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Exposure to hydroquinone (HQ) can cause various health hazards and negative impacts on the environment. Therefore, we developed an efficient electrochemical sensor to detect and quantify HQ based on palladium nanoparticles deposited in a porous silicon-polypyrrole-carbon black nanocomposite (Pd@PSi−PPy−C)-fabricated glassy carbon electrode. The structural and morphological characteristics of the newly fabricated Pd@PSi−PPy−C nanocomposite were investigated utilizing FESEM, TEM, EDS, XPS, XRD, and FTIR spectroscopy. The exceptionally higher sensitivity of 3.0156 μAμM−1 cm−2 and a low limit of detection (LOD) of 0.074 μM were achieved for this innovative electrochemical HQ sensor. Applying this novel modified electrode, we could detect wide-ranging HQ (1–450 μM) in neutral pH media. This newly fabricated HQ sensor showed satisfactory outcomes during the real sample investigations. During the analytical investigation, the Pd@PSi−PPy−C/GCE sensor demonstrated excellent reproducibility, repeatability, and stability. Hence, this work can be an effective method in developing a sensitive electrochemical sensor to detect harmful phenol derivatives for the green environment. [ABSTRACT FROM AUTHOR]

Current work describes green synthesis of Fe, Mn (monometallic) and Fe-Mn (bimetallic) nanoparticles using Cannabis sativa leaf extract as stabilizing and capping agent. In order to assess the formation of nanoparticles UV/Vis and FTIR analysis was carried out. In addition, Scanning electron microscopy and XRD studies confirmed synthesis as well as morphology of the nanoparticles. All the nanoparticles were found having particle size 20–80 nm and crystallite 3–20 nm. Photocatalytic activity of synthesized nanoparticles has been evaluated by carrying out degradation of two dyes methyl orange (MO) and Congo red (CR) in the presence of nanocatalysts. Degradation of both the dyes was carried out separately using Fe, Mn and Fe-Mn nanoparticles to compare the efficiency of monometallic with bimetallic nanoparticles. Iron and manganese monometallic particles have completely degraded MO in 18 min and 20 min and CR in 24 min and 18 min respectively. However, due to increased synergistic effect Fe-Mn BNPs completely degraded MO dye in just 12 min and CR in 14 min. In nutshell, this work is actually a step towards the synthesis of bimetallic nanoparticles using a plant extract with improved synergistic photocatalytic activities which impart various properties to the designed nanomaterial. [ABSTRACT FROM AUTHOR]

Pure TiO2 and barium (0.5 wt%) doped TiO2 (Ba/TiO2) nanostructures have been synthesized via facile microwave irradiation method. The pure anatase phase of synthesized photoactive material was confirmed by X-ray diffraction. Ba doping in the TiO2 host structure influenced the optical band gap as confirmed by UV-visible spectroscopy. The optical band gap increased from 3.21 eV for the TiO2 to 3.26 eV for Ba/TiO2. Morphological analysis of synthesized TiO2 and Ba/TiO2 was conducted using scanning electron microscopy. Energy dispersive X-ray spectroscopy confirmed the formation of Ba/TiO2 and no impurities were observed. Electrochemical impedance spectroscopy showed that the charge transfer resistance increased for Ba/TiO2, which reduced dark current creation in a dye-sensitized solar cell. The highest power conversion efficiency (3.24%) was achieved for Ba/TiO2 photoanode compared to 2.1% for a pure TiO2 photoanode-based device. [ABSTRACT FROM AUTHOR]

Copper-silver and cobalt-silver alloy nanoparticles deposited on reduced graphene oxide (CuAg/rGO and CoAg/rGO) were synthesized and examined as electrocatalysts for oxygen reduction reaction (ORR) and hydrogen peroxide reduction reaction (HPRR) in alkaline media. Characterization of the prepared samples was done by transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction analysis (XRD), and scanning electron microscopy with integrated energy-dispersive X-ray spectroscopy (SEM-EDS). CuAg/rGO and CoAg/rGO nanoparticles diameter ranged from 0.4 to 9.2 nm. The Ag loading was ca. 40 wt.% for both electrocatalysts, with that for Cu and Co being 35 and 17 wt.%, respectively. CoAg/rGO electrocatalyst showed a Tafel slope of 109 mV dec−1, significantly lower than that for CuAg/rGO (184 mV dec−1), suggesting faster ORR kinetics. Additionally, a higher diffusion current density was obtained for CoAg/rGO (−2.63 mA cm−2) than for CuAg/rGO (−1.74 mA cm−2). The average value of the number of electrons transferred during ORR was 2.8 for CuAg/rGO and 3.3 for CoAg/rGO electrocatalyst, further confirming the higher ORR activity of the latter. On the other hand, CuAg/rGO showed higher peak current densities (−3.96 mA cm−2) for HPRR compared to those recorded for CoAg/rGO electrocatalyst (−1.96 mA cm−2). [ABSTRACT FROM AUTHOR]

Titanium dioxide nanoparticles play a crucial role in the production of hydrogen gas evolution. Among the four polymorphic phases of TiO2 (anatase, rutile, brookite, and TiO2 (B)), the anatase phase shows good photo activity in catalytic applications. We prepared a single anatasephase of TiO2 nanoparticles usinga facile one-step ionothermal method with the existence of 1-(3,6-dioxa heptane) 3-methyl imidazolium methane sulfonate IL[DOMIMS]. The ionic liquid-based substitution reaction mechanism was utilized for the ionothermal synthesis of TiO2. The anatase phase structure and nanoparticle-like morphology of synthesized TiO2 nanomaterial were confirmed by XRD analysis and TEM studies. The vibrational frequency of the Ti–O–Ti bond at 544 cm−1 was measured usingthe FTIR spectrum, and the UV absorbance of the sample was studied usingthe UV/visible spectra. The prepared TiO2 nanoparticles showed the best results of H2 generation via awater-splitting reaction, liberating 2084 μmol·g−1·h−1 of H2 gas. TiO2 nanoparticles act as a good material for electrochemical applications such as supercapacitors and sensing of dopamine, as well as a better photocatalyst for the degradation of methylene blue. [ABSTRACT FROM AUTHOR]

Herein, we demonstrate the effectiveness of surface-enhanced Raman scattering (SERS) to detect trace concentration of potentially harmful imidacloprid pesticide. To achieve this ultimate objective, a rapid and highly effective methodology for the fabrication of active and stable porous silicon (PSi) plated palladium nanoparticles (PdNPs) SERS substrates by an electrochemical anodization and immersion plating routes was applied. The PSi layers were fabricated by the electrochemical anodization of a silicon wafer in ethanoic fluoride solution, followed by uniformly deposition of PdNPs via a simple immersion plating technique. The structural features and morphology of fabricated frameworks of PSi-Pd NPs have been investigated by field emission scanning electron microscopy (FE-SEM) with energy dispersive X-ray (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) spectra. The PSi substrate demonstrates a meso-porous morphology with good distribution, good pore density and average pore sizes around 20 nm. The SERS performance of Si–Pd NPs and PSi–Pd NPs substrates has been examined taking imidacloprid (an insecticide) as a target analyte. The SERS signal of imidacloprid using PSi–Pd NPs substrate exhibited immense enhancement compared to the Si-Pd NPs substrate. The active substrate revealed excellent detectable performance with a concentration as low as 10–9 M imidacloprid and an enhancement factor (EF) of 1.2 × 105. This large EF is fundamentally ascribed to the combined effect of the electromagnetic improvement and charge transfer mechanisms. Additionally, no aging effect was observed for the present substrates kept in air for two weeks. Striking enhancement in Raman spectral signals obtained with the current PSi–Pd NPs substrates can provide a simple and smooth platform towards the sensitive detection of various target analytes. [ABSTRACT FROM AUTHOR]

Depletion of non-renewable fuel has obliged researchers to seek out sustainable and environmentally friendly alternatives. Membranes have proven to be an effective technique in biofuel production for reaction, purification, and separation, with the ability to use both porous and non-porous membranes. It is demonstrated that a membrane-based sustainable and green production can result in a high degree of process intensification, whereas the recovery and repurposing of catalysts and alcohol are anticipated to increase the process economics. Therefore, in this study sustainable biodiesel was synthesized from inedible seed oil (37 wt%) of Cordia myxa using a membrane reactor. Transesterification was catalyzed by heterogenous nano-catalyst of indium oxide prepared with leaf extract of Boerhavia diffusa. Highest biodiesel yield of 95 wt% was achieved at methanol to oil molar ratio of 7:1, catalyst load 0.8 wt%, temperature 82.5 °C and time 180 min In 2 O 3 nanoparticles exhibited reusability up to five successive transesterification rounds. The production of methyl esters was confirmed using Fourier-transform infrared spectroscopy and Nuclear Magnetic Resonance. The predominant fatty acid methyl ester detected in the biodiesel was 5, 8-octadecenoic acid. Biodiesel fuel qualities were determined to be comparable to worldwide ASTM D-6571 and EN-14214 standards. Finally, it was concluded that membrane technology can result in a highly intensified reaction process while efficient recovery of both nano catalysts and methanol increases the economics of transesterification and lead to sustainable production. [Display omitted] • Waste seed oil of Cordia myxa as a novel and renewable energy source. • Membrane technology as an effective tool for separation and purification. • Synthesis of indium oxide nanoparticles to catalyze transesterification. • Optimum yield of 95 wt % of methyl ester was obtained. • All properties of methyl ester matched well with international standards. [ABSTRACT FROM AUTHOR]

The release of phenolic-contaminated treated palm oil mill effluent (TPOME) poses a severe threat to human and environmental health. In this work, manganese-modified black TiO2 (Mn-B-TiO2) was produced for the photodegradation of high concentrations of total phenolic compounds from TPOME. A modified glycerol-assisted technique was used to synthesize visible-light-sensitive black TiO2 nanoparticles (NPs), which were then calcined at 300 °C for 60 min for conversion to anatase crystalline phase. The black TiO2 was further modified with manganese by utilizing a wet impregnation technique. Visible light absorption, charge carrier separation, and electron–hole pair recombination suppression were all improved when the band structure of TiO2 was tuned by producing Ti3+ defect states. As a result of the enhanced optical and electrical characteristics of black TiO2 NPs, phenolic compounds were removed from TPOME at a rate of 48.17%, which is 2.6 times higher than P25 (18%). When Mn was added to black TiO2 NPs, the Ti ion in the TiO2 lattice was replaced by Mn, causing a large redshift of the optical absorption edges and enhanced photodegradation of phenolic compounds from TPOME. The photodegradation efficiency of phenolic compounds by Mn-B-TiO2 improved to 60.12% from 48.17% at 0.3 wt% Mn doping concentration. The removal efficiency of phenolic compounds from TPOME diminished when Mn doping exceeded the optimum threshold (0.3 wt%). According to the findings, Mn-modified black TiO2 NPs are the most effective, as they combine the advantages of both black TiO2 and Mn doping. [ABSTRACT FROM AUTHOR]

We report a facile synthesis of β-SnWO4 nanoparticles via a microwave heat treatment using SnCl2 and H2WO4 in the presence of tamarind seed powder. An X-ray diffraction analysis confirmed a crystalline nature revealing a cubic structure of β-SnWO4 nanoparticles. The morphological features were visualized using a scanning electron microscope that exhibited homogenously distributed clusters of nanoparticles, which were further confirmed using a transmission electron microscope. The micrographs also displayed some porosity. Energy dispersive X-ray spectroscopy confirmed the elemental contents such as tin, oxygen and tungsten in the same stoichiometric ratio as expected by the respective empirical formula. A high-resolution transmission electron microscope was used to find the d-spacing, which was ultimately used to analyze the structural parameters. The spectrum obtained using Fourier transform infrared spectroscopy illuminated different stretching vibrations. Additionally, a Barrett–Joyner–Halenda analysis was carried out to investigate the N2 adsorption-desorption isotherm as well as to govern the pore size distribution. Cyclic voltammetry measurements were implemented to analyze the ongoing electrode reactions throughout the charge/discharge for the β-SnWO4 nanostructures. The galvanometric charge/discharge curves for β-SnWO4 are also discussed. A high specific capacitance (600 mAhg–1 at 0.1 C) and excellent columbic efficiency (~100%) were achieved. [ABSTRACT FROM AUTHOR]

• Facile hydrothermal synthesis and characterizations of α-MnO 2 nanoparticles. • Utilization of synthesized α-MnO 2 nanoparticles to fabricate ethanol gas sensor. • At temperature of 300 °C and 200 ppm ethanol the gas response was 30.6. • The response and recovery times were 30 s and 40 s, respectively. α-MnO 2 nanoparticles were hydrothermally synthesized and characterized for their various physicochemical properties using different techniques. The average diameter of the nanoparticles was observed to be 70 ± 5 nm along with well-resolved inter-planar spacing of 0.241 nm corresponding to (211) plane for α-MnO 2 crystal phase. Working electrode for ethanol gas sensing fabricated by using α-MnO 2 nanoparticles showed gas response of 30.6 at optimized temperature of 300 °C. The corresponding response and recovery times were 30 s and 40 s, respectively for 200 ppm ethanol at 300 °C. [ABSTRACT FROM AUTHOR]

• A room-temperature formaldehyde sensing material ZnO-ANS-rGO was prepared. • The facile one-pot solution synthesis avoids large energy consumption. • The dipole ANS plays a key role in decreasing working temperature of the sensor. The room temperature formaldehyde (HCHO) sensor has promising application in practical indoor air pollution detection. In this study, we assembled ZnO nanoparticles modified graphene nanosheets with dipoles by a facile solution process to fabricate a room temperature formaldehyde sensing material zinc oxide-(5-aminonaphthalene-1-sulfonic acid)-reduced graphene oxide (ZnO-ANS-rGO). The prepared ZnO-ANS-rGO sensor could detect as low as 5 ppm HCHO at room temperature. The following inverstigation showed that the outstanding gas sensing performances including high gas selectivity and reliable gas sensing reversibility were attributed to the synergism of modification of 5-aminonaphthalene-1-sulfonic acid (ANS) and ZnO nanoparticles. It was concluded that ANS greatly facilitated the charge transfer from compound to formaldehyde molecules so that the detection could be implemented at lower energy barrier. [ABSTRACT FROM AUTHOR]

• Solid-state synthesis of Ag-doped PANI nanocomposites. • Ag-doped PANI nanocomposites based GCE successfully applied for the electrochemical sensing of H 2 O 2 and DA. • CV, DPV, and amperometry techniques confirmed the reduction of H 2 O 2 and the oxidation of DA to DA quinone. • For H 2 O 2 and DA, the detection limits as measured from current-time chronoamperometry were 0.03 µM and 0.12 µM, respectively, from DPV. Polyaniline protected silver nanoparticles (Ag-doped PANI nanocomposites) were synthesized successfully by a solid-state mechano-chemical oxidative polymerization. AgNO 3 acted as a metal precursor as well as an oxidizing agent. The prepared Ag-doped PANI nanocomposites were characterized by various techniques such as TEM, FE-SEM, XRD, FTIR and UV–vis spectroscopy. XRD confirmed the cubic FCC form of the Ag nanoparticles with an average crystal size of ~36.04 nm for the Ag-doped PANI nanocomposites. FE-SEM and TEM analysis of Ag-doped PANI nanocomposites revealed the formation of spherical as well as semi-spherical Ag nanoparticles embedded in the PANI polymer matrix. Cyclic voltammogram revealed excellent electrochemical responses and electrocatalytic behavior of the Ag-doped PANI nanocomposites/GCE for hydrogen peroxide (H 2 O 2) and dopamine (DA). Based on cyclic, amperometric and differential pulse voltammetric analysis, it was found that H 2 O 2 undergoes reduction whereas DA is oxidized at the surface of the modified Ag-doped PANI nanocomposites/GCE. For H 2 O 2 and DA, the detection limits as measured from differential pulse voltammetric analysis were 0.03 µM and 0.12 µM, respectively. Image, graphical abstract [ABSTRACT FROM AUTHOR]