Conventional Wet Chemical Methods Research Articles

Green Synthesis of Pure Superparamagnetic Fe3O4 Nanoparticles Using Shewanella sp. in a Non-Growth Medium

Conventional wet chemical methods for the synthesis of superparamagnetic magnetite nanoparticles (MNPs) are energy-intensive and environmentally unsustainable. Green synthesis using bacteria is a less-explored approach to MNP production. Large-scale biosynthesis of MNPs has heretofore been conducted using extremophilic bacteria that exhibit low growth rates and/or require strict temperature control. However, a decrease in material and energy costs would make such bioprocesses more sustainable. In this study, Shewanella putrefaciens CN-32, an iron-reducing bacterium, was employed to reduce amorphous iron oxyhydroxide and synthesize MNPs in a non-growth medium at ambient temperature and pressure. The synthesis was conducted using plain saline solution (0.85% NaCl) to avoid impurities in the products. X-ray diffraction and transmission electron microscopy indicated that the reduction products were MNPs with a pseudo-spherical shape and 6 ± 2 nm average size. Magnetometry showed that the particles were superparamagnetic with maximum saturation magnetization of 73.8 emu/g, which is comparable to that obtained via chemical synthesis methods. Using less than a quarter of the raw materials employed in a typical chemical co-precipitation method, we obtained a maximum yield of 3.473 g/L (>5-fold increase). These findings demonstrate that our simple and ecofriendly process can help overcome the current barriers for large-scale synthesis of high-purity magnetic nanopowders.

Different solvents and organic modifiers for the control of crystallographic parameters in nano-crystallite hydroxyapatite for amplification of photocatalytic activity.

In this research, HAp nanocrystals were synthesized using conventional wet chemical precipitation methods using various organic modifiers, including urea, palmitic acid, and naphthalene. Ethanol and isopropyl alcohol (IPA) were used as solvents in this process. Different characterization techniques, namely X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-vis absorption spectroscopy, were employed to ascertain the formation of HAp nanocrystals. Numerous structural parameters, including lattice parameters, unit cell size, volume of the unit cell, specific surface area, degree of crystallinity, dislocation density, macrostrain, and crystallinity index, were assessed using XRD data. The linear straight-line method of Scherrer's equation, Monshi-Scherrer's method, the Williamson-Hall method, the size-strain plot method, the Halder-Wagner method, and Sahadat-Scherrer's model were applied to compute the crystallite size of the synthesized HAp samples. All the synthesized HAp has crystalline structures within the permissible range of 1-150 nm which were estimated from the XRD data using the mentioned models. However, the values for strain (from -3 × 10-4 to 6.4 × 10-3), strain (from -9.599 × 104 to 7 × 1010 N m-2), and energy density (from -11 × 1011 to 2 × 107 J m-3) were also calculated for the synthesized samples. In addition, the optical band gap energy of the synthesized HAp was computed (5.89 to 6.19 eV). The synthesis media have a control on the crystallographic planes, e.g. in the case of the ethanol medium, the (110) plane exhibited significant intensity (which could potentially serve as a driving force for enhancing photocatalytic activity). The use of 100% ethanol HAp yields the most favorable outcome regarding both the degradation percentage (91.79%) and degradation capacity (7%) for the Congo red dye.

Electrochemical synthesis of trimetallic nickel-iron-copper nanoparticles via potential-cycling for high current density anion exchange membrane water-splitting applications

Hydrogen is known for its elevated energy density and environmental compatibility and is a promising alternative to fossil fuels. Alkaline water electrolysis utilizing renewable energy sources has emerged as a means to obtain high-purity hydrogen. Nevertheless, electrocatalysts used in the process are fabricated using conventional wet chemical synthesis methods, such as sol–gel, hydrothermal, or surfactant-assisted approaches, which often necessitate intricate pretreatment procedures and are vulnerable to post-treatment contamination. Therefore, this study introduces a streamlined and environmentally conscious one-step potential-cycling approach to generate a highly efficient trimetallic nickel-iron-copper electrocatalyst in situ on nickel foam. The synthesized material exhibited remarkable performance, requiring a mere 476 mV to drive electrochemical water splitting at 100 mA cm−2 current density in alkaline solution. Furthermore, this material was integrated into an anion exchange membrane water-splitting device and achieved an exceptionally high current density of 1 A cm−2 at a low cell voltage of 2.13 V, outperforming the noble-metal benchmark (2.51 V). Additionally, ex situ characterizations were employed to detect transformations in the active sites during the catalytic process, revealing the structural transformations and providing inspiration for further design of electrocatalysts.

Rapid Detection of Single- and Co-Contaminant Aflatoxins and Fumonisins in Ground Maize Using Hyperspectral Imaging Techniques

Aflatoxins and fumonisins, commonly found in maize and maize-derived products, frequently co-occur and can cause dangerous illness in humans and animals if ingested in large amounts. Efforts are being made to develop suitable analytical methods for screening that can rapidly detect mycotoxins in order to prevent illness through early detection. A method for classifying contaminated maize by applying hyperspectral imaging techniques including reflectance in the visible and near-infrared (VNIR) and short-wave infrared (SWIR) regions, and fluorescence was investigated. Machine learning classification models in combination with different preprocessing methods were applied to screen ground maize samples for naturally occurring aflatoxin and fumonisin as single contaminants and as co-contaminants. Partial least squares–discriminant analysis (PLS-DA) and support vector machine (SVM) with the radial basis function (RBF) kernel were employed as classification models using cut-off values of each mycotoxin. The classification performance of the SVM was better than that of PLS-DA, and the highest classification accuracies for fluorescence, VNIR, and SWIR were 89.1%, 71.7%, and 95.7%, respectively. SWIR imaging with the SVM model resulted in higher classification accuracies compared to the fluorescence and VNIR models, suggesting that as an alternative to conventional wet chemical methods, the hyperspectral SWIR imaging detection model may be the more effective and efficient analytical tool for mycotoxin analysis compared to fluorescence or VNIR imaging models. These methods represent a food safety screening tool capable of rapidly detecting mycotoxins in maize or other food ingredients consumed by animals or humans.

Large-scale production of MXenes as nanoknives for antibacterial application.

Antimicrobial resistance of existing antibacterial agents has become a pressing issue for human health and demands effective antimicrobials beyond conventional antibacterial mechanisms. Two-dimensional (2D) nanomaterials have attracted considerable interest for this purpose. However, obtaining a high yield of 2D nanomaterials with a designed morphology for effective antibacterial activity remains exceptionally challenging. In this study, an efficient one-step mechanical exfoliation (ECO-ME) method has been developed for rapidly preparing Ti3C2 MXenes with a concentration of up to 30 mg mL-1. This synthetic pathway involving mechanical force endows E-Ti3C2 MXene prepared by the ECO-ME method with numerous irregular sharp edges, resulting in a unique nanoknife effect that can successfully disrupt the bacterial cell wall, demonstrating better antibacterial activity than the MXenes prepared by conventional wet chemical etching methods. Overall, this study provides a simple and effective method for preparing MXenes on a large scale, and its antibacterial effects demonstrate great potential for E-Ti3C2 in environmental and biomedical applications.

Investigation of reflectance, fluorescence, and Raman hyperspectral imaging techniques for rapid detection of aflatoxins in ground maize

Aflatoxins, commonly found in corn and corn-derived products, can cause severe illness in animals and humans if consumed in significant amounts. Early detection is critical to preventing illness, but the most sensitive and effective of commonly used screening tools for aflatoxins are expensive and cumbersome methods based on chromatography or imunoassays that require technical expertise to perform. Multiple hyperspectral imaging techniques, including reflectance in the visible and near-infrared (VNIR) region and short-wave infrared (SWIR) region, fluorescence by 365 nm ultraviolet (UV) excitation, and Raman by 785 nm laser excitation, were used for detection of aflatoxin in ground maize. Four classification models based on linear discriminant analysis (LDA), linear support vector machines (LSVM), quadratic discriminant analysis (QDA), and quadratic support vector machines (QSVM) algorithms were developed for classification with each hyperspectral imaging mode. The multivariate classification models in combination with different preprocessing methods were applied for screening of maize samples naturally contaminated with aflatoxin. The classification accuracies for fluorescence with QSVM, VNIR with QSVM, SWIR with LSVM, and Raman with LSVM were 95.7%, 82.6%, 95.7%, and 87.0%, respectively, with no false-negative error at the cutoff of 10 μg/kg. The SWIR and fluorescence models showed slightly higher performance accuracies, suggesting that they may be more effective and efficient analytical tools for aflatoxin analysis in maize compared to conventional wet-chemical methods. These methods show promise as inexpensive, and easy-to-use screening tools for food safety, to rapidly detect aflatoxins in maize or other food ingredients intended for animal or human consumption.

Architecture engineering of nanostructured catalyst via layer-by-layer adornment of multiple nanocatalysts on silica nanorod arrays for hydrogenation of nitroarenes

Direct consideration for both, the catalytically active species and the host materials provides highly efficient strategies for the architecture design of nanostructured catalysts. The conventional wet chemical methods have limitations in achieving such unique layer-by-layer design possessing one body framework with many catalyst parts. Herein, an innovative physical method is presented that allows the well-regulated architecture design for an array of functional nanocatalysts as exemplified by layer-by-layer adornment of Pd nanoparticles (NPs) on the highly arrayed silica nanorods. This spatially confined catalyst exhibits excellent efficiency for the hydrogenation of nitroarenes and widely deployed Suzuki cross-coupling reactions; their facile separation from the reaction mixtures is easily accomplished due to the monolithic structure. The generality of this method for the introduction of other metal source has also been demonstrated with Au NPs. This pioneering effort highlights the feasibility of physically controlled architecture design of nanostructured catalysts which may stimulate further studies in the general domain of the heterogeneous catalytic transformations.

Potential food applications of sorghum (Sorghum bicolor) and rapid screening methods of nutritional traits by spectroscopic platforms.

Sorghum is a drought-resistant crop widely spread in tropical regions of the American, African, and Asian continents. Sorghum flour is considered the main alternative for wheat flour, and it exhibits gluten-free nature. Generally, conventional wet chemical methods are used to analyze the nutritional profile of sorghum. Since many sorghum plants are available in breeding grounds, the application of conventional methods has limitations due to high cost and time consumption. Therefore, rapid screening protocols have been introduced as nondestructive alternatives. The current review highlights novel and portable devices that can be used to analyze the nutritional composition, color parameters, and pest resistance. Sorghum is often a traditional food item with minimal processing, and the review elaborates on emerging food applications and feasible food product developments from sorghum. The demand for gluten-free products has been rapidly increasing in developed countries. In order to develop food products according to market requirements, it is necessary to screen high-quality sorghum plants. Rapid analysis techniques effectively select the best sorghum types, and the novel tools have outperformed existing conventional methods.

Continuous-flow rapid synthesis of wavelength-tunable luminescent lanthanide metal-organic framework nanorods by a microfluidic reactor

Lanthanide metal-organic frameworks (Ln-MOFs) have been widely used in fluorescence sensing, bioimaging and light emitting diode due to their excellent optical properties. However, the preparation of Ln-MOFs is energy and time-consuming due to the constraints of the conventional wet chemical methods. In this paper, a synthetic strategy for the rapid preparation of Ln-MOFs nanorods with adjustable emission wavelength in a microchannel reactor is proposed. Compared with the wet chemical methods, the efficient mass and heat transfer capability of the microchannel shortens the reaction time from 12 h to 50 min. More importantly, Ln-MOFs nanorods with different emission wavelengths can be easily prepared by adjusting the flow rate of different components of the microchannel, which can be adjusted in real-time according to the preparation needs. The result shows that the Ln-MOFs prepared by microfluidic method is in the shape of nanorods with widely emission wavelength from 470 nm (blue light) to 615 nm (red light). In addition, the fluorescence emission intensity of Ln-MOFs is confirmed to have a wide reversible temperature (30–220 ℃) and is expected to be used for high-precision temperature sensing in the future.

Improved Calibration and Data Processing Procedures of OPUS Optical Sensor for High-Resolution in situ Monitoring of Nitrate in Seawater

Nitrate, an essential nutrient for primary production in natural waters, is optically detectable in the ultraviolet spectral region of 217–240 nm, with no chemical reagents required. Optical nitrate sensors allow monitoring at high temporal and spatial resolutions that are difficult to achieve with traditional approaches involving collection of discrete water samples followed by wet-chemical laboratory analysis. The optical nitrate measurements are however subject to matrix interferences in seawater, including bromide, at the spectral range of interest. Significant progress has been made over the last 10 years in improving data quality for seawater nitrate analysis using the ISUS and SUNA (Seabird Scientific, United States) optical sensors. Standardization of sensor calibration and data processing procedures are important for ensuring comparability of marine nitrate data reported in different studies. Here, we improved the calibration and data processing of the OPUS sensor (TriOS GmbH, Germany), and tested five OPUS sensors simultaneously deployed under identical conditions in the laboratory in terms of inter-sensor similarities and differences. We also improved the sampling interval of the OPUS to 3 s in a continuous mode by a custom-built controller, which facilitates the integration of the sensor into autonomous profiling systems. Real-time, high-resolution, in situ measurements were conducted through (1) underway surface measurements in the southeastern North Sea and (2) depth profiles on a conductivity–temperature–depth frame in the tropical Atlantic Ocean. The nitrate data computed from the optical measurements of the sensor agreed with data from discrete water samples analyzed via conventional wet-chemical methods. This work demonstrates that the OPUS sensor, with improved calibration and data processing procedures, allows in situ quantification of nitrate concentrations in dynamic coastal waters and the open ocean, with an accuracy better than ∼2 μM and short-term precision of 0.4 μM NO3–. The OPUS has a unique depth rating of 6,000 m and is a good and cost-effective nitrate sensor for the research community.

Hollow microspheres of polypyrrole/magnetite/carbon nanotubes by spray-dry as an electromagnetic synergistic microwave absorber

Combining dielectric and magnetic components has been regarded as a promising way to develop functional materials with outstanding microwave absorption (MA) performance. However, it remains a tremendous challenge to assemble multi components into an integrated composite with suitable impedance matching via conventional wet chemical methods. Herein, ternary polypyrrole@Fe3O4/carbon nanotubes (PPy@Fe3O4/CNTs) microspheres with special hollow structure were successfully fabricated via a facile spray-dry method, which can realize rational assembly of magnetic and dielectric components. Hollow PPy@Fe3O4/CNTs spheres simultaneously avoid the agglomeration of magnetic particles while achieve the synergistic absorption. The maximum reflection loss of PPy@Fe3O4/CNTs absorber reached −51.8 dB at 8.8 GHz at the thickness of 2.38 mm. The relationship among components, structure and MA performance was also studied. As MA units, multi-component PPy@Fe3O4/CNTs microspheres effectively combine conductive polymer (PPy), strong magnetic Fe3O4 and high-conductivity CNTs. Thus, the composite gains the advantage of complementation of dielectric, magnetic and conductive loss. Meanwhile, reasonable assembling of different components constructs abundant interfaces which can enhance dielectric polarization and hence improve absorption capacity. The special structure optimizes the distribution of CNTs, helping the composites to achieve better impedance matching. Overall, this work introduces an excellent microwave absorber and gives a new thought of material design.

Rapid high-throughput determination of major components and amino acids in a single peanut kernel based on portable near-infrared spectroscopy combined with chemometrics

The quality traits of peanuts (Arachis hypogaea L.) are fundamental to the whole peanut industry. However, many common analyses require the sample to be brought to the laboratory. Therefore, this research explores the feasibility of portable near-infrared spectroscopy combined with a single detection accessory to analyse the composition of peanuts in a single seed level quantitatively. The single detection accessory was specifically designed for spectral data collection considering the internal and external characteristics of single peanuts. Confocal laser scanning microscopy revealed that the oil body and protein body were randomly distributed at cell of single peanuts. The external characteristics of single peanuts were also determined and considered length (11.32–24.25 mm) and width (7.49–12.25 mm). The chemical compositional data (i.e. fat, sucrose, protein, and 16 amino acids) were determined by conventional wet-chemical methods and showed large variation. Principal component analysis on the compositional data showed that peanuts with higher fat contents usually have higher hydrophobic amino acids contents, lower sucrose contents, and lower protein contents. The composition prediction models of single peanuts were estimated using partial least squares regression models that were integrated with different spectral pre-treatments and validated by external sets. The results showed that the prediction models have good performance with a correlation coefficient above 0.88 (calibration) and 0.83 (prediction) and a residual prediction deviation above 1.5 except for a few indicators. Overall, the portable near-infrared spectroscopy offered reliable methods to assess the major components and amino acids quantitatively in a single peanut, which will improve the raw material quality in the peanut industry through the simultaneous and short-term determination of multiple indicators.

Combining Laser-Induced Breakdown Spectroscopy (LIBS) and Visible Near-Infrared Spectroscopy (Vis-NIRS) for Soil Phosphorus Determination.

Conventional wet chemical methods for the determination of soil phosphorus (P) pools, relevant for environmental and agronomic purposes, are labor-intensive. Therefore, alternative techniques are needed, and a combination of the spectroscopic techniques—in this case, laser-induced breakdown spectroscopy (LIBS)—and visible near-infrared spectroscopy (vis-NIRS) could be relevant. We aimed at exploring LIBS, vis-NIRS and their combination for soil P estimation. We analyzed 147 Danish agricultural soils with LIBS and vis-NIRS. As reference measurements, we analyzed water-extractable P (Pwater), Olsen P (Polsen), oxalate-extractable P (Pox) and total P (TP) by conventional wet chemical protocols, as proxies for respectively leachable, plant-available, adsorbed inorganic P, and TP in soil. Partial least squares regression (PLSR) models combined with interval partial least squares (iPLS) and competitive adaptive reweighted sampling (CARS) variable selection methods were tested, and the relevant wavelengths for soil P determination were identified. LIBS exhibited better results compared to vis-NIRS for all P models, except for Pwater, for which results were comparable. Model performance for both the LIBS and vis-NIRS techniques as well as the combined LIBS-vis-NIR approach was significantly improved when variable selection was applied. CARS performed better than iPLS in almost all cases. Combined LIBS and vis-NIRS models with variable selection showed the best results for all four P pools, except for Pox where the results were comparable to using the LIBS model with CARS. Merging LIBS and vis-NIRS with variable selection showed potential for improving soil P determinations, but larger and independent validation datasets should be tested in future studies.

Eco-friendly preparation of superhydrophobic copper surfaces for oil/water separation

Copper surfaces decorated with micro- and nanostructures can be applied to self-cleaning superhydrophobic surfaces, energy devices and pollution remediation. Wet chemical etching is the classical strategy to grow micro- and nanostructures on copper surfaces. However, such processes usually produce hazardous chemical waste. Here, we present a one-step, eco-friendly and solvent-less alternative to conventional wet chemical methods. Our method involves the use of volatile compounds released from yolk and egg white of boiled chicken eggs as green oxidants for the growth of micro- and nanostructures on the copper surface. After treatment with egg components, copper substrates were modified with stearic acid to make them superhydrophobic. Stearic acid-coated substrates had a contact angle of about 150°, thus confirming their superhydrophobicity. Similar to copper sheets, superhydrophobic copper meshes were also prepared and used for the selective removal of oil from oil/water mixture. Results show that our method produces a wide range of shapes including hollow and solid spheres, nanoflakes, nanoneedles and dome shapes. We found that H2S, the major volatile compound emitted by eggs, is mainly responsible for the growth of microstructures. Therefore, our method can be used both to capture H2S and to design specific surfaces. The mesh exhibited excellent separation efficiency, more than 95% for the organic solvents. A key advantage of our method is that it can be performed also using waste and expired eggs.

Preparation and characterization of superparamagnetic magnetite (Fe3O4) nanoparticles: A short review

Magnetic magnetite (Fe3O4) nanoparticles have attracted a great deal of attention in both fundamental research and practical applications over the past decades. Down to the nanoscale, superparamagnetic Fe3O4 nanoparticles with only a single magnetic domain exhibit high magnetic susceptibility, which provides a stronger and faster magnetic response. Their superparamagnetic properties together with other intrinsic properties such as low toxicity, high surface area-to-volume ratio and simple separation methodology, making them ideal for environmental remediation, biomedical, and agricultural applications. This review discusses three conventional wet chemical methods, including chemical co-precipitation, sol-gel synthesis and thermal decomposition for the preparation of superparamagnetic Fe3O4 nanoparticles with controlled size and magnetic properties. Nowadays, with the growing research interest in Fe3O4 nanoparticles, there is a great amount of researches reported on efficient routes to prepare size-controlled magnetic nanoparticles. Thus, this review is designed to report the recent information from synthesis to the characterization of Fe3O4 nanoparticles as well as the discussion of future perspective in this research area.

Controllable Fabrication of Au Nanocups by Confined-Space Thermal Dewetting for OCT Imaging.

Here, this study reports a novel confined-space thermal dewetting strategy for the fabrication of Au nanocups with tunable diameter, height, and size of cup opening. The nanocup morphology is defined by the cup-shaped void space created by a yolk-shell silica template that spontaneously takes an eccentric configuration during annealing. Thermal dewetting of Au, which is sandwiched between the yolk and shell, leads to the desired nanocup morphology. With strong scattering in near infrared, the Au nanocups exhibit superior efficiency as contrast agents for spectral-domain optical coherence tomography imaging. This confined-space thermal dewetting strategy is scalable and general, and can be potentially extended to the synthesis of novel anisotropic nanostructures of various compositions that are difficult to produce by conventional wet chemical or physical methods, thus opening up opportunities for many new applications.

Plasma Oxidation of Liquid Precursors

Several grand challenges in energy storage and conversion involve the discovery functional materials which many agree will be multi-element solid solution of metal oxides. The conventional wet chemical methods for synthesis of multi-metal oxide often require time-consuming high pressure and temperature processes, and so the challenge is to develop rapid and scalable techniques with precise compositional control. This presentation will discuss the concept of plasma oxidation of liquid precursors for making mixed metal oxides with compositional control and rapid time scales. The concept is demonstrated with binary, ternary and quaternary metal oxide with control over entire composition range using metal precursor solutions.1 For the ternary system, the results show the selective formation of metastable spinel solid solution phases with compositions over the entire range by tuning the metal precursor composition. The concept of plasma oxidation of liquid precursors is investigated to produce a number of materials systems for electrocatalysts, lithium ion batteries and heterogeneous catalysts. For example, in terms of oxygen evolution reaction, ternary alloys involving manganese doped nickel ferrite nanoparticles, NiMnzFe2-zO4 (01), exhibited considerable electrocatalytic activity achieving an overpotential of 0.39V at a benchmarking current density of 10 mAcm-2 for low manganese content at z = 0.2.1 Lithiated NMC compounds exhibit about 220 mAh/g capacity after 50 cycles. Acknowledgements The authors acknowledge support from NSF EPSCoR (1355438) and access to facilities at the Conn Center for Renewable Energy Research. Reference B.P. Ajayi, S. Kumari, D. Jaramillo-Cabanzo, J. Spurgeon, J. Jasinski and M.K. Sunkara, “A rapid and scalable method for making mixed metal oxide alloys for enabling accelerated materials discovery”, J. of Materials Research, DOI: http://dx.doi.org/10.1557/jmr.2016.9231 (11), 1596-1607(2016)

Iodine Pentoxide Nano‐rods for High Density Energetic Materials

AbstractThe iodine pentoxide is one of the most advanced oxidizers for nanostructured energetic formulations among the thermites due to the highest energy release per volume 25.7 kJ cm−3. The size and shape of iodine pentoxide particles have a strong impact on the pressurization rates during the reaction. Although micro‐sized iodine pentoxide particles are commercially available, nano‐sized particles, which are desired for various nano‐energetic applications, are not available on the market. Conventional wet chemical methods are unable to produce iodine pentoxide nanoparticles due to high solubility in water. In this study, we demonstrate fabrication of iodine pentoxide nano‐rods by high energy mechanical treatment of micro‐sized I2O5 particles. Tuning the energy dose in high‐energy ball milling is allowing to produce I2O5 nano‐rods with diameter of 50–100 nm and length of 300–600 nm. The produced nano‐rods exhibited 10 % smaller decomposition energy compared to the precursor of micro particles. The experiments showed that the nano‐energetic materials prepared with nano‐sized I2O5 rods have pressure discharge value of 43.4 MPa g−1 which is two times higher than using commercial iodine pentoxide particles.

Comparison measurements of tar content in gasification systems between an online method and the tar protocol

One of the major obstacles for the application of biomass gasification systems is the relatively high tar content of the producer gas that can inhibit its use in engines or turbines or in further processes like methanation or conversion to other secondary fuels or chemicals. Moreover, tars are difficult to define and also because of the different attempts to do so remains the determination of its content challenging. Nowadays conventional wet chemical and other standard methods for the determination of tars are very time consuming and do not allow continuous online monitoring of the gas quality. Furthermore, the execution by different users can affect the results. One approach to avoid these disadvantages is an automatic system that monitors the tar concentration in the producer gas online during the gasification process.Such an automatic system was developed at IFK in the past with the goal of commercialization and moreover better comparability of the results from tar measuring. To show its accuracy and advantages over standard methods, comparative measurements with the standard method DIN CEN/TS 15439 at an electrically heated lab scale gasifier at different settings have been performed at IFK over several hours. Then, the results of both measurement techniques were compared to each other. The results show a stable operation of the gasifier and therefore also the tar production and its fast detection with the online system. Furthermore, the comparison of the results from both measurement techniques shows good agreement. A satisfying validation of the online method could be conducted.

Atmospheric Plasma Jet Oxidation of Solution Based Precursors for Enabling Material Discovery

Paramount to the global action plan on climate change is the renewable energy technology that drives carbon neutrality goal, and vital in this pursuit is the addressing of material challenges currently facing this technology. To properly address this issue, a synthesis technique capable of accelerating the discovery of materials for various energy conversion and storage applications needs to be developed. Here we present a technique that allows rapid and controlled synthesis of mixed metal oxide particles using plasma oxidation of liquid droplets containing mixed metal precursors1. The conventional wet chemical methods for synthesis of multimetal oxide solid solutions often require time-consuming high pressure and temperature processes, and so the challenge is to develop rapid and scalable techniques with precise compositional control. The concept is demonstrated by synthesizing binary and ternary transition metal oxide solid solutions with control over entire composition range using metal precursor solution droplets oxidized using atmospheric oxygen plasma. The results show the selective formation of metastable spinel and the rocksalt solid solution phases with compositions over the entire range by tuning the metal precursor composition. The synthesized manganese doped nickel ferrite nanoparticles, NiMnzFe2−zO4 (0 ≤ z ≤ 1), exhibits considerable electrocatalytic activity toward oxygen evolution reaction, achieving an overpotential of 0.39 V at a benchmarking current density of 10 mA/cm2 for a low manganese content of z = 0.20.