Low Calcination Temperature Research Articles

Hydration, Reactivity and Durability Performance of Low-Grade Calcined Clay-Silica Fume Hybrid Mortar

Low-grade calcined clay, due to its low cost, availability and low temperature calcination, has been gaining attention in recent times as a supplementary cementitious material (SCM) in the manufacture of revolutionary building materials to improve the fresh and hardened properties of concrete. Silica fume, on the other hand, has been used, over the years, to improve the performance of concrete due to its reduced porosity and improved transition zone quality. In spite of the individual contribution of these two pozzolans to the strength and durability of concrete, there is a knowledge gap in the properties of ternary blended mixes utilizing calcined clay and silica fume. In this study, the synergistic effect of calcined clay and silica fume on the fresh and hardened properties of cementitious mortar have been investigated. The two pozzolans were used to partially substitute Portland cement to form a ternary blended composite binder having, at a maximum, a replacement of 30% by weight and a varying content of calcined clay and silica fume. The influence of the binary and ternary blended mixes on hydration, pozzolanic reactivity and the mechanical and durability properties of mortar was studied. From the results, partial replacement of cement with 30% calcined clay and silica fume caused significant reductions in the portlandite content of the two hydrated pastes at all curing ages. Drying shrinkage was found to be less severe in the control mortar than the blended cement mixes. Compared to the blended cement specimens, the control suffered the most weight (13.3%) and strength (10%) losses, as indicated by the sulphate resistance test.

Anion/cation-induced strong electronic polarization of N,Fe-CoS2 electrocatalyst to boost efficient oxygen evolution

Designing and developing the high activity and long-term durability electrocatalysts for oxygen evolution reaction (OER) has primary significance for breaking the bottleneck of water electrolysis. Herein, an anion/cation-codoped CoS2 based electrocatalyst, N,Fe-CoS2, for the efficient OER was constructed via two-step electrodeposition and low-temperature calcination. The anion and cation optimized significantly the surface electronic structure of N,Fe-CoS2 and induced synergistically a strong surface electronic polarization along with the generation of abundant Co3+ active sites, which improved considerably the intrinsic catalytic activity. The doping N anion also hindered effectively the catalyst surface oxidation and enhanced the catalytic durability. Benefiting from these, N,Fe-CoS2 exhibited the outstanding OER activity and catalytic durability, and especially at a high current density, acquired its ultra-low OER overpotential of 261 mV at 300 mA∙cm−2 and maintained continuously a stable current density for 80 h without visible attenuation at 100 mA∙cm−2. DFT calculations confirmed the cooperative effect of N anions and Fe cations on improving catalytic activity and unveiled that Fe cations in N,Fe-CoS2 acted a key role in modulating electron densities instead of acting as catalytic sites. This work has an important implication for realizing the synergistic regulation of electron densities of catalytic materials by anions and cations.

Lead‐Induced Microstrain in Synthesis and Manipulation of Porous Pyrochlore for Boosting Oxygen Evolution Reaction

AbstractPyrochlore ruthenates are highlighted as candidates to replace iridium oxide as oxygen evolution reaction (OER) electrocatalyst, but their designable geometric configurations and composition modulations are hampered by the high‐temperature (≈1100 °C) and long‐time calcination (more than 12 h), which further decreases the technical and economic feasibility. In this work, an energy‐ and time‐saving approach is proposed to prepare pyrochlore yttrium ruthenate at a much lower calcination temperature (600 °C) and shorter calcination time (6 h) just by inducing A‐site substitutions of lead ions (YPRO). The local microstrain derived from Pb provides the surficial compression and extra driving force to overcome the strain energy of phase‐transition resistances and the obtained low‐temperature YPRO exhibits enriched pores, deficient geometries, shortened Ru─O bond, and enlarged Ru─O─Ru bond angle, which further modify the electronic structure, involving of the rearranged band alignment and the eliminated bandgap. The regulated morphologic, geometric, and electronic structures in YPRO synergically boost the electrocatalytic OER performance (4.8‐fold and 30.0‐fold enhancements compared with pyrochlore yttrium ruthenate and commercial iridium dioxide (IrO2), respectively) in universal pH conditions. This substitution‐induced strain engineering on phase transition should also be effective for other high‐temperature materials and trigger their diverse intriguing properties.

Magnetically recoverable copper ferrite for catalytic ozonation of surfactant-containing simulated laundry wastewater

Laundry detergent wastewater is a valuable renewable resource released in vast quantities that can be reused to alleviate water shortage issues. The primary contaminant found in laundry wastewater, which is the surfactant has harmful impacts on the ecosystem, resulting in the eutrophication of lakes and rivers. This study examines the effectiveness of catalytic ozonation treatment using a magnetically recoverable copper ferrite to treat surfactant-containing laundry wastewater. A magnetically recoverable copper ferrite was successfully prepared using a modified sol-gel method for the remediation of detergent wastewater. The modified sol-gel method uses a low calcination temperature (350 °C) synthesis process to prepare spinel-structured copper ferrite. The physicochemical properties of the prepared copper ferrite were evaluated using XRD, FT-IR, XPS, FESEM, BET, and VSM analyses. Various process parameters such as initial concentration, solution pH, catalyst dosage, and ozone dosage were investigated to reveal the ozone activation capability and catalytic mechanism. The surfactant degradation performance in catalytic ozonation was compared with the non-catalytic ozonation, respectively. Results indicated that the copper ferrite exhibited excellent ozone activation ability, with 98.4% of surfactant degradation at an initial concentration of 10 ppm, a reaction time of 30 min, a catalyst dosage of 0.2 g/L, an initial pH of 7 and an ozone dosage of 3.68 mg/min. The chemical oxygen demand (COD) elimination rate at this setting was 79.5% compared to 26.7% for non-catalytic ozonation. The biochemical oxygen demand (BOD) removal percentages for ozonation and catalytic ozonation were 33.3% and 93.3%, respectively. Simple economical assessment using electrical energy per order (EE/O) showed that low electrical energy was consumed by the catalytic ozonation (60.31 kWhm−3order−1) compared to the ozonation process (381.68 kWhm−3order−1). The copper ferrite can be quickly recovered from the treated water by applying an external magnet, enabling catalyst reuse and easy collection of treated water. Several limitations restrict its application, including metal leaching and catalyst agglomeration. This is the first application of copper ferrite-catalysed ozonation for the remediation of laundry effluent-containing surfactants. These findings showed a vast application potential of catalytic ozonation using copper ferrite for surfactant-containing laundry wastewater treatment.

The Role of Calcination Temperature in the Self-cleaning Functionality of Urea-Doped TiO2 Prepared through In Situ Heat-Assisted Sol–Gel Synthesis

In this study, urea-doped titanium dioxide (urea-TiO2) nanoparticles were synthesized through an in situ heat-assisted sol–gel technique using titanium (IV) isopropoxide as the precursor for titanium dioxide and urea as a nitrogen source. The nanoparticles were calcined at 300, 500, and 700 °C to study the effect of the calcination temperature on their function as self-cleaning material. The nanoparticles were characterized using a scanning electron microscope and a transmission electron microscope for morphology, X-ray diffraction, Raman spectroscopy, and Fourier transformed infrared spectroscopy for structure, UV–Vis, and photoluminescence spectroscopy for optical analysis. The self-cleaning study was carried out by letting samples degrade methylene blue and Rhodamine-B under UV irradiation. The morphological analysis reveals particle size distribution with more disparity at higher calcination temperatures. At lower calcination temperatures, the dopant caused high clustering of particles, keeping them linked together in muddy form and layers. Structural analysis showed that the particles were nanostructured with average crystallite sizes ranging from 2.35 to 16.13 nm and phase transformation from anatase to rutile after calcining at 700 °C. The nitrogen presence created a lattice disorder in the TiO2 structure, and the impact of higher calcination temperature on the nanoparticles further shifted the band toward a higher wavenumber under FTIR analysis. The optical bandgap reduced from 3.29 eV at 300 °C to 3.09 eV at 700 °C. The determined values of the rate constant from the photodegradation test showed that the highest rate was obtained at 700 °C, indicating enhanced self-cleaning functionality with an increase in calcination temperature of urea-TiO2.

Distinguishable Recycling and Photodegradation Processes of Real Industrial Effluents and Blue Dianix Dye in the Presence of Different TQDs Size

Three titanium dioxide quantum dots (TQDs) samples were successfully synthesized at low calcination temperatures via a modified precipitation method at T1 = 330, T2 = 360, and T3 = 400 °C. The synthesized TQDs samples were characterized by: XRD, FE-SEM, HRTEM, and EDX to analyze the crystallinity, purity, and existence of asymmetric circle forms for the TQDs catalysts. Also, the surface area, band gap energy, and crystallite size at different calcination temperatures are 322.32 m2/g, 3.20 eV, and 4.9 nm at 300 °C, 292.39 m2/g, 3.14 eV, and 5.4 nm at 360 °C, and 254.66 m2/g, 3.07 eV, and 6.2 nm at 400 °C, respectively. A xenon photoreactor (70 W/cm2) was used to evaluate the photodegradation process of Blue Dianix dye and sunlight for real industrial effluent treatment. The photocatalytic activity decreases as the crystallite size increases in the TQD samples. Photocatalytic activity of TQDs due to their distinguishable crystalline domain size of less than 10 nm and their high surface area. The photodegradation rate of real industrial effluents was evaluated according to the COD limits permitted by Egyptian environmental law. Also, TOC and COD analyses evaluated 12 recycled samples of TQDs.

Defect‐induced Synthesis of Highly Dispersed Hydroxyapatite‐Supported Vanadium Oxide for the Oxidative Dehydrogenation of Cyclohexane

AbstractHydroxyapatite (HAP) contains abundant defect sites and easily releases hydroxyl groups to produce new vacancies under calcination at high temperature. The highly dispersed VOx/HAP catalyst was prepared by an impregnation method using these defects as inducement. VOx species with different structures were analysed by XRD, XPS, H2‐TPR, Raman and UV–vis spectroscopy. At low calcination temperatures (500 °C and 600 °C), the V species are mainly V2O5 crystals. At high calcination temperatures (above 700 °C), VOx on the HAP surface fills these defect sites and strongly interacts with HAP to form Ca−O−V or P−O−V bands. These scattered defects improved the dispersion of V species. These highly dispersed VOx/HAP catalysts were used for oxidative dehydrogenation (ODH) of cyclohexane to cyclohexene. The highly dispersed VOx/HAP catalyst showed a high selectivity for cyclohexene, and the selectivity reached 48.2 % when the conversion of cyclohexane was 13.1 % at 410 °C.

Inducing Circularly Polarized Luminescence by Confined Synthesis of Ultrasmall Chiral Carbon Nanodot Arrays in Pyrene-Based MOF Thin Film.

Combining the features of the host-guest system and chirality is an efficient strategy to achieve circularly polarized luminescence (CPL). Herein, well-defined chiral carbon nanodot (chirCND) arrays were confined-synthesized by low-temperature calcination of a chiral amino acid loaded metal-organic framework (MOF) to induce high CPL. An achiral porous pyrene-based MOF NU-1000 thin film as the host template was prepared by a liquid-phase epitaxial layer-by-layer fashion, and chiral amino acids as the carbon sources could be confined in the porous MOF and carbonized to homogeneous and ultrasmall chirCND arrays, resulting in a chirCNDs@NU-1000 thin film (l-CNDsx@NU-1000; x = l-cysteine (cys), l-serine, l-histidine, l-glutamic acid, and l-pyroglutamic acid). The results show the pristine chirCNDs by directly carbonizing chiral amino acids hardly endow them with a CPL property. By contrast, benefiting from the arrayed confinement and coordination interaction between chirCNDs and NU-1000, the chirality transfer on the excited state of chirCNDs@NU-1000 is enabled, leading to strong CPL performance (a high luminescence dissymmetry factor glum of l-CNDscys@NU-1000 thin film reached 1.74 × 10-2). This study of chirCNDs encapsulated in fluorescent MOF thin films provides a strategy for developing uniform chiral carbon nanoarrays and offers chiral host-guest thin-film materials for optical applications.

Simultaneous degradation of binary fluoroquinolone antibiotics by B and N in-situ self-doped guar gum hydrogel

Using guar gum (GG) as the raw material and borax (B) as the cross-linker, zeolitic imidazolate framework-8 (ZIF-8) was in-situ loaded into the 3D network of GG hydrogel, forming a highly efficient catalytic material GG-B-ZIF-8 combined with a subsequent low-temperature calcination process. In GG-B-ZIF-8 activated peroxymonosulfate (PMS) system, binary norfloxacin (NOR) and ciprofloxacin (CIP) could be removed simultaneously, with the degradation efficiency of >99.9% within 1 h. This system was adaptable to a wide pH range of 3.0–9.0, and was also highly resistant to 5–20 mM Cl− and 10–40 mg/L humic acid. The degradation process was dominated by free radical O2•-, non-radical 1O2 and electron transfer, with eleven degradation products identified for NOR and nine for CIP via eight possible degradation pathways. Finally, the potential eco-toxicity of NOR, CIP and degradation intermediates was evaluated using the ECOSAR method.

Bioinspired fabrication of zinc hydroxide-based nanostructure from lignocellulosic biomass Litchi chinensis leaves and its efficacy evaluation on antibacterial, antioxidant, and anticancer activity

Zinc-based nanostructures are known for their numerous potential biomedical applications. In this context, the biosynthesis of nanostructures using plant extracts has become a more sustainable and promising alternative to effectively replace conventional chemical methods while avoiding their toxic impact. In this study, following a low-temperature calcination process, a green synthesis of Zn-hydroxide-based nanostructure has been performed using an aqueous extract derived from the leaves of Litchi chinensis, which is employed as a lignocellulose waste biomass known to possess a variety of phytocompounds. The biogenic preparation of Zn-hydroxide based nanostructures is enabled by bioactive compounds present in the leaf extract, which act as reducing and capping agents. In order to evaluate its physicochemical characteristics, the produced Zn-hydroxide-based nanostructure has been subjected to several characterization techniques. Further, the multifunctional properties of the prepared Zn-hydroxide-based nanostructure have been evaluated for antioxidant, antimicrobial, and anticancer activity. The prepared nanostructure showed antibacterial efficacy against Bacillus subtilis and demonstrated its anti-biofilm activity as evaluated through the Congo red method. In addition, the antioxidant activity of the prepared nanostructure has been found to be dose-dependent, wherein 91.52 % scavenging activity could be recorded at 200 μg/ml, with an IC50 value of 45.22 μg/ml, indicating the prepared nanostructure has a high radical scavenging activity. Besides, the in vitro cytotoxicity investigation against HepG2 cell lines explored that the as-prepared nanostructure exhibited a higher cytotoxic effect and 73.21 % cell inhibition could be noticed at 25.6 μg/ml with an IC50 of 2.58 μg/ml. On the contrary, it was found to be significantly lower in the case of HEK-293 cell lines, wherein ~47.64 % inhibition could be noticed at the same concentration. These findings might be further extended to develop unique biologically derived nanostructures that can be extensively evaluated for various biomedical purposes.

Magnetic and Terahertz–Infrared Properties of Nanodispersed Hexaferrite SrxBa(1−x)Fe12O19 Solid Solutions

Hexagonal ferrites with the formula SrxBa(1−x)Fe12O19 (x = 0; 0.3; 0.5; 0.7; and 1) were prepared using the citrate method. The main feature of this synthesis is a relatively low calcination temperature of 700 °C. An X-ray diffraction study revealed a single-phase material. According to SEM, the particles were 50−70 nm in diameter. The Curie temperature of the samples that were determined using the DSC method varied in a very narrow range of 455−459 °C. Analysis of the magnetic hysteresis loops obtained at 300 K and 50 K indicated all samples as magnetically hard materials in a single-domain state. The maximal magnetic characteristics encompass strontium hexaferrite. The terahertz spectra of complex dielectric permittivity and the spectra of infrared reflectivity were measured at room temperature in the range of 6–7000 cm−1. The obtained broad-band spectra of the real and imaginary parts of permittivity reveal significant changes associated with structural distortions of the (Sr,Ba)O12 anti-cuboctahedron caused by the substitution of Ba2+ with Sr2+ in the same crystallographic positions.

Fe2O3/carbon derived from peanut shell hybrid as an advanced anode for high performance lithium ion batteries

Carbon materials derived from biomass behave sustainability, easy availability, low cost and environmentally benign. And Fe2O3 are considered as promising anodes for high-performance Li-ion batteries (LIBs) because of their rich electrochemical properties, higher theoretical capacity (1007 mAh g−1), non-toxicity, high corrosion resistance and safety. However, the high irreversible capacity loss and poor cycling stability of Fe2O3 hinders its commercial applications in LIBs. In this work, we have developed a Fe2O3@C derived from peanut shell composite by two-step hydrothermal method and low-temperature calcination with the assistance of Fe(NO3)3. As an anode for LIBs, the Fe2O3@C composite an excellent electrochemical performance in term of the specific capacity of 1000.8 mAh g−1 at 200 mA g−1 after 100 cycles, and high rate capability of 573.5 mAh g−1 even at 1 A g−1 after 200 cycles. This enhancement could be attributed to the porous carbon matrix combined with Fe2O3 nanoparticles which could increase contact area between electrolyte and active materials, improve conductivity, and accommodate the volume variations via additional void space during cycling. This work may be provide a new approach to improve anode materials using carbon derived-from biomass with larger reversible capacity and long cycle life in LIBs.

Synthesis of ZnO-Al:TiO<sub>2 </sub>Materials and their Characterization as Photocatalyst Compounds

Photocatalyst activity relates to the active surface area between pollutants and catalyst compounds. The insertion of Al atoms as a substantial defect in ZnO structures can reduce the particle size thus the active surface area increases. Another way to raise the photocatalytic activity of ZnO is by combination with other oxide materials such as TiO2 (Titanium dioxide). In this study, the ZnO-Al:TiO2 powder was successfully prepared via the sol-gel method using zinc acetate dihydrate as a precursor, 0.5wt% of aluminum nitrate nonahydrate as a dopant precursor, and TiO2 anatase. In order to understand the role of the combination of these two metal oxides, the concentration ratio of ZnO-Al and TiO2 was varied by 1:1 (ZAT) and 4:1 (ZA4T) under low (150°C) and high (450°C) temperature calcination. Photocatalytic testing was carried out using a 3.2 ppm methylene blue (MB) solution under UV-A lamp irradiation for 120 minutes. The high calcination temperature facilitates the growth of ZnO-Al. Besides that, the different ratio concentrations and calcination temperatures produce different defect states in each sample. The most optimum results in the photocatalytic activity performed by ZnO-Al:TiO2 150°C (ZAT 15) with degradation rate constant (k) of 0.033/min and efficiency of 97% for MB removal. The unexpected zinc vacancies defect is estimated produce at the samples in high-temperature calcination. This defect type can accelerate electron-hole pair recombination. In Addition, samples with high-temperature calcination were considered to have lower hydroxyl/oxygen bonds on the surface thus affecting the photocatalytic performance.

Evaluation of calcined coal slime in binary and ternary ordinary portland cement composites: The role of calcination temperature

Coal slime is a by-product of coal washing plants, which accounts for around 8.3% of total coal production. China generates about 200 million tons of coal slime annually, and most of which can not be utilized efficiently. As a result, the disposal of coal slime leads to serious environmental problems and high costs. To provide a green utilization of coal slime, this study investigated the preparation of binary and ternary cement binder systems by using various calcined coal slime particles. The effects of calcination temperatures (600 °C, 700 °C, 800 °C, and 900 °C) on the evolution of mineral phases, microstructure and morphology of coal slime were addressed and discussed. The feasibility of calcined coal slime in blended cement preparation was tested and evaluated in comparison with calcined coal gangue. The results indicated that kaolinite in coal slime can be effectively transformed into metakaolin at 600 °C. The increase of calcination temperature after 600 °C reduced the reactivity, porosity and water demand of calcined coal slime. 600 °C Calcined coal slime effectively promoted the formation of monosulfate and the monocarboaluminate in binary and ternary cement, respectively, as well as the hydration process. The highest compressive strength of the calcined coal slime blended sample achieved 48.04 MPa, which presented a higher performance than the calcined coal gangue. The organic components in coal slime could be the key to reaching a high reactivity at a low (600 °C) calcination temperature. The calcined coal slime has the potential to be a reactive additive in cement-based materials.

A Simple Preparation of Electrolyte Powder for Stoichiometric Electrolyte in Protonic Ceramic Cells

Among various eco-friendly energy conversion technologies, solid oxide cells (SOCs) exhibit superior energy conversion efficiency and performance owing to the kinetic and thermodynamic advantages. Recently, protonic ceramic cells (PCCs) have begun to attract attention with expectation that the operating temperature of SOCs can be lowered around 500oC, thereby achieving better durability with maintaining higher conversion efficiency. However, the promising proton conducting electrolytes in PCCs are mostly Ba-containing perovskites exhibiting highly refractory property, thus substantially have challenges associated with barium volatilization during high-temperature sintering process. At the same time, Ni-containing transient phases generated at the electrode and supplied to the electrolyte during sintering of electrode/electrolyte bilayer not only facilitate the sintering of electrolyte, but also induce the compositional change owing to the residue thereof. Such off-stoichiometry indeed degrades the electrical properties, and thus most of all reported performance of PCCs could not fully reflect the intrinsic property of electrolytes.Here, we describe a simple but effective strategy to realize the highly conductive electrolyte in PCCs via suppression of barium volatilization as well as minimization of supplied amount of transient phases; a low-temperature calcination process. The electrolyte powder calcined at the relatively lower temperature, which is high enough to react all the precursors without residue, but low enough to suppress the Ba volatilization. The PCCs fabricated using this low-temperature calcined electrolyte powder shows the reduced ohmic resistance, and in turn, enhanced electrochemical performance. While the research on PCCs, up to now, have mainly been focused on processing technique or new materials for the better performance, the result of this study implies that the status of initial electrolyte powder can significantly influence the overall cell characteristics.

Nano-Functionalization of SOFC Electrodes Via Inkjet Printing

Introduction The future of the international accord on mitigating the impact of climate change is linked to the successful commercialisation and implementation of renewable energy technologies. The latter is strongly dependent on finding commercially viable methods for successful dimensional nano-functionalization of the ceramic materials utilized in the fabrication of various energy devices either in energy generation (fuel cells) or storage (batteries, supercapacitors). Inkjet printing digital methods combining scalability and low equipment cost with high-resolution patterning can be a feasible solution for some of the shortcommings of the conventional fabrication technologies. 3D functionalization - Composite solid oxide fuel cells LSCF/CGO cathodes were nano-engineered via “dual” inkjet printing infiltration. The nano-decorated microstructure was found to extend the active three-phase boundary and to promote adsorbtion – dissociation - surface exchange reactions. Composite La0.6Sr0.4Co0.2Fe0.8O3-δ/Ce0.9Gd0.1O1.9 cathodes were subjected to “dual” inkjet printing infiltration of nitrate salt solutions in a single step procedure. After calcination in air at 700 oC the cathodes were decorated with Ce0.9Gd0.1O1.9 and CoxOy nano particles. The effects of as created nano-decoration on the electrochemical activity and the performance stabilty in the intermediate temperature range (500-700 oC) were investigated. The infiltration was found to extend the active three-phase boundary and to promote adsorbtion-dissociation- surface exchange reactions. Electrochemical impedance tests conducted on symmetrical cells showed a reduction in the polarisation resistance of between 1.5 and 7.0 times depending on temperature (500-700 oC). The nano-decoration led to substantially enhanced stability (0.7 Ω•cm2 at 550oC after 100 hours of aging for CGO:CoxOy infiltration). As the composite LSCF/CGO cathodes had already percolating ionic and electronic networks, a low level loading of nanoparticles was sufficient to lead to an efficient short-range extension of the TPB and the density of ORR reaction sites. The sequence of infiltration was shown to influence the efficiency of the ORR promotion. CoxOy:CGO infiltration expanded the available surface area and promoted the catalytical activity towards ORR reaction. The superior effect of CGO:CoxOy infiltration was assigned to the introduction of additional promotion mechanisms (see Fig. 1) resulting in better electrochemical performance at lower temperatures (<650 oC). Both infiltrations suppressed the Sr surface segregation but only CGO:CoxOy infiltrated cathodes showed substantially improved stability after 100 hours of aging. Scaling up - Single step inkjet printing infiltration with doped ceria Ce0.9Ye0.1O1.95 (YDC) and cobalt oxide (CoxOy) precursor inks was performed in order scale-up the modification of the doped ceria interlayer in commercial (50x50x1 mm size) anode supported SOFCs. The penetration of the inks through the mono-phase La0.8Sr0.2Co0.5Fe0.5O3-δ porous cathode to the Gd0.1Ce0.9O2 interlayer was achieved by optimization of inks rheology jetting parameters. The low temperature calcination resulted in densification of the Gd-doped ceria porous interlayer as well as decoration of the cathode scaffold with nano-particles (~ 20-50 nm in size). The I-V testing in pure hydrogen showed maximum power density gain of 20% at 700oC and 97% at 800oC for the infiltrated cells (see Fig. 1). The effect was largely assigned to the improvement in the interfacial Ohmic resistance. The EIS study of the polarization losses of the reference and the infiltrated cells revealed reduction in the activation and concentration polarizations losses at 700oC due to the nano-decoration of the La0.8Sr0.2Co0.5Fe0.5O3-δ scaffold surface. Such effect was not clearly detectable at 800oC where the drop of Ohmic losses was dominant. This work demonstrated that single-step inkjet printing infiltration, a non-disruptive low-cost technique, could produce significant and scalable performance enhancements in commercial SOFCs. Figure 1

Catalysis co-calcination: An available and energy-saving approach to prepare metal/carbon materials with well hydrophobicity and photo-thermal conversion performance

Benefitting from its lightweight, low cost and considerable liquid holding capability, bio-based 3D carbon materials with considerable hydrophobicity have stood out as effective oil-water separators to address oily water problems. However, in order to obtain ideal hydrophobicity, recent approaches such as the thermal-induced sp2-hybridization and nano-texturing construction are energy-consuming and complicated, limiting the large-scale production. Here, through the catalysis co-calcination of transition metals salts (TMSs) and biomass precursor, agriculture solid waste-sugarcane residues were successfully converted to hydrophobic photo-thermal metal/carbon materials (CMs) with lower calcination temperature. Comparing with normal carbonization method, catalysis co-calcination can achieve higher carbonization degree and larger yield with lower consumption energy. The as-prepared Cu-CMs can adsorb 18.49 g/g, 31.33 g/g, 24.45 g/g, 38.25 g/g, and 41.98 g/g of DMF, toluene, methanol, chloroform and carbon tetrachloride, respectively, showing excellent adsorption capability towards organic solvents. Moreover, owing to the synergistic photothermal effect of carbon skeleton and metal remains, the metal/carbon materials can heat the oil efficiently and show better adsorption performance for high-viscous oil. The catalysis co-calcination method is demonstrated as a promising method to produce CMs with unique properties and the metal/carbon materials is also supposed to be an effective wastewater treat materials.

Recovery of ultra-high purity reactive magnesia from reject brine and its comparison with commercial magnesia

CO2 emissions and energy consumption associated with ordinary Portland cement production have increased the urgency for the development of alternative construction materials. Reactive magnesia cement (RMC) has been widely studied in the recent years due to the lower calcination temperature used during its production and its ability to permanently sequester CO2. In addition to the calcination of magnesite, reactive MgO, the main component of RMC, can also be synthesized from reject brine, which is rich in Mg2+. However, the presence of other components such as calcium in reject brine leads to the precipitation of other mineral phases together with Mg(OH)2, thereby reducing the purity of the final product. With the goal of improving the purity and yield of MgO synthesized at the end of this process, this study proposed a selective precipitation approach under a controlled pH. An optimum condition was determined for the synthesis of magnesium oxalate dihydrate with an ultra-high purity of 99.6 % and a high magnesium recovery rate of 94.1 %. Reactive MgO with a specific surface area of 30.2 m2/g was obtained after the calcination of the synthesized magnesium oxalate dihydrate at 700 °C for 2 h, which was higher than some of the commercially available MgO powders.

Efficient removal of para arsanilic acid with Ca-Al-Fe composite: Performances and mechanisms

Para arsanilic acid (p-ASA) as the one of the sources of highly toxic and carcinogenic inorganic arsenic is frequently excreted into the aqueous systems, raising serious environmental hazards and human health risks. Thus, it is compelling to develop techniques that can realize high efficiency of p-ASA removal while being cost effective. Here, a ternary composite material Ca-Al-Fe was designed via facile mechanochemistry and low-temperature calcination on the mixture of inexpensive and readily available Ca(OH)2, C6H9AlO6 and FeC2O4. The results showed that the resulting Ca-Al-Fe composite was capable of achieving a preferable p-ASA adsorption from water with high adsorption capacity (41.23 mg/g), fast kinetic (30 min), long-term stability and reusability on account of the interfacial synergetic effect between ternary composite components. Furthermore, the mechanism investigation demonstrated that, in the preparation stage, CO2 was liberated by the decomposition of FeC2O4, leading to a favorable porous structure and the formation of CaCO3. In the adsorption stage, the hydrolysis of generated CaCO3 enabled the continuous release of OH–, which induced in situ formation of high reactive Fe and Al hydroxides by Al3+ and Fe3+ to adsorb p-ASA by hydrogen bond and coordination interactions. The current work provides a new insight and direction for the development of high-performance metal composite materials.

Facile synthesis of nanostructured bismuth oxide on nickel foam with outstanding electrochemical behavior for supercapacitor application

Utilizing green technology to realize efficient energy storage for supercapacitor is an extremely popular issue at present. Herein, bismuth oxide nanoparticles grown on nickel foam substrates (BN) are successfully synthesized using a facile electrodeposition technique followed by a low temperature calcination process and thereby employed as superior electrodes for high-performance supercapacitors. The influences of electrodeposition time and carbonization temperature on the electrochemical performances of BN samples have been studied. The BN-8–300 electrode is prepared with the optimized conditions of deposition time 8 min and annealing temperature 300 °C which exhibits the largest specific capacities (1223.9 C g−1 at 1 A g−1) as well as a satisfactory cycling performance (86.8% capacity retention at 4 A g−1) after 5000 cycles. Furthermore, the symmetric supercapacitor is fabricated utilizing two identical BN-8–300 electrodes which presents an energy density as high as 86.4 Wh kg−1 at the power density of 497.9 W kg−1 coupled with an outstanding cyclic stability (82.6% of its original capacitance after 5000 cycles). This facile synthetic strategy manifests a great promising application in developing innovative, durable and inexpensive bismuth oxide-based electrodes for energy storage devices.