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Investigating the properties of composite oxide for intermediate temperature solid oxide fuel cells (IT-SOFCs) has been done as a new cathode material. Using a solid-state reaction method, the metallic oxide material has been employed to create the composite model system. During the sintering process, a model system of Sm0.5Sr0.35Ba0.15FeO3-δ (SSBF15) was constructed. Thermal gravimetric analysis (TG) was played to utilize the oxygen content and weight loss of the model. In the meantime, the structure of the composite was characterized using X-ray diffraction (XRD), and the conductivity properties were tested by thermal conductivity. The structural design was made possible by the findings, which revealed that the composite model structure exhibited the crystalline structure with perovskite phase. Weight losses during the construction of the structure were reflected in the decomposition and evaporation of the composite's constituent parts. After the calcination process up to 950 °C, the model system's formation oxygen content was obtained of 2.94 in 800 °C. The electrical conductivity maximum obtained in 12.2 S·cm-1 at 430 °C. At low temperatures, the conductive behavior was affected by the metallic element, while at higher temperatures, it was influenced by the ionic structure. As a result, mixed ionic and electric conductors (MIEC) were extensively utilized in the process of generating the conductive properties. The SSBF15 composite has a good chance of being used as an alternative cathode material with a perovskite single phase for future IT-SOFCs applications based on the structure and conductivity results. Additional testing and observation are required to determine the resistance's value when incorporated into the electrolyte and its heat expansion properties, Як новий катодний матеріал було проведено дослідження властивостей композитного оксиду для твердооксидних паливних елементів проміжної температури (ТПЕПТ). Використовуючи метод твердотільної реакції, матеріал оксиду металу був використаний для створення композитної модельної системи. У процесі спікання було побудовано модельну систему Sm0.5Sr0.35Ba0.15FeO3-δ (SSBF15). Проведено термогравіметричний аналіз (ТГА) для використання вмісту кисню та втрати ваги моделі. Тим часом, структура композиту була охарактеризована за допомогою рентгенівської дифракції (РД), а властивості провідності були перевірені за допомогою теплопровідності. Структурний дизайн став можливим завдяки рішенням, які показали, що складова модельна структура має кристалічну структуру із фазою перовскіту. Втрати ваги при зведенні конструкції відбилися на розкладанні та випаровуванні складових частин композиту. Після процесу прожарювання до 950 °С вміст пластового кисню у модельній системі було отримано 2,94 при 800 °С. Максимум електропровідності отримано при 12,2 С см-1 при 430 °С. За низьких температур на провідну поведінку впливав металевий елемент, а при вищих температурах на нього впливала іонна структура. В результаті змішані іонні та електричні провідники (ЗІЕП) широко використовувалися в процесі створення властивостей, що проводять. Композит SSBF15 має хороші шанси на використання як альтернативний катодний матеріал з однофазним перовскітом для майбутніх застосувань ТПЕПТ на основі результатів дослідження структури та провідності. Додаткові випробування та спостереження необхідні для визначення значення опору при включенні в електроліт і його властивостей теплового розширення

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.

Deep eutectic solvents (DES) consisting of EG-(ChCl: C

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.

The immense need to build highly efficient catalysts has always been at the forefront of environmental remediation research. Herein, we have synthesized dual-phase copper oxide containing Cu2O and CuO originating from the same reaction using hexamethyltetramine (HMT). Simultaneously, we coupled it with g-C3N4 (g-CN), constructing a triple synergetic heterojunction, which is reported significantly less often in the literature. Hydrothermal reactions led to the formation of various catalysts, namely, Ag-Cu2O-CuO-gCN (ACCG), Ag-CuO-gCN (ACG), Ag-Cu2O-CuO (ACC) and Ag-CuO (AC), which were thoroughly characterized via XRD and FESEM to gain structural, crystallographic and morphological insights. We clearly observed the pure phase formation of the catalysts and the development of sheet-like CuO and truncated octahedrons of Cu2O fused together within the g-CN framework. Also, XPS studies revealed the presence of copper in two different oxidation states, namely, Cu2+ and Cu+. BET analysis was performed to analyze the surface area and pore volume of the catalysts, which play very significant roles in catalytic reduction. The catalytic efficiencies of the catalysts were evaluated via the reduction of 100 ppm 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) without using any light irradiation. The most efficient catalyst was ACCG, revealing the reduction of 4-NP in 4 minutes. Both Cu2O and g-CN played significant roles in reduction, following zero-order kinetics, unlike that which is often reported in the literature. We also evaluated the catalytic reduction with different concentrations of 4-NP and tuning the catalyst amount as well. A mechanism was postulated based on the XRD results of the post-catalytic reduction catalyst. The ACCG catalyst was also successfully tested as an effective dopamine sensor. The GC/ACCG electrode exhibited oxidation peak current density of 0.28 mA cm−2, which was much higher than those of the other catalysts. This unique combination of pure phase materials to form a composite as an effective catalyst as well as a sensor is an exclusive effort towards environmental remediation.

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.

An efficient Bi2WO6 catalyst with Co2+ substitution was synthesized via a facile hydrothermal route, and the materials were characterized by P-XRD, FT-IR, FE-SEM, XPS, DRS, BET and PL techniques. The obtained Co2+ substituted Bi2WO6 materials displayed high photocatalytic activity for organic dye degradation; 97.5% of the dye was photodegraded by 5 mol% of Co2+ substituted Bi2WO6 within 240 min induced by the visible light, which was remarkably better than the degradation of the bare and Co2+ substituted Bi2WO6 (1, 3, 7 and 9% Co2+ concentration). Based on the structural, optical and elemental characterization, it was determined that the substitution of the Co2+ ions in the Bi2WO6 lattice to replace the W6+ ion sites occurred without substantial changes in the crystal structure. The substituent Co2+ played a strategic role, which narrowed the band gap, leading to an enlargement in visible light absorption ability and suppressing the recombination of photogenerated electron–hole pairs credited to the Co2+ inner energy state. Additionally, the photocatalytic mechanism was elucidated by performing the radical trapping experiments, which disclosed that holes (h+) were the main species responsible for the RhB degradation. In addition, the stability of the catalysts was tested by performing recycling experiments. After the four repeating cycles, the degradation efficiency was not dramatically reduced. The results of this study disclosed that Co2+ substitution of W6+ may offer an alternative approach to enhance the Bi2WO6 photocatalytic activity.

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

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.

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.

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.

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.

Ag nanoparticles with different weight percentage loaded on Ni-Cu-Zn ferrite@SiO 2 @TiO 2 composite were successfully prepared via sol-gel method. The effect of deposited amount of Ag nanoparticles on structural, magnetic and photocatalytic properties of the composite was investigated. XPS characterization confirmed that Ag nanoparticles deposited on the surface of Ni-Cu-Zn ferrite@SiO 2 @TiO 2 composite. Particle size and shape of magnetic recyclable photocatalysts were observed using TEM, showing a core-shell structure with an average particle size of 20 nm of Ag. Based on room temperature magnetic hysteresis curves, as 0.4 wt% Ag immobilized on Ni-Cu-Zn ferrite@SiO 2 @TiO 2 composite revealed the maximum saturation magnetization of 39.9 emu/g. Photocatalytic degradation of Ni-Cu-Zn ferrite@SiO 2 @TiO 2 @Ag was carried out in methylene blue (MB) solutions illuminated under a 35-W Xe arc lamp and color temperature of 6000 K. The results revealed that 83.9% of MB was photodegraded for 0.4 wt% of Ag-loaded Ni-Cu-Zn ferrite@SiO 2 @TiO 2 . Moreover, it can be easily separated and recycled without significant loss of photocatalytic activity after being used five times. Compared to the conventional photocatalysts, the magnetic core–shell photocatalyst is suitable for large scale applications in industrial wastewater system.

Oxygen transportation properties of SmBa0.5Sr0.5Co2O5+δ (SBSC55) layered perovskite has been investigated as a potential cathode for intermediate-temperature solid oxide fuel cells (IT-SOFCs). This research includes the following items: (1) structural characteristics, thermogravimetric behavior, oxygen permeation, chemical bulk diffusion coefficient (Dchem), and (2) the electrochemical performance of long-term testing carried out to evaluate its electrochemical stability. The Dchem values for SBSC55 cathode are 2.6 × 10−6, 9.1 × 10−6 and 1.8 × 10−5 cm2 s−1 at 500 °C, 600 °C, and 700 °C, respectively. The oxygen permeation flux for SBSC55 membrane with 1.0 mm thickness increased from 0.143 mL min−1 cm−2 at 500 °C to 0.406 mL min−1 cm−2 at 800 °C under synthetic air at a flow rate of 50 mL min−1, helium at a rate of 25 mL min−1. The activation energies of oxygen permeation for the high temperature region (700–800 °C) and low temperature region (500–650 °C) are 23.67 and 6.96 kJ mol−1, respectively. It suggested that oxygen diffusion for high temperature range is surface exchange process, low temperature range is bulk diffusion process. The long-term test of cathodic polarization resistance for SBSC55∣SDC∣SSBSC55 half-cell at 600 °C during 96 h has been carried out with an increase rate of 0.30% h−1. Based on the impedance spectra with various oxygen partial pressure results, the rate-limiting process of ORR is determined that the oxygen ion transfer from triple-phase boundary (TPB) and/or two-phase boundary (2PB) sites of cathode is major with the minority of charger transfer reaction.

In this study, the double perovskite LaBa0.5Sr0.5Co2O5+δ (LBSC55) is investigated as a potential cathode for solid oxide fuel cells (SOFCs). In the curve of the first derivative δL vs. temperature, there is an inflection region ranging from 230 to 330 °C. The peak inflection point located about 260 °C is associated with the initial temperature for the loss of lattice oxygen and the formation of oxygen vacancies. The concentration of Co4+ ions in LBSC55 decreased significantly above 260 °C due to the loss of lattice oxygen (Co4+ → Co3+) and creation of at the same time. The electrical conductivity exhibited a metallic behavior with values that gradually decreased from 232 S cm−1 at 400 °C to 178 S cm−1 at 800 °C. The chemical bulk diffusion coefficient (Dchem) values of LBSC55 are 1.49 × 10−4, 2.75 × 10−4 and 5.37 × 10−4 cm2 s−1 at 700 °C, 750 °C and 800 °C, respectively. The oxygen permeation flux for LBSC55 membrane with 1.0 mm thickness increased from 0.210 mL min−1 cm−2 at 500 °C to 0.302 mL min−1 cm−2 at 800 °C under synthetic air at a flow rate of 50 mL min−1, with helium at a rate of 25 mL min−1. The activation energies of oxygen permeation for the high temperature region (750–800 °C) and low temperature region (500–700 °C) are 10.60 and 2.75 kJ mol−1, respectively. This suggested that the surface exchange process is dominant above 750 °C and at low temperature ranges the bulk diffusion process is dominant for oxygen ion diffusion. The main process of the oxygen reduction reaction is dominated by oxygen ion transfer from TPB and/or 2PB sites of the cathode to electrolyte in the temperature range of 600–800 °C. Based on the chemical bulk diffusion coefficient, oxygen permeation and electrochemical properties, LBSC55 is a potential cathode for solid oxide fuel cells (SOFCs).