​nm. Lead in 0.1 ​N HCl solution was detected using the cyclic voltammetry (CV) method with a modified carbon paste electrode (MCPE). According to electrochemical performance, CuO is an advantageous sensing electrode material for an element like lead.

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.

The rare earth (RE = Eu, Sm, Dy, and Tb) ions doped La10Si6O27 nanophosphor was synthesized by a simple solution combustion method. The prepared La10Si6O27:RE3+ nanophosphors (LNPs) were subjected to diverse technical tools for exploring their structural, optical, morphological, and electrochemical features. The structural analysis using powder X-ray diffraction (PXRD) patterns revealed the hexagonal oxy apatite phase for LNPs with a crystallite size in the range of 25–50 nm, and the equivalent was affirmed by image analysis via transmission electron microscopy (TEM). Utilizing DRS data, the bandgap energy (Eg) values were recorded for LNPs. Cyclic voltametric (CV), electrochemical impedance spectroscopy (EIS), and sensor studies were performed using a modified carbon paste electrode of LNPs. The modified LNP electrodes were found to be highly effective in sensing paracetamol in acidic medium with a quick response time of 3 secs for sensing the drugs at 1 mM concentration. All the RE ions Eu3+, Sm3+, Dy3+, and Tb3+ (5 mol%)-doped LNPs exhibited the most promising electrochemical sensing characteristics.

The dysfunctioning of β-cells caused by the unspecific misfolding of the human islet amyloid polypeptide (hIAPP) at the membrane results in type 2 diabetes mellitus. Here, we report for the first time, the early-stage interaction of hIAPP oligomers on the DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine) lipid membrane using electrochemical parameters. Electrochemical techniques are better than other techniques to detect hIAPP at significantly lower concentrations. The surface level interactions between the peptide (hIAPP) and lipid membrane (DMPC) were investigated using atomic force microscopy (AFM), confocal microscopy (CM) and electrochemical techniques such as Tafel polarization, cyclic voltammetry (CV), differential pulse voltammetry (DPV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). Inserting IAPP into the fluid domains results in breaking the lipid-to-lipid interaction, leading to restriction of membrane mobility. The SLateral values of the liposome and IAPP co-solubilized liposome indicates the cooperative insertion of IAPP. Further, a new method of immobilizing a membrane to the gold surface has been employed, resulting in an electrical contact with the buffer, preventing the direct utilization of a steady-state voltage across the bilayer. The electrochemical studies revealed that the charge transfer resistance decreased for 3-mercaptopropanoic acid modified gold (MPA-Au) electrode coated with the liposome and after the addition of IAPP, followed by an increase in the capacitance. The present study has opened up new dimensions to the understanding of peptide-membrane interactions and shows different experimental approaches for the future researchers in this domain.

Nano ferrite bentonite clay composite (NFBC) is synthesized in this present work by using manganese (Mn) recovered from waste batteries, ferric nitrate and citric acid prepared by simple and cost-effective Indian sodium bentonite nanoclay (Na-IB) by sol-gel process and by using X-ray diffractrometer (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) Spectroscopy, Energy dispersive Spectroscope (EDS) characterized nanoparticles. The result shows that NFBC is sufficient for the excellent performance of AO dye photocatalytic degradation (98 %). Electrochemical study of prepared material with graphite electrode paste in 0.1 M KCl electrolyte showed excellent redox potential output as calculated by cyclic voltammetry and expanded its sensor activities to biochemical (Dextrose). We examined the efficacy of NFBC in the detection of Dextrose from an aqueous solution and compared the results with pristine MnFe2O4 NPs.

Zinc oxide nanoparticles (ZnO NPs) have proven record of exhibiting multifunctional properties and thus utilized for diversified applications. ZnO NPs were successfully synthesized by chemical and green routes. The Syzygium cumini plant leaf extract was used to synthesize green ZnO NPs. The chemical and green ZnO NPs were characterized by using advanced technical tools to explore their bonding, structural and morphological features. The PXRD (Powder X-Ray Diffraction) patterns confirmed the hexagonal phase of ZnO with wurtzite structure. The scanning and transmission electron microscopic (SEM and TEM) analysis revealed rectangular flake like structures for chemical ZnO whereas spherical structures were found for green ZnO NPs. Maximum antibacterial activity was observed against Pseudomonas aeruginosa bacterial strain with zone of inhibition of 14.5 mm followed by 5 mm for Klebsiellaoxytoca and 4 mm for Escherichia coli for green ZnO NPs. The percentage of inhibition was found to be 85, 29 and 50 for Pseudomonas aeruginosa, Klebsiellaoxytoca and Escherichia coli bacterial strains. The percentage of inhibition of mycelial growth observed during antifungal testing was varied from 5% to 70%. The photocatalytic efficiency of 98 % for Acid Red 88 dye degradation was recorded for ZnO NPs. Green ZnO NPs exhibited better antibacterial and antifungal activities, in addition to superior photocatalytic behaviour.

The present study confirms the application of phytochemicals of Lemon rind (LR) towards the synthesis of activated carbon using a low temperature carbonization method. The structural, morphological, and electrochemical properties of the prepared carbonized flakes epoxy (CFE) electrode has been analyzed using various characterization techniques. The electrochemical double layer capacitance (EDLC) behavior of the LR-activated carbon has been evaluated. The synthesized LR-activated carbon material exhibited flake like structure along with hydroxyl groups as confirmed by studies by scanning electron microscope (SEM), X-ray diffractometer (XRD), and Fourier transform infrared (FTIR) spectroscope. In addition, the band gap energy (Eg) has been estimated using diffused reflectance spectroscopy (DRS-UV-Vis) and found to be 2.06 eV. The electrochemical property of CFE-electrode was studied utilizing cyclic voltammetric (CV) and electrochemical impedance spectroscopic (EIS) techniques. The galvanostatic charge–discharge tests for this prepared carbon flake electrode demonstrated excellent capacitance performance, making it favorable for the fabrication of supercapacitors. These progressive results could be considered for the enlargement of novel assets to scale for power-storage utility using low-cost carbon materials in various energy storage applications as well.

The current research work presents the preparation of Samarium (1–9 mol%) doped Lanthanum Silicate (La10Si6O27:Sm3+) nanophosphors (LNPs) by means of solution combustion synthesis utilizing Oxalidihydrazide as a fuel. The prepared LNPs were described by Powder X-ray Diffraction (PXRD) studies, Transmission Electron Microscopy (TEM), Diffuse reflectance spectroscopy (DRS), Cyclic Voltammetry (CV), Electrochemical impedance spectroscopy (EIS) and Photoluminescence (PL) studies. The normal crystallite size of oxyapatite hexagonal phase LNPs were in the range of 10–20 nm as determined by Scherrer's technique and the equivalent was confirmed by TEM. Band gap energy was found in the range of 4.8–5.1 eV utilizing DRS. PL investigations of the LNPs show all the characteristic emissions of Sm3+ cations related to transitions 4G5/2→6Hj/2 (j = 5,7,9,11) and optimal emission intensity was observed for 3 mol% addition of Sm3+ ions with orange red emission as depicted in the CIE. CV and EIS results uncover the great electrochemical properties of LNPs, which detect effectively Paracetamol and Sildenafil (Penegra) utilizing modified carbon paste electrodes. Results show that the blended LNPs can be a potential candidate for displays, catalytic and electrochemical sensor applications.

ZnO: Ag (0–20 mol%) hexagonal nanostructures were prepared via the phyto-synthesis route using Chonemorpha fragrans leaf extract. The structure, morphology, and compositions of the as-formed product were characterized by powder X-ray diffraction (PXRD), Field Emission Scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Surface-enhanced area diffraction (SEAD), and Raman spectroscopy. Further, prepared nanostructures were subjected to sensor and luminescence studies. PXRD pattern shows the formation of the hexagonal wurtzite system. The Rietveld refinement analysis is used to refine structural parameters. FESEM micrographs show the agglomeration of the nanoparticles. The TEM pictures reveal the hexagonal shaped nanoparticles. The average 30 - 35 nm ranged crystallite sizes were determined using Scherrer's method which is in good agreement with the TEM. An economical and naturally responsive strategy can be the use of plant extract in the synthesis of nanostructured products. Also, studies related to sensing of paracetamol were performed using ZnO: Ag (20 mol%) indicating that it is a promising electrode material for paracetamol sensing. The identified PL emission bands indicate favorable luminescence applications for ZnO: Ag nanopowders.

Silver nanoparticles (∼30–70 nm) have been impregnated on the activated graphite powder by an electroless plating method. The so prepared silver decorated graphite powders are characterized by field emission scanning electron microscopy, powder X-ray diffraction, energy dispersive X-ray and X-ray photoelectron spectroscopy. The activated graphite powder displays a high surface coverage with tin which is essential, as this ensures a thorough and complete coating of the graphite powder with silver. The electrochemical studies of Graphite, Sn/Graphite and successive decoration of Ag–Sn/Graphite powder have been carried out using cyclic voltammetry in the potential range between −1.2 and 0.0 V at a sweep rate of 50 mV s−1 and their electrocatalytic activity for methanol oxidation has been examined in alkaline medium. The effective active surface area of Graphite and Ag–Sn/Graphite electrode are calculated to be 6.2479 × 10−5 cm2 and 6.7886 × 10−5 cm2, respectively. The impedance spectrum of the Ag–Sn/Graphite electrode displays a depressed semicircle in the high-frequency region which corresponds to low charge resistance and high capacitance. The results highlight the electrocatalytic behavior of the graphite supported silver nanoparticles, making them suitable for fuel cell applications. Keywords: Silver nanoparticles, Electro catalyst, Graphite powder, Electroless deposition, Methanol oxidation

Graphene has been a prominent choice as a base material for supporting varieties of inorganic and organic materials in scientific research and innovation due to its superior physico-chemical properties. Electrochemical sensors have been prepared by the use of a variety of nanoparticles and based on graphene which effectively supported on the surface of glassy carbon electrode through different methods. Graphene supported sensors have been utilized to detect and determine different electroactive species in samples. Many characterization techniques such as Powder X-ray diffraction (XRD), Energy dispersion spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), UV–Vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, High-resolution transmission electron microscopy (HRTEM), Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) have been successfully applied to explore the properties of graphene supported nanomaterials. Applications of the sensors have been assessed using signals from electrochemical measurements such as: cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and Differential pulse voltammetry (DPV). The results obtained from these measurements have data of wide liner range with small detection limit. Most of the results also clarified that the sensors were used to detect respective species with high sensitivity, and good stability. The electrochemical sensing of H2O2, hydrazine, dopamine, sunset yellow, flavonoids, caffeine, glucose, L-lactic acid, chrysophanol, etc., by graphene and graphene oxide-based nanomaterials has also been discussed in detail. This fact proved that there is a bright future for the development of portable sensors used in a variety of applications. The present review is focussed on exploring the synthetic methods, characterization and sensor applications of various graphene supported nanomaterials.

We report the synthesis of medicinal plant, Vernonia amygdalina Del. mediated green copper oxide nanoparticles (VeA-CuO NPs). The presence of two absorbance maxima, λmax 1 and λmax 2 at 436 nm and 452 nm, respectively confirms a mixture of biomolecules surface amalgamated CuO NPs with different morphological features. The FT-IR spectra of the plant leaf extract and VeA-CuO confirmed the efficient role of biomolecules as capping and stabilising agents. The XRD patterns of NPs approved high crystallinity of CuO. The purity of the NPs was corroborated by SEM-EDAX analysis. The average particle size of the NPs was found to be 19.68 nm. In addition, the combined TEM, HRTEM and SAED analysis substantiated the presence of CuO with a d-spacing value of 0.2854 nm, which conformed to CuO (111). The antibacterial assay revealed that VeA-CuO NPs were synergistic in their influence versus bacterial strains, S. aureus, E. coli, P. aeruginosa, and E. aerogenes. The uppermost zone of inhibition of 15 mm was observed for E. aerogenes. The bioactive compounds capped around the CuO NPs served the effective role in disrupting the cell wall of bacterial strains. The degradation efficiencies for Indigo carmine (IC) and Malachite green (MG) dyes by NPs were found to be 95% and 91%, respectively. The lowest degradation half-life was recorded to be 16.55 min for MG dye. In addition, the better electrode stability revealed by CV and EIS studies, confirms the multi-functional nature of VeA-CuO NPs, these CuO NPs exhibited multifunctional applications.

The zinc oxide nanoparticles (T-ZnO NPs) were synthesized successfully by the application of leaf, stem and callus extracts of Tabernaemontana heyneana Wall. via the green combustion method. The structural, bonding and morphological features of T. heyneana mediated ZnO NPs (T-ZnO NPs) were explored using XRD (X-ray powder diffraction), UV–Vis (Ultra-violet visible spectroscopy), FESEM-EDS (Field Emission-SEM and energy-dispersive X-ray spectra), DLS (Dynamic light scattering) and FTIR (Fourier transform infrared) techniques. UV–Vis spectra revealed the presence of a band in the region between 370 and 376 nm approving the presence of T-ZnO NPs. XRD, FESEM-EDS, TEM and DLS analysis confirmed the formation of nanosized, spherical shaped, highly stable and pure crystalline wurtzite T-ZnO NPs. FTIR spectra revealed the presence of most probable phytochemicals from plant extracts involved in the processes of reduction and stabilization of T-ZnO NPs. The T-ZnO NPs could effectively inhibit the activity of DPPH (1, 1-Diphenyl-2-picrylhydrazyl) radical (IC50 value between 467.7 and 752.3 µg/ml) exhibiting potent radical scavenging activity. The T-ZnO NPs exhibited strong anti-inflammatory (membrane stabilization) activity. The antidiabetic potential of T-ZnO NPs was assessed and found to exhibit excellent α-glucosidase (IC 50 at 16.3 µg/ml) and α-amylase (IC 50 at 42.3 µg/ml) activity. The cytotoxic effect of T-ZnO NPs was investigated against A549 cell line (human lung cancer) by MTT assay which showed dose dependent response. IC50 values were found to be in the range of 89.47–185.8 µg/ml demonstrating their higher cytotoxic efficacy. AO/EB staining indicated the presence of early apoptotic cells. The percentage degradation of carcinogenic methylene blue dye was studied and an outstanding catalytic activity of 87–100% was recorded by ZnO-NPs within 160 min. Hence, T-ZnO NPs proved to be better candidates for futuristic biomedical and industrial applications.

For the first time, Tb3+ ions were successfully doped into La10Si6O27 by using low temperature initiate solution combustion method. The resulting Tb3+ doped lanthanum nanophosphors (LNPs) were characterized by PXRD, FTIR, TEM and UV-DRS techniques. The PXRD patterns of calcined sample show a pure hexagonal oxy apatite phase. The crystallite size was found to be within a range of 25–40 nm and it is matched with TEM results. The energy band gap (Eg) was found to vary from 5.64 eV to 5.77 eV. The photocatalytic degradation of Disperse Orange (DO) and Fast Blue (FB) dyes by La10Si6O27:Tb3+ was tested under the irradiation of UV light. La10Si6O27: Tb3+ NPs showed enhanced degradation for Disperse orange and Fast blue dyes under UV light. La10Si6O27:Tb3+ (5 mol %) electrode exhibited reversible electrode reaction with low charge transfer resistance and high capacitance value. All the above findings confirm that the synthesized LNPs is a potential candidate for waste water treatment and sensor applications.

In this study, calcium magnesium aluminate (Ca3MgAl10O17) nanomaterials (CMA NMs) have been synthesized via a simple and cost-effective chemical combustion method using urea as a fuel for the first time. The orthorhombic crystal structure of CMA NMs was confirmed during X-ray diffraction analysis. The lattice grain size of CMA was found in the range of 20 to 25 nm. Kubelka–Munk function was utilized to study diffuse reflectance spectra and the band gap of the nanoparticles was determined to be 5.42 eV. HRTEM-SAED analysis revealed that the CMA NMs were nearly spherical in shape with interplanar spacing value of 0.19 nm. Acid orange-88 (AO-88) dye was used as a model dye to study the photocatalytic properties of the NMs under ultraviolet light irradiation. The degradation study on CMA NMs conformed superior AO-88 dye degradation with 92.25% efficiency proving these NMs to be excellent photocatalysts. The EIS measurements revealed the low charge transfer resistance (Rct) and high capacitance (C) values of 35.36 Ω and 2.815 × 10-3 F respectively, for the prepared CMA electrode. For sensor-based applications, dextrose and metal ions like arsenic, lead, mercury and tin were chosen as analytes. The modified carbon paste electrode of CMA NMs exhibited decent charge transfer properties with an efficient dextrose sensing ability in KCl electrolyte and metal sensing ability in alkaline medium. These results corroborated that the CMA NMs can be a promising electrode material for sensing dextrose and few selected metals with high electrode reversibility. The synthesized CMA NMs are expected to offer significant futuristic opportunities towards multifunctional applications for environmental remediation.

By employing a simple hydrothermal process, a new class of ternary alkali metal-based chalcogenide (NaFeS2 (NFS)) has been produced and anchored on to reduced graphene oxide (rGO) sheets for the first time. Transition metal-based chalcogenides (TMC) exhibit limited conductivity because of their semiconducting nature and hence, engineering TMCs with 2D carbonaceous materials yields better catalytic performance. Alkali metal-based chalcogenides and their composites appear to be promising alternatives, whose electrochemical properties haven't been explored much. This work presents a detailed insight into the structure and morphology of the prepared NFS-rGO composite, along with its electrochemical properties. The cyclic voltammetry (CV) response at the NFS-rGO composite electrode for the redox probe K4Fe(CN)6 is better with low peak to peak separation potentials (ΔEp ​= ​99 ​mV) compared to the individual components NFS (ΔEp ​= ​190 ​mV) and GO (∆Ep ​= ​130 ​mV), indicating a better electron transfer kinetics. The NFS-rGO composite electrode displays an enhanced electrocatalytic activity as evidenced by the high electrochemically active surface area (6.09 ​× ​10−2 ​cm2) and the heterogeneous electron transfer rate constant (k0 ​= ​5.4 ​× ​10−2 ​cms−1). In general, the NFS-rGO composite exhibits excellent material as well electrocatalytic properties due to the synergistic effect between NFS and rGO and can further be explored for electrochemical sensing applications as well.

A series of copper (X) doped NiMnFe2O4 (X = 0.1, 0.2, 0.3, 0.4) nanoparticles (NPs) were synthesized using a simple and effective probe sonication method. The obtained NPs were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–visible studies. The photocatalytic degradation activity of Ni0.2CuxMn0.2Fe2O4 (x = 0.1, 0.2, 0.3, 0.4) NPs were evaluated by degrading methylene blue (MB) and Drimarene yellow (DY) dyes under UV light. The removal efficiencies of 70.2% and 43.3% by NPs with X = 0.1 was observed for MB and DY, respectively. While NPs with X = 0.4 displayed removal efficiencies of 98.1% for MB and 28.9% for DY. The effect of dopant concentration and pH on the photocatalytic ability of the NPs was studied in detail. Electrochemical measurements were performed for the NPs using Cyclic voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) using a carbon paste electrode in acidic (0.1 M HCl) and alkaline (0.1 M NaOH) electrolytes. The specific capacitance values for electrodes with X = 0.1 and 0.4 M were calculated as 244.5 and 498.6 F g−1 in 0.1 M HCl; 40.14 and 25.01 F g−1 in 0.1 M NaOH at a scan rate of 10 mV/s, respectively. EIS measurements further confirmed the CV results. The impedance spectrum of electrode with X = 0.4 in 0.1 M HCl displayed a lowered arc with a smaller diameter in the region of high frequency, revealing the low charge transfer resistance (RCt = 5.281 Ω) and high capacitance (C = 1.654 × 10−8 F) of the electrode. The high reversibility of electrodes and remarkable photocatalytic activity makes them favourable for applications in multifunctional fields.

The current work involves the synthesis of a series of Eu3+ (1–11 mol%) doped La10Si6O27 nanophosphors (ELNPs) by solution combustion method using oxalyl dihydrozil (ODH) as a fuel for the first time. The PXRD studies revealed the average crystallite size in the range 15–35 nm for ELNPs. DRS studies revealed the energy gap of Eu3+ (1–11 mol %) doped La10Si6O27 is ~5.4 eV. The Photoluminescence (PL) studies of the ELNPs showed all the characteristic emission of Eu3+ cations and optimal emission intensity was observed for 5 mol % concentration of Eu3+ ions. The excitation maxima detected at 360 nm, 379 nm, 391 nm, 400 nm, 413 nm and 462 nm were conformed to transitions from 7F0→5G3, 5G4, 5L6, 5D4, 5D3 and 5D2 states of Eu3+ ions respectively. The observed intensities of PL transitions clearly indicated great potentiality for the fabrication of blue/near UV-LED excited phosphor for WLEDs. The calculated CIE chromaticity coordinates confirm the red emission and were depicted in the CIE diagram. The paracetamol and penegra materials were effectively sensed by the prepared carbon paste electrode of Eu3+ (3 mol %) doped La10Si6O27 as revealed by cyclic voltammetric and EIS studies. All the above results show that the synthesized ELNPs can be a potential candidate for display and electrochemical sensor applications.

In this study, nickel ferrite nanoparticles (NiFe2O4 NPs) were synthesized via simple and cost effective sonochemical method. X-ray diffraction confirmed the formation of inverse spinel ferrite with face centered cubic structure and the dimensions of the NPs ranged from 9 to 17 nm. Kubelka–Munk function was applied to study diffuse reflectance spectra and the band gap of the NPs was determined as 2.26 eV. Methylene blue (MB) and Drimarene yellow (DY) dyes were used as model dyes to study the photocatalytic properties of NPs under ultraviolet light irradiation. Point of zero charge (pHpzc) has played a significant role in understanding the adsorption of dyes onto the surface of the photocatalyst. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements for NiFe2O4 electrode were performed in 0.1 M HCl and 0.1 M NaOH aqueous electrolytes. The electrode exhibited specific capacitance of 2.084 F g–1 and 0.533 F g–1 in acidic and basic electrolytes, respectively. EIS measurements showed reduction in the charge transfer resistance. Modified carbon paste electrode using NiFe2O4 NPs has sensed Paracetamol in both acidic and alkaline electrolytes. These results indicated that NiFe2O4 is a promising electrode material for sensing paracetamol with high electrode reversibility and is an excellent photocatalyst. Hence, sonochemically synthesized NiFe2O4 NPs are expected to offer significant insight into their multifunctional applications.

Aluminium oxide nano particles (Al2O3 NPs) were synthesized using simple but effective probe sonication method. The structural, photocatalytic, and electrochemical sensor properties of Al2O3 NPs were investigated by powder X-ray Powder Diffraction (PXRD), Scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), UV–vis Spectroscopy, and Electrochemical analyzer potentiostat. The impact of sonication on the physical properties of Al2O3 NPs was elucidated. From the powder X-ray diffraction (PXRD) studies the material exhibited a face centered cubic structure and γ phase with crystallite size in the range from 6 to 16 nm. The semiconductor behavior has been confirmed from the study of energy band gap via diffuse reflectance spectroscopy (DRS). The conductivity of the samples was studied by cyclic voltammetry (CV) and Electrochemical Impedance spectroscopy (EIS) in 0.1 M HCl and 0.1 M NaOH as aqueous electrolytes. The electrode exhibited specific capacitance of 0.866 F g-1 and 0.488 F g-1 at scan rate 10 mV/s in acidic and alkaline electrolytes, respectively. EIS measurements showed reduction in the charge transfer resistance in acidic electrolyte. Modified carbon paste electrode employing γ-Al2O3 NPs has sensed Paracetamol in both acidic and alkaline electrolytes. The electrode displayed high sensitivity for paracetamol detection under varying concentrations. A linear calibration curve for paracetamol detection was obtained with a limit of detection (LOD) 2.3602 × 10−3 mol/L. These results confirm that the γ-Al2O3 NPs are promising electrode material for sensing paracetamol with high electrode reversibility and as an excellent photocatalyst.

Zn2TiO4:Sm3+ (1–9 mol %) nano powders (NPs) were prepared by a facile solution combustion route using oxalyl dihydrazide (ODH) as a fuel. The obtained product was characterized by Powder X-ray diffraction (PXRD), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and UV–Visible studies. Cyclic voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) measurements were performed using a carbon paste electrode. CV results indicated the reversibility of the electrode reaction, whereas EIS measurements revealed a reduction in the charge transfer resistance with increase in the double layer capacitance of the electrode. The prepared electrodes also exhibited high sensitivity for detection of paracetamol. The photocatalytic degradation of Zn2TiO4:Sm3+ on Titan yellow (TY) dye was evaluated under UV light irradiation. The catalyst showed an excellent photocatalytic activity (PCA) for the degradation of TY dye due to reduction of photo generated electron–hole pair recombination, thereby enhancing absorption. The high electrode reversibility and excellent catalytic activity of Zn2TiO4:Sm3+ make it promising for multifunctional applications. Keywords: Zn2TiO4:Sm3+, XPS, Cyclic voltammetry, EIS, Photocatalysis

The preparation, characterization, and application of Nickel oxide (NiO)–Copper oxide (CuO)–Zinc oxide (ZnO) transition nanometal oxides have significantly enhanced their tunable properties for superior multifunctional performances compared with well-known metal oxides. NiO–CuO–ZnO nano transition metal oxides were synthesized by a simple eco-friendly solution combustion method. X-ray diffraction studies revealed distinct phases such as monoclinic, cubic, and hexagonal wurtzite for CuO, NiO, and ZnO, respectively, with NiO having the highest composition. The particle sizes were found to be in the range between 25 and 60 nm, as determined by powder X-ray diffraction. The energy bandgap values were found to be 1.63, 3.4, and 4.2 eV for CuO, ZnO, and NiO, respectively. All metal oxides exhibited a moderate degradation efficiency for AR88 dye. The results of ultraviolet–visible absorption spectra helped identify the bandgap of metal oxides and a suitable wavelength for photocatalytic irradiation. Finally, we concluded that the electrochemical studies revealed that the synthesized materials are well suitable for sensor applications.

In the present work, a modified β-nickel hydroxide (β-Ni(OH)2) electrode material with CuO has been prepared using a co-precipitation method. The structure and property of the modified β-Ni(OH)2 with CuO were characterized by X-ray diffraction (XRD), Fourier Transform infra-red (FT-IR), Raman and thermal gravimetric-differential thermal analysis (TG-DTA) techniques. The results of the FT-IR spectroscopy and TG-DTA indicate that the modified β-Ni(OH)2 electrode materials contain intercalated water molecules and anions. A pasted–type electrode was prepared using nickel hydroxide powder as the main active material on a nickel sheet as a current collector. Cyclic voltammetry (CV) and Electrochemical impedance spectroscopy (EIS) studies were undertaken to assess the electrochemical behavior of pure β-Ni(OH)2 and modified β-Ni(OH)2 electrode with CuO in a 6 M KOH electrolyte. The addition of CuO into β-nickel hydroxide was found to enhance the reversibility of the electrode reaction and also increase the separation of the oxidation current peak of the active material from the oxygen evolution current. The modified nickel hydroxide with CuO was also found to exhibit a higher proton diffusion coefficient and a lower charge transfer resistance. These findings suggest that the modified β-Ni(OH)2 with CuO possesses an enhanced electrochemical response and thus can be recognized as a promising candidate for battery electrode applications.