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Solid oxide structure of the cobalt-free composite has been exploited as a new cathode material for IT-SOFCs. The composite model system was synthesized using the metallic oxide material, which was formed by a solid-state reaction technique. The generation of the Sm0.5Sr0.25Ba0.25FeO3-δ (SSBF) model system was carried out during the sintering process. The weight loss and oxygen content were investigated by thermal gravimetric analysis (TG). Meanwhile, X-ray diffraction characterized the structure of the composite and thermal conductivity tested the conductivity properties. The results showed that the structure of the SSBF composite demonstrated the perovskite single phase leading to the structural design. The decomposition and evaporation of the constituent elements of the composite corresponded to weight losses during the constructing process. The oxygen content of the model system was 2.98 after the calcination process. The electrical conductivity value reached 2 S cm-1 at 400 °C and increases to a maximum of 7.5 S cm-1 at 710 °C. The metallic element played to generating the conductive behavior at the low temperature, while the ionic structure acted as elevated temperature. So, mixed ionic and electric conductors (MIEC) were employed comprehensively for creating the conductive properties. Based on the structure and conductivity results, the SSBF composite has a good chance as an alternative cathode material with a perovskite single phase for future TI-SOFCs applications, Твердооксидная структура бескобальтового композита была использована в качестве нового катодного материала для СТ-ТОТЭ. Модельная система композита была синтезирована с использованием металлического оксидного материала, полученного методом твердотельной реакции. Формирование модельной системы Sm0.5Sr0.25Ba0.25FeO3-δ (SSBF) осуществляли в процессе спекания. Потерю веса и содержание кислорода исследовали методом термогравиметрического анализа (ТГ). При этом, с помощью рентгеноструктурного анализа характеризовали структуру композита, свойства проводимости испытывали с помощью теплопроводности. Результаты показали, что структура композита SSBF демонстрирует однофазность перовскита, приводящую к построению структуры. Распад и испарение составляющих элементов композита соответствовали потерям веса в процессе построения структуры. После прокаливания содержание кислорода в модельной системе составило 2,98. Значение электропроводности достигло 2 См см-1 при 400 °C и увеличивается до максимума 7,5 См см-1 при 710 °C. Металлический элемент играл роль проводника при низкой температуре, в то время как ионная структура действовала как повышенная температура. Таким образом, для создания проводящих свойств были комплексно использованы смешанные ионные и электрические проводники (СИЭП). Основываясь на результатах по структуре и проводимости, композит SSBF имеет хорошие шансы в качестве альтернативного катодного материала с однофазным перовскитом для будущих применений СТ-ТОТЭ., Твердооксидну структуру безкобальтового композиту було використано в якості нового катодного матеріалу для СТ-ТОПЕ. Модельна система композиту була синтезована з використанням металевого оксидного матеріалу, отриманого методом твердотільної реакції. Формування модельної системи Sm0.5Sr0.25Ba0.25FeO3-δ (SSBF) здійснювали в процесі спікання. Втрату ваги і вміст кисню досліджували методом термогравіметричного аналізу (ТГ). При цьому, за допомогою рентгеноструктурного аналізу характеризували структуру композиту, властивості провідності випробовували за допомогою теплопровідності. Результати показали, що структура композиту SSBF демонструє однофазність перовськіту, що призводить до побудови структури. Розпад і випаровування складових елементів композиту відповідали втратам ваги в процесі побудови структури. Після прожарювання вміст кисню в модельній системі склав 2,98. Значення електропровідності досягло 2 См см-1 при 400 °C і збільшується до максимуму 7,5 См см-1 при 710 °C. Металевий елемент грав роль провідника при низькій температурі, в той час як іонна структура діяла як підвищена температура. Таким чином, для створення провідних властивостей були комплексно використані змішані іонні та електричні провідники (ЗІЕП). Виходячи з результатів структури та провідності, композит SSBF має хороші шанси в якості альтернативного катодного матеріалу з однофазним перовськітом для майбутніх застосувань СТ-ТОПЕ.

Titanium dioxide (TiO2) has been acknowledged as one of the efficient photocatalysts in the UV region. To extend the photo-absorption region toward visible lights, the TiO2 nanowires enclosed with carbon shells (TiO2@carbon core-shell nanowires) were synthesized by a chemical vapor deposition technique at various temperatures from 650 to 950 °C. The transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses revealed that TiO2 cores and carbon shells are rutile and graphitic structures, respectively. From Raman spectra, the peak intensity of the Eg mode was observed to be redshifted with elevated growth temperatures due to the increase in oxygen vacancies in the TiO2@carbon core-shell nanowires. From X-ray photoelectron spectroscopy (XPS) results, the oxygen vacancies were strongly related to the Ti3+ ions. The UV–visible spectroscopic studies show a possible decrease in photocatalytic energy from 3.1 to 2.7 eV for the TiO2@carbon core-shell nanowires, indicating that the light absorption was enhanced in the visible-light region. The optical absorbance results confirmed the presence of the mid-gap states due to the oxygen vacancies, which are responsible for the visible-light absorption. The photocatalytic activity of the TiO2@carbon core-shell nanowires studied by methylene blue (MB) dye degradation is effective under visible lights.

The main obstacle to solid oxide fuel cells (SOFCs) implementation is the high operating temperature in the range of 800–1,000 °C so that it has an impact on high costs. SOFCs work at high temperatures causing rapid breakdown between layers (anode, electrolyte, and cathode) because they have different thermal expansion. The study focused on reducing the operating temperature in the medium temperature range. SmBa0.5Sr0.5Co2O5+δ (SBSC) oxide was studied as a cathode material for IT-SOFCs based on Ce0.8Sm0.2O1.9 (SDC) electrolyte. The SBSC powder was prepared using the solid-state reaction method with repeated ball-milling and calcining. Alumina grinding balls are used because they have a high hardness to crush and smooth the powder of SOFC material. The specimens were then tested as cathode material for SOFC at intermediate temperature (600–800 °C) using X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), electrochemical, and scanning electron microscopy (SEM) tests. The X-ray powder diffraction (XRD) pattern of SBSC powder can be indexed to a tetragonal space group (P4/mmm). The overall change in mass of the SBSC powder is 8 % at a temperature range of 125–800 °C. A sample of SBSC powder showed a high oxygen content (5+δ) that reached 5.92 and 5.41 at temperatures of 200 °C and 800 °C, respectively. High diffusion levels and increased surface activity of oxygen reduction reactions (ORRs) can be affected by high oxygen content (5+δ). The polarization resistance (Rp) of samples sintered at 1000 °C is 4.02 Ωcm2 at 600 °C, 1.04 Ωcm2 at 700 °C, and 0.42 Ωcm2 at 800 °C. The power density of the SBSC cathode is 336.1, 387.3, and 357.4 mW/cm2 at temperatures of 625 °C, 650 °C, and 675 °C, respectively. The SBSC demonstrates as a prospective cathode material for IT-SOFC, Основным препятствием для внедрения твердооксидных топливных элементов (ТОТЭ) является высокая рабочая температура в диапазоне 800-1000 °С, что сказывается на высоких затратах. ТОТЭ работают при высоких температурах, что вызывает быстрый разрыв между слоями (анод, электролит и катод), поскольку они имеют различное тепловое расширение. Исследование посвящено снижению рабочей температуры в среднем температурном диапазоне. В качестве катодного материала для ПТ-ТОТЭ на основе электролита Ce0.8Sm0.2O1.9 (SDC) был исследован оксид SmBa0.5Sr0.5Co2O5+δ (SBSC). Порошок SBSC получали методом твердофазной реакции с повторным измельчением в шаровой мельнице и прокаливанием. Использовались мелющие шары из оксида алюминия поскольку они обладают высокой твердостью для измельчения и сглаживания порошка материала ТОТЭ. Затем было проведено испытание образцов в качестве катодного материала для ТОТЭ при промежуточной температуре (600-800 °C) с использованием порошковой рентгеновской дифракции (ПРД), термогравиметрического анализа (ТГА), электрохимических испытаний и сканирующей электронной микроскопии (СЭМ). Дифрактограмма порошка SBSC можно индексировать по тетрагональной кристаллографической группе (P4/mmm). Общее изменение массы порошка SBSC составляет 8% в диапазоне температур 125-800 °C. Образец порошка SBSC показал высокое содержание кислорода (5+δ), которое достигало 5,92 и 5,41 при температурах 200 °C и 800 °C соответственно. Высокое содержание кислорода (5+δ) может влиять на высокие уровни диффузии и повышенную поверхностную активность реакций восстановления кислорода (РВК). Поляризационное сопротивление (Rp) образцов, спеченных при 1000 °C, составляет 4,02 Омсм2 при 600 °C, 1,04 Омсм2 при 700 °C и 0,42 Омсм2 при 800 °C. Удельная мощность катода SBSC составляет 336,1, 387,3 и 357,4 МВт/см2 при температуре 625 °С, 650 °С и 675 °С соответственно. SBSC демонстрирует перспективность в качестве катодного материала для ПТ-ТОТЭ, Основною перешкодою для впровадження твердооксидних паливних елементів (ТОПЕ) є висока робоча температура в діапазоні 800–1000 °С, що позначається на високих витратах. ТОПЕ працюють при високих температурах, що викликає швидкий розрив між шарами (анод, електроліт і катод), оскільки вони мають різне теплове розширення. Дослідження присвячено зниженню робочої температури в середньому температурному діапазоні. В якості катодного матеріалу для ПТ-ТОПЕ на основі електроліту Ce0.8Sm0.2O1.9 (SDC) був досліджений оксид SmBa0.5Sr0.5Co2O5+δ (SBSC). Порошок SBSC отримували методом твердофазної реакції з повторним подрібненням в кульовому млині і прожарюванням. Використовувалися мелючі кулі з оксиду алюмінію оскільки вони мають високу твердість для подрібнення і згладжування порошку матеріалу ТОПЕ. Потім було проведено випробування зразків в якості катодного матеріалу для ТОПЕ при проміжній температурі (600–800 °C) з використанням порошкової рентгенівської дифракції (ПРД), термогравіметричного аналізу (ТГА), електрохімічних випробувань і скануючої електронної мікроскопії (СЕМ). Дифрактограму порошку SBSC можна індексувати за тетрагональною кристалографічною групою (P4/mmm). Загальна зміна маси порошку SBSC становить 8 % в діапазоні температур 125–800 °C. Зразок порошку SBSC показав високий вміст кисню (5+δ), що досягав 5,92 і 5,41 при температурах 200 °C і 800 °C відповідно. Високий вміст кисню (5+δ) може впливати на високі рівні дифузії і підвищену поверхневу активність реакцій відновлення кисню (РВК). Поляризаційний опір (Rp) зразків, спечених при 1000 °C, становить 4,02 Омсм2 при 600 °C, 1,04 Омсм2 при 700 °C і 0,42 Омсм2 при 800 °C. Питома потужність катода SBSC становить 336,1, 387,3 і 357,4 МВт/см2 при температурі 625 °С, 650 °С і 675 °С відповідно. SBSC демонструє перспективність в якості катодного матеріалу для ПТ-ТОПЕ

Zinc cobaltite (ZnCo2O4) was successfully hybridized with conductive polyaniline (PANI) and graphitic carbon nitride (g-C3N4) as an applicable hybrid ternary composite toward supercapacitors and electrochemical glucose sensing. The electrodes were prepared in two steps, hydrothermal approach to develop ZnCo2O4/Nickel foam, followed by in situ chemical oxidative polymerization for g-C3N4/PANI over ZnCo2O4/Nickel foam. For the confirmation of synthesized materials, some of the primary characterization tools such as X-ray powder diffraction, Fourier transform infrared spectroscopy and Raman spectroscopy were used. Surface area analysis was performed by obtaining nitrogen adsorption and desorption isotherms. Considering, practical applications toward electrochemical devices, kinetics studies were carried out using the rotational disk electrodes to obtain kinetic parameters. Further, morphological images and electronic structure were obtained via field emission scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. This hybrid ternary composite electrochemical properties was analyzed using a three electrodes electrochemical cell; composites provided a synergistic effect with higher surface-active species, which exhibited a specific capacity as high as 738 F g−1 at 2 A g−1 in 6 M KOH electrolyte. For practical applications, asymmetric supercapacitors were fabricated with carbon-based electrodes, and solid-state supercapacitors were placed inside of the Swagelok cell setup for performance investigation. Supercapacitors demonstrate admirable specific capacitance of 24.8 F g−1 at 0.2 A g−1 and cycle stability with a 100% retention of specific capacitance even after 2000 cycles. Further, the asymmetric supercapacitor exhibited potential output with a power density of 375 W kg−1 and an energy density of 6.35 W h kg−1 at 0.4 A g−1. Moreover, the prepared materials were used in the application of electrochemical sensors for effective oxidation of glucose, in which kinetics were due to the diffusion-controlled electrochemical process for glucose oxidation. The ternary composite ZnCo2O4/g-C3N4/PANI-fabricated electrode delivered excellent sensor parameters with a sensitivity of 15.64 mA mM−1 cm−2 in the linear range of 0.1 mM to 3 mM with an acceptable detection limit (LOD) of 4 μM. Further, in-depth studies such as selectivity and durability were carried out to verify the effectiveness of the electrochemical glucose sensor. This work shows that the ternary composite ZnCo2O4/g-C3N4/PANI could be a potential and promising electrode material for the supercapacitor and electrochemical glucose sensing applications.

Development of an efficient, earth-abundant, inexpensive, and stable perovskite electrocatalyst to replace RuO2 catalysts for the oxygen evolution reaction (OER) is much needed for the practical application of electrochemical energy conversion devices. Herein, we report Sm0.5Sr0.5Fe0.8M0.2O3−δ (M = Co, Cu) perovskite doped with different transition metals at the B-site as a cheaper OER electrocatalyst in 1 M KOH electrolyte. Among the prepared catalysts, Sm0.5Sr0.5Fe0.8Co0.2O3−δ (SSFCoO) catalysts show improved OER activity with an on-set potential of 1.48 V vs. RHE with a lower overpotential of 316 mV at 10 mA cm−2. Furthermore, the OER performance correlated with the electronic structure of the electrocatalyst was analyzed through X-ray photoelectron spectra which revealed that the improved OER activity of the SSFCoO catalyst is due to an increased Fe4+ oxidization state. Strong Fe 3d–O 2p hybridization causes up-shifting of the O 2p valence band close to the Fermi level from 1.0 eV to 0.33 eV, significantly reducing the charge transfer energy and causing faster OH− adsorption and desorption for efficient OER activity.

A cobalt-free perovskite oxide Sm0.5Sr0.5Fe0.8Cr0.2O3-δ(SSFC) has been exploited as a novel cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The cathode model was synthesized with the addition of the chromium element in the B side of the composite metallic oxide system, which was then formed by the solid-state reaction method. The model system was further characterized in detail for getting the properties behavior. The solid-state reaction of the SSFC system was observed through thermal gravimetric analysis. Meanwhile, the structural properties were investigated by x-ray diffraction, and the weight loss was examined by the thermal gravimetric analysis as well. Furthermore, the thermal expansion coefficient was determined by the thermal-mechanical analysis, and the conductivity properties were tested by the thermal conductivity analysis. The result showed that the SSFC cathode demonstrated the crystalline structure based on the design with a perovskite phase. The oxygen content created on the model structure was obtained to be 2.98 after the calcination process. The average thermal expansion coefficient was achieved up to 5.0×10-6K-1as the heating given up to 800°С. Moreover, the conductivity value reached from 2S∙cm-1at 400°С and it increased to be a maximum of 7.5S∙cm-1at 700°С. In addition, the presence of Cr6+cation valence coordinated with the oxygen anion could lead to generating a large concentration of oxygen vacancies on the cathode surface, facilitating the transport of the O2−anion in the cathode system. Based on these results, the SSFC cathode has good properties as a composite system promising for IT-SOFCs application in the future

Two series of samarium co-doped in 10 mol% Gd doped ceria Ce0.90Gd0.1O1.95(GDC10) formulated as Ce0.9-xSmxGd0.1O2-δ(CS) and Ce0.9Gd0.1-xSmxO2-δ(GS) (x = 0.0, 0.03, 0.05 0.10) were synthesized by glycine nitrate auto combustion method. The structural effects of Sm substitution in the GDC10 solid solution have been studied by X-ray diffraction (XRD) and Raman spectroscopy techniques. An increased lattice constant (5.407 A to 5.414 A) with decreasing crystallite size (28.6 nm 22.5 nm) was observed in both the Ce substituted by Sm (CS) and Gd substituted by Sm (GS) in GDC10 crystal system. The highest oxygen vacancy concentration ( V O ⋅ ⋅ = 2.65 × 1021 cm−3) was found for 10 mol % Sm and 10 mol % Gd doped ceria (Ce0.8 Sm0.1Gd0.1O1.90) composition (CS10) evaluated by spatial correlation model from Raman spectroscopy. The microhardness of the sintered pellets was investigated by Vickers hardness measurement. The highest fracture toughness was found to be 1.85 ± 0.27 MPa m1/2 for Ce substituted by 3 mol% Sm composition (CS3) among the overall compositions. The surface morphology and elemental composition of the CS and GS compositions were analyzed by FESEM. The morphology and composition of optimized electrolyte (CS10) was further analyzed by HRTEM and XPS respectively. AC impedance spectroscopy revealed that CS10 composition has an improved ionic conductivity (σ800 = 0.147 × 10−3 S‧cm−1) with significantly reduced activation energy (0.85 eV) in the temperature range of 673–1073 K under air atmosphere. A mechanism for conductivity enhancement by oxygen vacancy for CS compositions has been proposed. The effect of Sm as a secondary co-dopant in the GDC10 electrolyte was studied in detail to establish a candidate electrolyte material for operating solid oxide fuel cells in the intermediate temperature range (673–1073 K).

Hierarchical nano-/microstructured photocatalysts have drawn attention for enhanced photocatalytic performance. Deep eutectic solvents (DESs) have been used as a green sustainable media to act as both solvent and structure-inducing agent in the synthesis of hierarchical nanomaterials. In this work, the DESs-assisted synthesis of flower-structured BiOCl/BiVO4 (BOC/BVO) with g-C3 N4 (BOC/BVO/g-CN) ternary heterojunctions was achieved by using a simple wet-chemical method, providing good acidic and alkaline oxygen evolution reaction (OER) catalysts. BOC/BVO/g-CN-15 achieved an enhanced photocatalytic activity for OER with an overpotential of 570 mV in 1 m H2 SO4 and 220 mV in 1 m KOH electrolyte at a current density of 10 mA cm-2 with excellent stability and extraordinary durability of the catalyst. The ternary heterojunctions displayed extended lifetimes for photogenerated charges and enhanced the separation efficiency of photogenerated electron-hole pairs, which is helpful to enhance the photocatalytic OER. Furthermore, the photocatalytic performance of the ternary heterojunctions in aqueous solution was demonstrated through photocatalytic dye degradation of methyl orange (MO) as a model pollutant, resulting in 95 % degradation of 20 ppm of MO in 210 min under the irradiation of a 35 W Xe arc lamp. This work not only provides new insight into the design of catalysts by using green solvents but also into the design of highly efficient metal-free OER photocatalysts for applications in acidic and alkaline media.

Nickel-doped FeS2/rGO composites were synthesized as multifunctional materials via a facile hydrothermal method. The synthesized materials were characterized with XRD, FESEM, XPS, and TEM-SAED for structural, morphological and chemical studies. To study their electrochemical properties, all the synthesized composites were subjected to cyclic voltammetry tests. The optimum composite revealed high catalytic activity with high peak current density, limiting current, and efficiency of 7.60% for DSSC, which surpassed that of a platinum-based counter electrode (6.69%). The efficiency of the DSSC was significantly supported by interfacial studies and electron lifetime studies, and it exhibited lower charge transfer resistance and higher electron lifetime, respectively. Moreover, the fabricated DSSCs with high efficiency were subjected to transient photo-response studies and showed a stable current response with multiple photo-ON and OFF cycles for a period of 600 s. To broaden the application of the synthesized material, it was used as an electrochemical sensor for the efficient sensing of hydrogen peroxide (H2O2). The sensing electrode was modified with the optimum Ni-doped FeS2/rGO composite, and voltammetric detection was carried out in the hydrogen peroxide concentration range of 4–100 μM. Thus, the synthesized material can be applied in DSSCs and as an electrochemical H2O2 sensor.

This work reports the coprecipitation synthesis and characterization of single-phase Sm3+/Sr2+/Ca2+ codoped with Gd3+ in cerium oxide formulated as Ce0.8M0.1Gd0.1O2−δ (CMGO; M = Sm3+, Sr2+, Ca2) na...

In this work we propose a study to determine the structure of Fe and Co doped TiO2 by using the Fe K-edge, Co K-edge and Ti K- edge X-ray absorption near edge spectroscopy. The detailed analysis of Fe and Co-doped TiO2 before and after Methylene blue (MB) treatment was examined under the irradiation of 35 W xenon arc lamp for 3 h. The materials treated with MB were studied by X-ray absorption spectroscopy, EPR and FT-IR which revealed that the oxidation state of Co2+ was photo-oxidized to Co3+ and Fe3+ was photo-reduced to Fe2+ or less. Thermodynamic, kinetic properties were studied at different reaction temperature and the activation energy (Ea), enthalpy (ΔH), entropy (ΔS) and free energy (ΔG) of activation were calculated for the reaction. The activation energy has been found for TiO2, Fe TiO2 and Co TiO2 as 24.771, 11.413 and 15.801 kJ mol−1 respectively. The structure, morphology and optical properties were studied by XRD, UV-diffuse reflectance spectra, FESEM, TEM and PL. Moreover, electrochemical studies were carried out to demonstrate the oxygen evolution reaction (OER) activity on TiO2, Fe TiO2 and Co TiO2 in 1 M of H2SO4 electrolyte, with a scan rate of 50 mV s−1 and the as-prepared photocatalysts could act as the promising electrode materials for water splitting.

Anion doping into the oxygen site as a new plan for tuning the physical and chemical properties of metal oxides and adjusting their catalytic behavior has been studied. Herein, we report a Cl− anion-doped CuO (Cl-CuO) preparation method using deep eutectic solvents (DESs) as a green solvent, and the Cl-CuO/g-C3N4 heterostructure was successfully prepared in various weight ratios via a simple ultrasonication and mixing method for the oxygen evolution reaction (OER) in acidic media and the photocatalytic degradation of 4-nitrophenol. Cl− was doped into the CuO crystal lattice, as revealed by the XRD and XPS studies. The as-prepared Cl-CuO/g-C3N4 (1 : 2) exhibited a low overpotential of 0.77 V on the glassy carbon electrode with a current density of 33 mA cm−2 at 2.4 V for OER in an acidic solution. Also, about 92% degradation of 20 ppm of 4-nitrophenol was achieved for Cl-CuO/g-C3N4 (1 : 2) in 100 minutes under the irradiation of a 35 W Xe arc lamp. We also evaluated the effect of thermal energy on degradation kinetics by tuning the temperature, which led us to the quantification of various thermodynamic parameters. To the best of knowledge, this is one of the new methods of green synthesis to fabricate photocatalysts for energy and environmental studies.

In this study, the crystal structure, thermal, oxygen transport, electrical conductivity and electrochemical properties of the perovskite NdBa0.5Sr0.5Co2O5+δ (NBSC55) are investigated. In the temperature range of 250 °C–350 °C, the weight loss upon heating was due to a partial loss of lattice oxygen and along with a reduction of Co4+ to Co3+. The tend of weight-loss slows down as temperature increased above 350 °C indicating a reduction of Co3+ to Co2+ during this stage. The oxygen migration is dominated by surface exchange process at high temperature range (650-800 °C); however, the bulk diffusion process prevails at low temperature range (500–600 °C). For long-term testing, the polarization resistance of NBSC55 increases gradually form 3.13 Ω cm2 for 2 h to 3.34 Ω cm2 for 96 h at 600 °C and an increasing-rate for polarization resistance is around 0.22% h−1. The power density of the single cell with NBSC55 cathode reached 341 mW cm−2 at 800 °C.

Herein, we synthesize a Cu-cuprous/cupric oxide-based family of catalysts via simple hydrothermal technique, and investigate the effect of copper oxide phases on the application of interest. These catalysts are applied towards dual application namely 4-nitrophenol (4-NP) conversion and electrochemical hydrogen evolution reaction (HER). Due to the difference in mechanism of these both applications, we pick up two best catalysts for either application. We explore these differences through intensive characterizations such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction of hydrogen (H2-TPR) analysis. XRD reveals the presence of varying copper oxide phases across all the synthesized catalysts. XPS discovers the disparities between catalysts annealed at various temperatures. Reducibility of catalysts is studied via H2-TPR since they can disclose phase conversions taking place in the material thereby directly affecting the application. Cu-Cu2O (150℃) could convert 98.6 % of 50 ppm 4-NP into 4-aminophenol (4-AP) with recycle tests up to 10 cycles yielding conversion values between 96.3–98.9% which are high enough for any catalyst to reach its maximum potential. CuO-Cu2O (300℃) exhibits best HER activity with the least onset potential of -0.28 V vs. RHE at 1 mA cm-2 possessing a maximum current density of 366 mA cm-2.

Graphene oxide-based composites have been developed as cheap and effective photocatalysts for dye degradation and water splitting applications. Herein, we report reduced graphene oxide (rGO)/Ag/Fe-doped TiO2 that has been successfully prepared using a simple process. The resulting composites were characterized by a wide range of physicochemical techniques. The photocatalytic activities of the composite materials were studied under visible light supplied by a 35 W Xe arc lamp. The rGO/Ag/Fe-doped TiO2 composite demonstrated excellent degradation of methylene blue (MB) in 150 min and 4-nitrophenol (4-NP) in 210 min under visible light irradiation, and trapping experiments were carried out to explain the mechanism of photocatalytic activity. Moreover, electrochemical studies were carried out to demonstrate the oxygen evolution reaction (OER) activity on rGO/Ag/Fe-doped TiO2 in 1 M of H2SO4 electrolyte, with a scan rate of 50 mV s−1. The reductions in overpotential are due to the d-orbital splitting in Fe-doped TiO2 and rGO as an electron collector and transporter.

The plasmonic metal-induced Bi2WO6/TiO2 ternary composite with unique electronic and structural properties was synthesized via a hydrothermal and chemical reduction route for sustainable energy and environmental remediation. The obtained Bi2WO6/TiO2-Ag (BWTA) exhibited a tremendous catalytic activity for Rhodamine B photodegradation (0.947 × 10-2 min−1) than those of sole TiO2 and Bi2WO6 specimens. The radical trapping experiment discloses that superoxide .O2− and holes (h+) are the cardinal active species in the photocatalytic system. Further, recycling experiment was conducted to elucidate the stability of the photocatalyst. BWTA2.0 was able to produce 2.1330 mA/cm2 of current density for oxygen evolution reaction and −1.5003 mA/cm2 for hydrogen evolution reaction, which is much higher than those of other specimens. Besides, electrochemical detection of dopamine (DA) was performed through cyclic voltammetry; results showed that the ternary composite had better electrocatalytic activity for DA detection owing to the synergistic effects of noble metal incorporation into the semiconductor. Also, the antibacterial potential of the specimens was explored against Escherichia coli through the well-diffusion method. In terms of experimental results, a possible mechanism of ternary composite is thoroughly elucidated. Thus, this work validates that, plasmonic induced ternary composite has a great prospect for photocatalytic, electrochemical, sensing, and antibacterial applications.

In this study, the electrochemical impedance spectroscopy (EIS) technique was used to investigate the electrochemical behavior of the interface between the Mo electrode and the Cu-In-Ga-Se electrolyte. In this electrodeposition system, the main parameters include (1) various deposition times, and (2) the effect of In 3+ concentration on the diffusion processes, electrical double layer, charge transfer resistance, and Warburg impedance. Experimental results revealed that the electrochemical kinetic behavior of CIGS thin film is strongly influenced by (1) the electrical double layer existing between the substrate, and (2) the electrolyte with different concentrations of In 3+ . With an increase in the electrodeposition time, the kinetic behavior of this electrodeposition system was gradually dominated by the diffusion process rather than charge transfer process.

Ciprofloxacin (CIP) is a fluoroquinolone family antibiotic pollutant. CIP existence in water environment has been rising very fast in day-to-day life and subsequently, it gives enormous health issues for humans because of its potent biological activity. To encounter this, current researchers are focusing on the development of highly efficient visible light semiconductor nanocomposites with potential photocatalytic activity. In the present work, we have successfully synthesized highly efficient zinc-aluminum layered double hydroxides with graphitic carbon nitride (ZALDH/CN) composites via a simple microwave irradiation method first time for the degradation of CIP under visible light. The fabricated materials are subsequently characterized by various spectroscopic techniques. UV–Vis DRS, TRFL, XRD, FT-IR, BET, FE-SEM, TEM, and XPS for optical, crystal structure, morphological, and elemental analysis. The main reactive intermediates which are formed during the photocatalytic degradation process were analyzed by LC-MS analysis. It is worth to note that, the optimized ZALDH/CN-10 composite showed the highest photo-degradation rate constant of 1.22 × 10−2 min−1 with 84.10% degradation is higher than bare CN and ZALDH photocatalysts. Based on the electron-hole pair trapping experiment results, possible CIP photo-degradation mechanism was also explained in the present study. With all results, this work demonstrates the ZALDH/CN composite materials showed a high synergistic effect with more specific surface area. Highest specific surface area leads to enhanced visible light adsorption capacity. Subsequently improved number of catalytically active sites. Furthermore, as compared with pure materials, composites of ZALDH/CN are having low electron-hole pair recombination. Consequently, the composites ZALDH/CN showed superior photocatalytic activity for antibiotic pollutant CIP degradation under visible-light illumination.

Noble metals are very well known for their surface plasmon resonance property that facilitate of better light absorption in the visible region particularly for gold and silver. Nevertheless, unlike semiconductors, noble metals are commonly considered lacking the ability to accelerate reactions by way of photogenerated electron-hole pairs due to their continuous energy band structure. Here, we report a one dimensional (1D) AgNWs combined with BiOCl/BiVO4 photocatalysts have been synthesized at room temperature. BiOCl/BiVO4 photocatalysts have been synthesized in the presence of deep eutectic solvents (DESs), also known as deep eutectic ionic liquids (DEILs).The synthesized product was characterized using various techniques. Surface morphology was analyzed using SEM and TEM, which shows a sheet like shaped structure from sol–gel method. The structural, optical properties were investigated by X-ray diffraction (XRD), UV–vis spectrophotometer, and Photoluminescence (PL) spectroscopy measurements. The BiOCl/BiVO4@AgNWs shows a better degradation of methylene blue (MB) and rhodamine B (RhB) than pure BiVO4 illuminated under a Xe arc lamp with 35 W and color temperature of 6000 K. Also, the significant enhancement of visible-light-driven photocatalytic activity should be ascribed to the formation of the BiOCl/BiVO4 heterojunction, which can result in the high separation and transfer efficiency of photogenerated charge carriers. It was verified by electrochemical impedance spectra (EIS) and linear sweep voltammetry (LSV).

SmBa 0.5 Sr 0.5 Co 2 O 5+δ (SBSC55) impregnated with nano-sized Ce 0.8 Sm 0.2 O 1.9 (SDC) powder has been investigated as a candidate cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The cathode chemical compatibility with electrolyte, thermal expansion behavior, and electrochemical performance are investigated. For compatibility, a good chemical compatibility between SBSC55 and SDC electrolyte is still kept at 1100 °C in air. For thermal dilation curve, it could be divided into two regions, one is the low temperature region (100–265 °C); the other is the high temperature region (265–850 °C). In the low temperature region (100–265 °C), a TEC value is about 17.0 × 10 −6 K −1 and an increase in slope in the higher temperatures region (265–800 °C), in which a TEC value is around 21.1 × 10 −6 K −1 . There is an inflection region ranged from 225 to 330 °C in the curve of d ( δL / L )/ dT vs. temperature. The peak inflection point located about 265 °C is associated to the initial temperature for the loss of lattice oxygen and the formation of oxygen vacancies. For electrochemical properties, the polarization resistances (R p ) significantly reduced from 4.17 Ω cm 2 of pure SBSC55 to 1.28 Ω cm 2 of 0.65 mg cm −2 of SDC-impregnated SBSC55 at 600 °C. The single cell performance of SBSC55∣SDC∣Ni-SDC loaded with 0.65 mg cm −2 SDC exhibited the optimum power density of 823 mW cm −2 at operating temperature of 800 °C. Based on above-mentioned properties, SBSC55 impregnated with an appropriate SDC is a potential cathode for IT-SOFCs.

In this article, structural properties and bonding behaviours of codoped lanthanum chromites (La0.8Ca0.2)(Cr0.9−x Co0.1Cu x )O3 (x=0.00, 0.03, and 0.12) were investigated in detail. Polycrystalline chromite samples (La0.8Ca0.2)(Cr0.9−x Co0.1Cu x )O3 (x=0.00, 0.03, and 0.12) were prepared by a standard solid-state reaction process. The synthesised samples were characterised for their structural, morphological, optical, and magnetic properties using powder XRD, SEM/EDS, UV–Vis, and VSM. XRD data showed that the samples were crystallised into a single phase with orthorhombic structure. Powder profile refinement analysis suggested the reduction in lattice parameters and cell volume with the addition of Cu. The electron density distributions and the bonding features of the prepared samples have been investigated using maximum entropy method (MEM). The mid bond electron density values revealed the enhancement of ionic nature between lanthanum and oxygen ions and a reduction in covalent nature between chromium and oxygen ions. Heterogeneous distribution of particles with different sizes was observed through SEM micrographs. EDS spectra confirms the presence of constituent elements in the prepared samples. Optical band gap values are decreasing with the addition of Cu. Antiferromagnetic ordering was observed from M–H curves obtained at room temperature. The structural and the magnetic properties are correlated.

The interfacial interactions between ionic liquids (1,3-dimethylimidazolium methyl sulfate and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate) and solid surfaces (mesoporous aluminum oxide and mica) have been studied by infrared spectroscopy at high pressures (up to 2.5 GPa). Under ambient pressure, the spectroscopic features of pure ionic liquids and mixtures of ionic liquids/solid particles (Al2O3 and mica) are similar. As the pressure is increased, the cooperative effect in the local structure of pure 1,3-dimethylimidazolium methyl sulfate becomes significantly enhanced as the imidazolium C&ndash, H absorptions of the ionic liquid are red-shifted. However, this pressure-enhanced effect is reduced by adding the solid particles (Al2O3 and mica) to 1,3-dimethylimidazolium methyl sulfate. Although high-pressure IR can detect the interactions between 1,3-dimethylimidazolium methyl sulfate and particle surfaces, the difference in the interfacial interactions in the mixtures of Al2O3 and mica is not clear. By changing the type of ionic liquid to 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, the interfacial interactions become more sensitive to the type of solid surfaces. The mica particles in the mixture perturb the local structure of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate under high pressures, forcing 1-ethyl-3-methylimidazolium trifluoromethanesulfonate to form into an isolated structure. For Al2O3, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate tends to form an associated structure under high pressures.

Herein, we synthesized a bi-function hybrid material and investigated the dynamic nature of synergy between the individual components of the hybrid and its application aspects in detail. The diverse nature of 2D-ternary hybrid could be exploited as a photocatalyst as well as an electrochemical sensor. Plate-like Bi2WO6 was hybridized with mesh-like g-C3N4 structure and subsequently rGO being loaded into it via simple hydrothermal route. Based on room temperature EPR spectra, we could interpret the inactivity of Bi2WO6 and significant activity of 2D-ternary hybrid. The hybrids were evaluated based on the photocatalytic degradation of antibiotic ciprofloxacin (CIP). Bi2WO6/g-C3N4/rGO hybrid yielded 90% degradation in 110 min while CIP photolysis only yield 4.3%. Mechanism of photocatalytic degradation was investigated via scavenger experiments which gave away the reactive radicals responsible. To investigate the effect of carrier lifetime on photocatalytic ability, time resolved fluorescence life (TRFL) experiments were performed. The relationship between reducibility and enhanced photocatalytic ability of the materials was studied via hydrogen temperature-programmed reduction (H2-TPR) measurement. Furthermore, for elaborating application of the synthesized 2D structured ternary hybrid, its electrochemical ability towards 4-nitrophenol (4-NP) sensing was also studied. An electrochemical sensitive electrode was fabricated to evaluate sensing properties towards 4-NP. To study the electrode kinetics on 4-NP solution, varying scan rate was used via the cyclic voltammetry (CV) analysis. The fabricated BCN-200/rGO electrode delivered promising sensing properties with excellent sensitivity of 12.86 μA.μM−1.cm−2 in range of 0.2–100 μM. Hence, the synthesized 2D-ternary hybrid possesses great potential applications in the field of photocatalysis as well as electrochemical sensor.

Metal-organic frameworks (MOFs) are evolving as emerging materials for application in supercapacitors on account of their inherent porous characteristics, which can be suitably controlled with molecular engineering. This allows suitable attributes to MOFs such as multiple dimensionalities, high surface area and additional aspect ratio compared to traditional materials. Secondary building units (SBUs) are the milestones that allow immense structural diversity, thermodynamic stability, and mechanical/architectural stability to demonstrate materials on-demand with predetermined topologies in the synthesis of MOFs through stronger bonding between the constituent metals and organic linkers. Despite these advancements, the usage of pristine MOFs is lagging in the area of supercapacitor, majorly due to their insulating nature. As smart avenues, hybridization of MOFs or using MOFs as templates for deriving metal oxide, carbon or hydroxides etc., are being proved as hugely successful. This review is directed towards the utilization of MOFs, specifically three-dimensional MOFs as a platform for utilization in supercapacitor. Extensive discussion is developed on divergent methods related to the synthesis of MOFs, their performance in supercapacitor application and various strategies adopted to enhance their functionality. Finally, the future prospective and possible research proceedings in this field are described briefly.

Fabrication of an efficient, stable, and versatile photocatalysts for the energy and environment remediation applications is an urgent task for the current researchers. In this work, we have successfully synthesized a versatile hybrid photocatalysts, i.e.; CdMoO4/g-C3N4 (CMO/CN) by a facile and simple one-pot in-situ hydrothermal method. Here CdMoO4 (CMO) microspheres were deposited on the g-C3N4 (CN) sheets. Fabricated CN, CMO, and CMO/CN composite photocatalysts were analyzed with various characterization techniques like UV–visible diffuse reflectance spectra (UV–Vis DRS), photoluminescence spectroscopy (PL), time-resolved fluorescence lifetime (TRFL), electrochemical impedance spectroscopy (EIS), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy–energy-dispersive X-ray analysis (SEM-EDX), transmission electron microscope (TEM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET). The results reveal that the formation of a strong heterojunction between two semiconductors leads to the formation of active photocatalyst. Furthermore, as-synthesized materials were tested for the photoelectrocatalytic (PEC) oxygen evolution reactions (OERs) in acidic medium, and photocatalytic (PC) degradation of methylene blue (MB) under light irradiation. Among all tested samples, CMO/CN-10 has shown the highest current density 52.74 mA cm−2 at 1.95 V with lowest over potential of 0.70 mV on glassy carbon electrode for OER in acidic medium under the light irradiation. The PC degradation rate constant of CMO/CN-10 composite in MB solution is k = 2.0 × 10−2 min−1, whereas for the pure CMO and CN degradation rate constant is k = 5.7 × 10−3 min−1 and k = 1.2 × 10−2 min−1, respectively. This enhancement in PEC and PC properties is due to the fast migration of photo-induced electrons in the case of CMO/CN-10 nanocomposite. Trapping experiment results reveal the major reactive species for PC degradation of MB is •OH (hydroxyl radicals) and h+ (holes), respectively, and suitable PC reaction mechanism also proposed for CMO/CN-10 composites. Based on the above remarkable results, it would be a potential nanocomposite for the PEC oxygen evolution and PC degradation of MB under light illumination.

The development of perovskite-based materials with a narrow bandgap for oxygen evolution reactions (OER) and wastewater treatment have much attention in recent years. Herein, a narrow bandgap of Ca-doped BiFeO3 (BCFO) is synthesized by a simple auto combustion method. To create oxygen vacancies by doping Ca2+ the place of Bi3+, the amount of Fe3+ valence state is changed as well. 0.15% of Ca doped BiFeO3 (BCFO-15) indicate a high content of Fe4+ state with a conduction band and valence band located at 0.615 V and 2.46 V vs. NHE, respectively. The electrochemical OER of BCFO-15 observed a lower onset potential of 2.13 V vs. RHE, in acidic with a current density of 25.64 mA cm−2. In alkaline electrolyte, onset potential was observed at 2.10 V vs. RHE, with a current density of 65.87 mA cm−2. Furthermore, the photocatalytic performance of the perovskites in aqueous solution was demonstrated through photocatalytic reduction of Cr(VI) as a model pollutant, resulting in an 89.92% reduction of 50 ppm of Cr(VI) in 210 min under the irradiation of a 35 W Xe arc lamp. These findings suggest that simple divalent doping of Ca into pure BiFeO3 results in excellent photocatalytic and electrocatalytic perovskites.

The purpose of this project is investigate the oxidation reaction of 2,3,6-Trimethylphenol (TMP) green chemistry process design for magnetic nano-catalysts by microwave-induced combustion process. Design chemical syntheses to prevent waste, in order to reduce the raw materials cost, to improve the performance for 2,4,6-Trimethylbenzoquinone(TMBQ) production, and by the way to solve the environmental pollution problem from the scraps. The whole project will be completed that, Preparation of magnetic Cu–Zn ferrite nano-catalysts (Cu1-XZnXFe2O4) by microwave-induced combustion process, the characterized of catalysts and micro-structure was carried out. The kinetics and mechanism of two phase medium are also studied in Cu–Zn ferrite/TiO2 magnetic nano-catalysts.

The doped lanthanum chromite (La 0.8 Ca 0.2 )(Cr 0.9− x Co 0.1 Mn x )O 3 ( x =0.03, 0.06, 0.09 and 0.12) were synthesized by solid state reaction technique. The samples have been characterized by X-ray diffraction for structural and charge density analysis. XRD data show that the grown samples are orthorhombic in structure with single phase. The spatial charge density distribution in the unit cell for the synthesized samples has been studied using maximum entropy method. Further, the samples were analyzed by UV–visible spectrometry for optical properties and scanning electron microscopy for surface morphology. From the optical data, it was found that the direct band gap of the samples range from 2.27 to 2.46 eV. The samples were also investigated by vibrating sample magnetometry for magnetic properties. From VSM data, it is inferred that all the samples in this series are found to be predominantly antiferromagnetic in nature. Since the doped lanthanum chromites have good mechanical properties and electrical conductivity at high temperature, these materials are used in solid oxide fuel cells (SOFC).

The effects of Sr doping on the Ba-site of SmBaCo2O5+δ in term of structure characteristics, thermal expansion coefficients (TECs), electrical properties and electrochemical performance have been investigated as cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The TECs of SBSC-based cathodes are calculated from 19.8 − 20.5 × 10−6 K−1 in the temperature range of 100–800 °C, and the TEC values decrease with increasing Sr content. The oxygen content and the average oxidation state of cobalt increase with increasing Sr content determined by the X-ray photoelectron spectroscopy (XPS) and Thermogravimetry analysis (TGA) results. At a given temperature, the electrical conductivity values are in the order as follows: SBSC55 > SBSC73 > SBSC91. This behavior might be due to the increase in electronic hole. The electrical conductivities of SBSC55 at 600 °C are distributed in the range of 660 S/cm of p(O2) = 0.01 atm to 1168 S/cm of p(O2) = 0.21 atm, indicating that the cathode can endure reducing atmosphere. SBSC55 with high electrical conductivity in p(O2) = 0.01 atm is ascribed to SBSC55 with stable double-perovskite structure at such low oxygen partial pressure. The SBSC55 cathode showed the highest power density of 304 mW/cm2 at operating temperature of 700 °C. Based on the electrochemical properties, SBSC55 is a potential cathode for IT-SOFCs.

Transition metal-doped lanthanum chromites (La0.8Ca0.2)(Cr0.9−x Co0.1Fe x )O3 (x = 0.03, 0.06, 0.09, 0.12) have been synthesized by solid state reaction method. The synthesized samples were characterized for their structural properties using powder x-ray diffraction analysis, which shows that the grown samples are orthorhombic in structure with single phase. The nature of bonding and the charge distribution of the grown samples have been analyzed by maximum entropy method. Further, the samples were characterized for their optical and magnetic properties using ultraviolet–visible spectra and vibrating sample magnetometry. The microstructural studies were carried by scanning electron microscopy/electron dispersive x-ray spectroscopy techniques. From the optical absorption spectra, it was found that the energy band gap of the samples ranges from 2.135 eV to 2.405 eV. From vibrating sample magnetometer measurements, ferromagnetic like behaviour with large coercive field was observed for Fe doping concentration of x = 0.12. Since the doped lanthanum chromites have good mechanical properties and electrical conductivity at high temperature, these materials are used in solid oxide fuel cells.

The purpose of the research was to determine the photocatalytic degradation efficiency of acid orange 7 (AO7) using 2 mol% Fe-doped TiO2 as photocatalysts under UV irradiation. Fe-doped TiO2 powder synthesized by solid-reaction technique reveals the average particle size of 0.91 μm, BET surface area of 11.6 m2/g, a wide pore-size distribution with the average pore diameter of 3.2 nm and pore volume of 0.035 cm3/g. Within the experiment, AO7 was prepared as a synthetic textile wastewater at the initial concentration of 34 mg/L along with using various doses of Fe-doped TiO2 photocatalysts. The results indicated that Fe-doped TiO2 with dose of 0.100 g in 100 mL of AO7 reached the highest removal efficiency about 88.7%.

Heterostructured nanomaterials can paid more significant attention in environmental safety for the detection and degradation/removal of hazardous toxic chemicals over a decay. Here, we report the preparation of hierarchically nanostructured shuriken like bismuth vanadate (BiVO4) as a bifunctional catalyst for photocatalytic degradation and electrochemical detection of highly toxic hexavalent chromium (Cr(VI)) using the green deep eutectic solvent reline, which allows morphology control in one of the less energy-intensive routes. The SEM results showed a good dispersion of BiVO4 catalyst and the HR-TEM revealed an average particle size of ca. 5–10 nm. As a result, the BiVO4 exhibited good photocatalytic activity under UV-light about 95% reduction of Cr(VI) to Cr(III) was observed in 160 min. The recyclability of BiVO4 catalyst exhibited an appreciable reusability and stability of the catalyst towards the photocatalytic reduction of Cr(VI). Also, the BiVO4-modified screen printed carbon electrode (BiVO4/SPCE) displayed an excellent electrochemical performance towards the electrochemical detection of Cr(VI). Besides, the BiVO4/SPCE demonstrated tremendous electrocatalytic activity, lower linear range (0.01–264.5 μM), detection limit (0.0035 μM) and good storage stability towards the detection of Cr(VI). Importantly, the BiVO4 modified electrode was also found to be a good recovery in water samples for practical applications.

The microstructure, lattice parameters, and electrical conductivity mechanisms for Fe doping on B-site of (La0.8Ca0.2)(Cr0.9Co0.1)O3−δ were systematically investigated. The oxygen nonstoichiometry was measured by means of thermogravimetry as a function of oxygen partial pressure. In this study, the concept of defect chemistry is used to explain the relationship between the concentration of electron hole with the electrical conductivity. Based on the result of electrical conductivity in air, it is concluded that the concentration of electron hole at high oxygen activity is larger than that at low oxygen activity. This is due to the fact that (La0.8Ca0.2)CrO3−δ-based ceramics are p-type conductors, the electrical conductivity is dominated by the concentration of hole. At higher Fe-doping level, the compensation mechanism at high oxygen activity is significantly dominated by the formation of oxygen vacancy, that is, ionic compensation. The compensation mechanism at low oxygen activity is significantly dominated by the formation of the formation of Cr4+, that is, electrical compensation at lower Fe-doping level. Based on oxygen nonstoichiometry data, it is found that with increasing Fe-doping amount on B-site of (La0.8Ca0.2)(Cr0.9Co0.1)O3−δ specimens, the initial weight-stable temperature shifted to lower temperature which might be highly related with the change in compensation mechanism at the temperature.

The chemical stability of potassium substituted for A-site of SrCe 0.95 Y 0.05 O 3 specimens was examined under CO 2 atmosphere treated at 600 °C and further analyzed by X-ray diffractometer to see their CO 2 -resisted capabilities. According to thermodynamic data, the Gibbs free energy of CeO 2 was lower than that of SrCO 3 at the temperature of 600 °C. Thus the formation of CeO 2 might be faster than that of SrCO 3 in SrCeO 3− based materials under CO 2 atmosphere. Unfortunately, the chemical stability of SrCe 0.95 Y 0.05 O 3 materials in CO 2 atmosphere was reduced with increasing potassium-substituted amount. The microstructures of Sr 1− x K x Ce 0.95 Y 0.05 O 3 sintered specimens were identified using field emission scanning electron microscope. The conductivity in moisture H 2 atmosphere (RH 30%) was increased with increasing potassium-substituted concentration. The conductivity reached a maximum of 0.0081 Scm -1 at 900 °C for Sr 0.95 K 0.05 Ce 0.95 Y 0.05 O 3 sintered specimens in moisture H 2 atmosphere (RH 30%). Potassium substituted for A-site of SrCe 0.95 Y 0.05 O 3 could improve the conductivity but not CO 2 -resisted capability.

The microstructure, lattice parameters, morphology, mechanical properties, and conductivity of BaCe0.9M0.1O2.95 (M=Gd, Nd, Sm, Y) were systematically investigated under different atmospheres (in air and in wet 5%H2–95%Ar). The XRD results indicated that all of the specimens sintered in air have orthorhombic symmetry, whereas BaCeO3 and BaCe0.9Gd0.1O2.95 decomposed into CeO2 and BaCO3 in their specimens. Secondary CeO2 and BaCO3 might adversely affect the conductivity of BaCeO3-based specimens. The maximum conductivity (σtotal,800 °c=6.46×10−3 S/cm) and minimum activation energy (Ea=52.3 kJ/mol) measured in air were observed for BaCe0.9Y0.1O2.95 among the BaCeO3-based specimens, Whereas in wet 5%H2–95%Ar, the maximum conductivity (σtotal,800 °c=9.20×10−3 S/cm) and minimum activation energy (Ea=55.6 kJ/mol) were measured. The difference in conductivity between the air and wet reducing atmosphere can be explained by the chemical stability. The mechanical properties of BaCe0.9M0.1O2.95 significantly depended on the doping element with the rare-earth oxide dopants affecting the structure stability, grain size, conductivity, thermal expansion, and the mechanical properties. Based on a comprehensive evaluation, BaCe0.9Y0.1O2.95 revealed good chemical stability and high conductivity and thus it is a promising candidate for a proton-conducing electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs).

In the first part of this study, the characteristics of a La0.5Sr0.5CoO3−δ cathode are described, including its chemical bulk diffusion coefficient (Dchem), and electrical conductivity relaxation experiments are performed to obtain experimental Dchem measurements of this cathode. The second part of this study describes two methods to improve the single-cell performance of solid oxide fuel cells. One method uses a composite cathode, i.e., a mix of 30 wt% electrolyte and 70 wt% cathode; the other method uses an electrolyte-infiltrated cathode, i.e., an active ionic-conductive electrolyte with nano-sized particles is deposited onto a porous cathode surface using the infiltration method. In this work, 0.2M Ce0.8Sm0.2O1.9 (SDC)-infiltrated La0.5Sr0.5CoO3−δ exhibits a maximum peak power density of 1221 mW/cm2 at an operating temperature of 700°C with a thick-film SDC electrolyte (30 μm), a NiO + SDC anode (1 mm) and a La0.5Sr0.5CoO3−δ cathode (10 μm). The enhancement in electrochemical performances using the electrolyte-infiltrated cathode is attributed to the creation of electrolyte/cathode phase boundaries, which considerably increases the number of electrochemical sites available for the oxygen reduction reaction.

A Fe–Cr alloy, used for metallic interconnects, was coated with a protective layer of lanthanum strontium manganite (LSMO) using the aerosol deposition method (AD). The effects of the LSMO protective layer, which was coated on the Fe–Cr interconnects using AD, on the area specific resistance (ASR) during high temperature oxidation and the Cr evaporation behaviors were systematically investigated in this paper. The microstructures, morphologies, and compositions of the oxidized scales that appeared on the LSMO-coated Fe–Cr alloy after annealing at 800 °C for 750 h in air were examined using SEM equipped with EDS. The EPMA mapping of the LSMO-coated Fe–Cr interconnects undergoing long term, high-temperature oxidation was used to explain the formation layers of the oxidized scale, which consists of (Mn,Cr) 3 O 4 and Cr 2 O 3 layers. Moreover, the experimental results revealed that the AD process is a potential method for preparing denser protective layers with highly desirable electrical properties for metallic interconnects.

In this study, ZnO films, prepared by Chemical Bath Deposition (CBD), are applied as the conductive layers for thin film solar cells. Zinc acetate is used as a source of zinc, and different proportions of ammonia solution are added and well mixed. The growth of zinc oxide films in reaction solutions is taken place at 80°C and then heated to 500°C for one hour. In this study, the different ammonia concentrations and deposition times is controlled. The thin film structure is Hexagonal structure, which is determined by X-ray diffraction spectrometer (XRD) analysis. Scanning electron microscopy (SEM) is used as the observation of surface morphology, the bottom of the film is the interface where the heterogeneous nucleation happens. With the increase of deposition time, there were a few attached zinc oxide particles, which is formed by homogeneous nucleation. According to UV / visible light (UV / Vis) absorption spectrometer transmittance measurements and the relationship between/among the incident wavelength, it can be converted to the energy gaps (Eg), which are about 3.0 to 3.2eV, by using fluorescence spectroscopy analysis. The emission of zinc oxide films has two wavelengths which are located on 510nm and 570nm. According to Based on the all analytic results, the ammonia concentration at 0.05M, and the deposition time is 120 minutes, would obtain the conditions of ZnO films which is more suitable for applications of conductive layer material in thin film solar cell.

We successfully prepared the TiO 2 @Mn-Zn ferrite composite powder for magnetic photocatalyst. The core Mn-Zn ferrite powder was synthesized by using steel pickling liquor and used alkaline batteries as the starting materials. The shell TiO 2 nanocrystal was prepared by sol–gel hydrolysis precipitation of titanium isopropoxide (Ti(OC 3 H 7 ) 4 ) on the Mn-Zn ferrite powder. The thickness of the titania shell was found to be approximately 2 nm. The core of Mn-Zn ferrite is of spherical or elliptical shape and the particle size of the core is in the range of 20–40 nm. The magnetic Mn-Zn ferrite nanopowder is uniformly encapsulated in a titania layer forming the core–shell structure of TiO 2 @Mn-Zn ferrite powder. The magnetic photocatalyst can be successfully used to treat dye waste waters.

This work divided into two parts. The first part reports the characteristics of a La 0.8 Ca 0.2 CoO 3− δ (LCCO) cathode including its chemical bulk diffusion coefficient ( D chem ) and chemical surface exchange coefficient ( k chem ) measured by an electrical conductivity relaxation (ECR) technique. The second part reports two methods to improve the performance of solid oxide fuel cells (SOFCs). One is the use of composite cathode, i.e., mixture of 30 wt% electrolyte and 70 wt% cathode. The other is the use of electrolyte-infiltrated cathode, i.e., the active ionic-conductive electrolyte with nanosize was infiltrated onto a porous cathode surface. In this work, the 0.2 M Ce 0.8 Sm 0.2 O 1.9 (SDC)-infiltrated La 0.8 Ca 0.2 CoO 3− δ (LCCO) reveals the maximum peak power density of 305 mW cm −2 at operating temperature of 800 °C with a thin film SDC electrolyte (30 μm), a Ni+SDC anode (1 mm) and a SDC-infiltrated LCCO cathode (20 μm). The enhancement in electrochemical performances by using the electrolyte-infiltrated cathode is ascribed to the creation of electrolyte/cathode phase boundaries, which considerably increase the electrochemical sites for oxygen reduction reaction. Therefore, the infiltrated method is a potential way to improve the performance of SOFCs.

This study investigates the microstructure and electrochemical properties of Sm 0.5 Sr 0.5 Co 0.8 Cu 0.2 O 3− δ (SSC-Cu) cathode infiltrated with Ce 0.8 Sm 0.2 O 1.9 (SDC). The newly formed nanosized electrolyte material on the cathode surface, leading the increase in electrochemical performances is mainly attributed to the creation of electrolyte/cathode phase boundaries, which considerably increases the electrochemical sites for oxygen reduction reaction. Based on the experiment results, the 0.4 M SDC infiltration reveals the lowest cathode polarization resistance ( R P ), the cathode polarization resistances ( R p ) are 0.117, 0.033, and 0.011 Ω cm 2 at 650, 750, and 850 °C, and the highest peak power density, are 439, 659, and 532 mW cm −2 at 600, 700, and 800 °C, respectively. The cathode performance in SOFCs can be significantly improved by infiltrating nanoparticles of SDC into an SSC-Cu porous backbone. This study reveals that the infiltration approach may apply in SOFCs to improve their electrochemical properties.

Currently, Taiwan's major source of gravel for construction purposes is its river systems; however, over exploitation could potentially deplete this source. To address this problem and reduce dependence on natural aggregate exploitation, this article investigates artificial lightweight aggregates (ALWAs) synthesized from industrial waste such as sewage sludge and sewage-sludge-derived ash. The ALWAs were synthesized from the sewage sludge and ash using Na2CO3. The sodium carbonate helps produce the required viscous glassy phase (needed for ALWA sintering) at a lower co-melting temperature than would otherwise be possible. Water absorption, apparent porosity, bulk density and compressive strength of the ALWAs were tested to assess resource-recycling feasibility. The required dosages of Na2CO3 were 16 and 22 wt % for conditioned sludge and ash, respectively. The dosed sludge sample required preheating at 400°C for 0.5 h, followed by sintering at 900°C for 5 min. The ash sample required sintering only at 900°C for 15 min. The sludge-derived ALWAs gave the following percentages 2.84%, 3.31%, 1.20 g/cm3, and 13.0 MPa for water absorption, apparent porosity, bulk density, and compressive strength, respectively. The corresponding values for ash-derived ALWAs were: 4.85%, 6.55%, 1.41 g/cm3, and 87.3 MPa, respectively. The characteristics of ALWAs derived in this study were then compared to those of commercially available lightweight aggregates—Lytag and Arlita F7. The characteristics mentioned above of the former were superior than those of the latter except that the value ofdensity was an interval value between Lytag and Arlita. © 2012 American Institute of Chemical Engineers Environ Prog, 32: 740–748, 2013

Modified perovskite ceramics (La 0.9 Ca 0.1 )(Co 1− x Ni x )O 3− δ ( x = 0–0.3) cathodes for solid oxide fuel cells (SOFCs) were synthesized by solid state reaction. The lattice parameters, electrical conductivity, activation energy, and microstructures of these specimens were investigated systematically in this study. The results exhibited that all specimens are rhombohedron structures and their tolerance factors were greater than 0.97, indicating that the perovskite was not distorted by Ni 2+ cation substitution for the B site of (La 0.9 Ca 0.1 )CoO 3− δ . The microstructures of the (La 0.9 Ca 0.1 )(Co 1− x Ni x )O 3− δ specimens showed good densification, and were well-sintered, with few pores. The electrical conductivity behavior conformed to the nature of a semiconductor, for all specimens. As x = 0.1, the electrical conductivity reached the maximum value of 750.3 S/cm at 800 °C, and the activation energy calculated from the Arrhenius plot of the electrical conductivity versus the reciprocal of temperature is 7.1 kJ/mol. The novelty of this study is its introduction of the concept of defect chemistry to explain the relationship between compensation mechanisms and electrical conductivity. The information gleaned regarding charge compensation mechanisms and defect formation may be valuable for a better understanding of the cathode of (La 0.9 Ca 0.1 )(Co 1− x Ni x )O 3− δ ceramics used for SOFCs. Moreover, the information about oxygen content versus temperature is useful for expressing the relationship between electrical conductivity and composition. Therefore, we also used thermogravimetric analysis combined with the room-temperature oxygen content which was determined by iodometric titration to investigate the oxygen content from room temperature to high temperature, in air. Based on the experimental results, the (La 0.9 Ca 0.1 )(Co 0.9 Ni 0.1 )O 3− δ specimen shows high electrical conductivity. Consequently, it is identified as a promising candidate for cathode SOFC applications.

This study investigates Sm 0.5 Sr 0.5 CoO 3− δ (SSC)–Ce 0.8 Sm 0.2 O 1.9 (SDC) composite cathodes with a gradual change in composition from electrolyte to the cathode in an attempt to discover a potential approach applicable to solid oxide fuel cells (SOFCs). The gradual change in composition from electrolyte to cathode shows the decline in charge transfer resistance ( R 2 ) and gas phase diffusion resistance ( R 3 ). Because the value of R 3 is always larger than R 2 and R 3 significantly dominates the total cathode polarization resistance ( R P ) at temperatures within the range of 750–850 °C, i.e., in this temperature range, the rate-determining step is dominated by the diffusion or dissociative adsorption of oxygen. The functionally gradient cathode with a graded interface between cathode and electrolyte reveals both a higher exchange current density ( i 0 ) and a lower activation energy for oxygen reduction reaction (ORR), which suggests that the ORR kinetics can be improved by using the configuration of a functionally gradient cathode.