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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.

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

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

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.

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.

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.

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.

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.

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.

The aim of the work is to study the effects of oxygen vacancy and surface hydroxyl group density on the photocatalytic activity of Fe3+-doped TiO2, and to investigate how the titanium dioxide doped with different levels of the Fe3+ influenced their physical and chemical characterizations. The photocatalysts were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), electron spin resonance (ESR), X-ray photoelectron spectroscope (XPS) and Fourier transform infrared (FTIR) spectra. The results revealed that adsorbed hydroxyl group density significantly influenced the photocatalytic activity, and a small amount of Fe3+ can act as a photo-generated hole and a photo-generated electron trap and inhibit the electron–hole recombination. The 0.10%-Fe3+-TiO2 with the highest surface hydroxyl group density revealed the maximum rate constant of 0.716 and the optimal photocatalytic degradation of MB. As Fe3+ doping levels are larger than 0.10%, the cluster of Fe Ti ′ – V ¨ O – Fe Ti ′ generated gradually. This implied that an excessive amount of Fe3+ doped into TiO2 is detrimental to the photocatalytic activity due to the formation of Fe Ti ′ – V ¨ O – Fe Ti ′ clusters and enhances the recombination of photogenerated electrons and holes.

In this work, the chemical bulk diffusion coefficient ( D chem ) of SmBa 0.6 Sr 0.4 Co 2 O 5+ δ was determined by an electrical conductivity relaxation (ECR) method. The equation of D chem as a function of temperature in the range of 500–700 °C exhibits as follows: D chem = 1.77×10 −5 (−68.039 (kJ mol −1 )/ RT ) (m 2 s −1 ) Electrochemical impedance spectroscopy (EIS) technique was performed over the temperature range of 600–850 °C to determine the cathode polarization resistance ( R p ). The area specific resistances (ASR) of SmBa 0.6 Sr 0.4 Co 2 O 5+ δ -Ce 0.8 Sm 0.2 O 1.9 (70:30 in wt%) composite cathode were 5.16, 0.86 and 0.21 Ω cm 2 at the operating temperatures of 600, 700 and 800 °C respectively. The exchange current densities ( i o ) for oxygen reduction reaction (ORR) were determined from the EIS approach, and low-field and high-field cyclic voltammetry. The activation energies ( E a ) of ORR determined from the slope of Arrhenius plots for EIS, low-field and high-field technique were 148.6, 69.8 and 74.2 kJ mol −1 , respectively. Based on the electrochemical properties, the mixed-ionic-and-electronic conductor (MIEC) of SmBa 0.6 Sr 0.4 Co 2 O 5+ δ is a potential cathode for intermediate temperature solid oxide fuel cells (IT-SOFCs) based on a SDC electrolyte.

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.

This work reports the characteristics of Sm0.5Sr0.5CoO3−δ (SSC) cathode including its chemical bulk diffusion coefficient (Dchem), current density (i0), and single cell performance. In this study, the value of Dchem is measured by an electrical conductivity relaxation (ECR) technique. The equation of Dchem as a function of temperature in the range of 500–700 °C exhibits as follows: D chem = 4.65 × 10 − 5 exp ( − 91.33 ( kJ mol − 1 ) R T ) ( m 2 s − 1 ) To improve the cathode performance, the active ionic-conductive Ce0.8Sm0.2O1.9 (SDC) nanoparticles deposit on a porous SSC cathode surface by infiltration method. The enhancement in electrochemical performances is ascribed to the creation of electrolyte/cathode phase boundaries, which considerably increases the electrochemical sites for oxygen reduction reaction. In this work, the 0.2 M SDC-infiltrated SSC reveals the maximum peak power density of 489 mW cm−2 at operating temperature of 700 °C with a thin film SDC electrolyte (30 μm), a Ni + SDC anode (1 mm) and a SDC-infiltrated SSC cathode (20 μm).

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.

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.

The mixed ionic and electronic conductors of La 0.9 Ca 0.1 Ni 0.5 Co 0.5 O 3 –Ce 0.8 Sm 0.2 O 1.9 (LCNC–SDC) are investigated systematically for potential application as a cathode for solid oxide fuel cells based on a Ce 0.8 Sm 0.2 O 1.9 (SDC) electrolyte. The electrochemical impedance spectroscopy (EIS) measurements are performed in air over the temperature range of 600–850 °C to determine the cathode polarization resistance. The exchange current densities for oxygen reduction reaction (ORR), determined from the low-field cyclic voltammetry, high-field cyclic voltammetry, and EIS data are systematically investigated. The activation energies ( E a ) for ORR determined from the slope of Arrhenius plots are in the range of 102.33–150.73 kJ mol −1 for LCNC–SDC composite cathodes. The experimental results found that LCNC–SDC (70:30) composite cathode has a maximum exchange current density and a minimum polarization resistance of 0.30 Ω cm 2 for 850 °C among LCNC–SDC composite cathodes.

The mixed ionic and electronic conductors (MIECs) of Sm 0.5 Sr 0.5 Co 0.4 Ni 0.6 O 3−δ (SSCN)–Sm 0.2 Ce 0.8 O 1.9 (SDC) were investigated for potential application as a cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs) based on an SDC electrolyte. Electrochemical impedance spectroscopy (EIS) technique was performed over the temperature range of 600–850 °C to determine the cathode polarization resistance which is represented by area specific resistance (ASR). To investigate the ORR mechanism, the impedance diagram for 70SSCN–30SDC was measured under applied cathodic voltage from E = 0.0 to E = −0.3 V. It indicated that the charge transfer dominated the rate-determining step at the temperature of 600 °C; whereas the diffusion or dissociative adsorption of oxygen dominated the rate-determining step at the temperature of 800 °C. In this study, the exchange current density ( i 0 ) for oxygen reduction reaction (ORR) was determined from the EIS data. The i 0 value of 70SSCN–30SDC/SDC was 187.6 mA cm −2 which is larger than the i 0 value of 160 mA cm −2 for traditional cathode/electrolyte, i.e. LSM/YSZ at 800 °C, indicating that the 70SSCN–30SDC composite cathode with a high catalytically active surface area could provide the oxygen reduction reaction areas not only at the triple-phase boundaries but also in the whole composite cathode.

SmBaCo2O5+δ (SBC) was studied as cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The crystal structure, thermal expansion behavior, and electrochemical performance with long-term operation of SBC were characterized. An orthorhombic layered perovskite structure was observed in SBC cathode by a GSAS program for refinement. The average thermal expansion coefficient (TEC) is 21.6 x 10-6K-1 in the temperature range of 100oC-800oC. For long-term testing, the polarization resistance of SBC cathode increases gradually from 25.77 Ω cm2 for 2 h to 38.77 Ω cm2 for 96 h at 600°C, and an increasing-rate for polarization resistance is around 13,8% h-1. Based on the electrochemical properties, SBC cathode with mixed ionic and electronic conductor (MIEC) behavior is a potential cathode for intermediate temperature solid oxide fuel cells based on a SDC electrolyte.

In the current research, we proposed a new method called microwave-induced combustion synthesis to produce LiMn2O4 powders. The microwave-induced combustion synthesis entails the dissolution of metal nitrates, and urea in water, and then heating the resulting solution in a microwave oven. Spinel LiMn2O4 powders were successfully synthesized by microwave-induced combustion. The microwave-heated LiMn2O4 powders annealed at various temperatures in the range of 600–800 °C were determined. The resultant powders were characterized by X-ray diffractometer (XRD), and scanning electron microscopy (SEM). The annealed samples were used as cathode materials for lithium-ion battery, for which their discharge capacity and electrochemical characteristic properties in terms of cycle performance were also investigated. The LiMn2O4 cell provides a high initial capacity of 133 mAh/g and excellent reversibility. The excellent capacity and reversibility were attributed to LiMn2O4 powders with small and uniform particle size produced by microwave-induced combustion synthesis.

An aqueous tape casting of gadolinia-doped ceria (GDC) ceramics was developed using Poly(acrylic acid) PAA as dispersant, Poly(vinyl alcohol) PVA as binder, Poly(ethylene glycol) PEG as plasticizer, and deionized water as solvent. Surface properties of GDC powder with and without PAA dispersant were characterized by electrokinetic measurements. The zeta potential measurement revealed that the isoelectric point for GDC powders in the absence of dispersant corresponds to a pH value of 4.06. The experimental results showed that pH value greatly affects the rheology of the slurry. Homogeneous, smooth, and defect-free green tapes were successfully obtained by using an appropriate slurry formula. Moreover, the crystallization kinetics of GDC powders prepared by coprecipitation process also has been investigated in this study. The activation energy of crystallization was calculated by differential scanning calorimetry (DSC) at different heating rates. Analysis of non-isothermal DSC data presented values of 105.3 kJ/mol and 1.171 for the activation energy of crystallization presented and the Avrami exponent, respectively.

A non-isothermal study of the crystallization kinetic of coprecipitation of Bi 1.25 Y 1.75 Fe 5 O 12 was carried out by differential scanning calorimetry (DSC). The Avrami exponent n suggesting the dimensionality of crystal growth was determined using the Ozawa equation. From non-isothermal DSC data presented values in range of 775–1023 kJ/mol and 3.28–2.10 for the activation energy of crystallization and the Avrami exponent, respectively. These Avrami exponent values were consistent with surface and internal crystallizations growth simultaneously.

Olivine structured LiFePO 4 (lithium iron phosphate) and Ti 4+ -doped LiFe 1− x Ti x PO 4 (0.01 ≤ x ≤ 0.09) powders were synthesized via a solution route followed by heat-treatment at 700 °C for 8 h under N 2 flowing atmosphere. The compositions, crystalline structure, morphology, carbon content, and specific surface area of the prepared powders were investigated with ICP-OES, XRD, TEM, SEM, EA, and BET. Capacity retention study was used to investigate the effects of Ti 4+ partial substitution on the intercalation/de-intercalation of Li + ions in the olivine structured cathode materials. Among the prepared powders, LiFe 0.97 Ti 0.03 PO 4 manifests the most promising cycling performance as it was cycled with C/10, C/5, C/2, 1C, 2C, and 3C rate. It showed initial discharge capacity of 135 mAh g −1 at 30 °C with C/10 rate. From the results of GSAS refinement for the prepared samples, the doped-Ti 4+ ions did not occupy the Fe 2+ sites as expected. However, the occupancy of the doped Ti 4+ ions are still not clear, and theoretical calculations are needed for further studies. From the variation of lattice parameters calculated by the least square method without refinement, it suggested that Ti 4+ -doped LiFePO 4 samples formed solid solutions at low doping levels while TiO 2 was also observed with TEM in samples prepared with doping level higher than 5 mol%.

The non-isothermal crystallization kinetics of Bi0.75Y2.25Fe5O12 powder prepared by coprecipitation has been investigated. The activation energy of crystallization was calculated by differential scanning calorimetry (DSC) at different heating rates. Analysis of non-isothermal DSC data presented values of 650 kJ/mol and 2.48 for the activation energy of crystallization and the Avrami exponent, respectively. This Avrami exponent value was consistent with surface and internal crystallizations occurring simultaneouly. The complex permittivity and permeability of Bi0.75Y2.25Fe5O12 were measured at X-band (8–12 GHz) by cavity perturbation technique. For dielectric properties, the real part of permittivity, ɛ′, was obtained in the range of 13.18–15.28. For magnetic properties, the real part of permeability, μ′, was obtained in the range of 12.21–20.98.

An aqueous tape casting of Ce 0.8 La 0.2 O 1.9 (LDC) ceramics was developed using PAA as dispersant, PVA as binder, PEG as plasticizer, and deionized water as solvent. Surface properties of LDC powder with and without PAA dispersant were characterized by electrokinetic measurements. The rheology of the LDC slurries was evaluated with a rotary viscometer. The zeta potential measurement showed that the isoelectric point for LDC powders in the absence of dispersant corresponds to a pH value of 4.02. The experimental results showed the pH value greatly affects the rheology of the slurry. The optimum content to get a stable dispersed slurry is 1.5 wt% PAA at pH value of 9–10. In presence of 1.5 wt% PAA dispersant, 5 wt% PVA binder, 5 wt% PEG plasticizer, and 55 wt% LDC powders exhibited shear thinning behavior, indicating that LDC slurry was homogenous and well stabilized. With an appropriate formulation homogeneous, smooth, and defect-free green tapes were successfully obtained. Moreover, the crystallization kinetics of LDC powders prepared by coprecipitation process also has been investigated in this study. The activation energy of crystallization was calculated on the basis of differential scanning calorimetry (DSC) at different heating rates. From non-isothermal DSC data presented values in the range of 343.3–379.1 kJ/mol and 2.282–2.030 for the activation energy of crystallization and the Avrami exponent, respectively, at specific temperatures ranging from 280 to 285 °C.

Copper ferrite nano-particles with Fe/Cu ratios varying from 2 to 12 were successfully synthesized by combustion process using copper nitrate, iron nitrate and urea. The resultant powders were investigated by scanning electron microscopy (SEM), vibrating sample magnetometer (VSM). The results revealed that the copper ferrite powders are uniform in the range of 250-300 nm. The copper ferrite with Fe/Cu ratio of 2 possessed a saturation magnetization of 5.47 emu/g, and an intrinsic coercive force of 241.98 Oe, with Fe/Cu ratio of 12 possessed a saturation magnetization of 22.06 emu/g and an intrinsic coercive force of 247.94 Oe. Moreover, these copper ferrite magnetic nano-particles also acted as catalyst for the oxidation of 2,3,6-trimethylphenol to synthesize 2,3,5-trimethylhydrogenquinone and 2,3,5-trimethyl-1,4-benzoquinone for the first time. The conversion of 2,3,6-trimethylphenol in the kinetic behavior of oxidation was investigated in detail. The reaction shows dramatically enhanced by the addition of copper-ferrite nano-particles to the solution.

The non-isothermal crystallization kinetics of Bi0.25Y2.75Fe5O12 powder prepared by the coprecipitation process has been investigated. The activation energy of crystallization was calculated by differential scanning calorimetry (DSC) at different heating rates. From non-isothermal DSC data presented values in the range of 712–772 kJ/mol and 2.90–3.46 for the activation energy of crystallization and the Avrami exponent, respectively at specific temperature ranging form 750.0 to 757.5 °C. This value for the Avrami exponent indicates that the controlling mechanism of crystallization is three-dimensional interfacial growth.

An aqueous tape casting of Ce0.8Y0.2O1.9 (YDC) ceramics was developed using poly(acrylic acid) (PAA) as a dispersant, poly(vinyl alcohol) (PVA) as a binder, poly(ethylene glycol) (PEG) as a plasticizer, and deionized water as a solvent. The surface properties of YDC powder with and without PAA dispersant were characterized by zeta potential. The rheological of the YDC slurries was evaluated with a rotary viscometer. The zeta potential measurement showed that the isoelectric point for YDC powders in the absence of dispersant had a pH value of 3.35. The experiment results showed that the pH value greatly affects the rheology of the slurry. In the presence of 2 wt % PAA dispersant, 55 wt % YDC powders exhibited shear thinning behavior, indicating that YDC slurry was homogenous and well stabilized. With an appropriate formulate, homogeneous, smooth, and defect-free green tapes were successfully obtained. Moreover, the crystallization kinetics of YDC powders prepared by the coprecipitation process has also been investigated in this study. The activation energy of crystallization was calculated on the basis of differential scanning calorimetry (DSC) at different heating rates. The activation energy of crystallization presented a value of 192.8 kJ/mol.

The nonisothermal crystallization kinetic of BixY3−xFe5O12 (0.25≤x≤1.00) powders prepared by coprecipitation process has been investigated. The activation energy of crystallization was calculated by differential scanning calorimetry at different heating rates. The activation energies of crystallization of BixY3−xFe5O12 system are 492, 447, 377, and 353 kJ/mol and the Avrami constant n are 3.49, 2.25, 2.48, and 2.33 for x=0.25, 0.50, 0.75, and 1.00, respectively. The Avrami exponent values (1 3) for the Avrami exponent was consistent with bulk crystallization domination in BixY3−xFe5O12 system. The results reveal that increasing the substitution amount of bismuth for yttrium would significantly decrease activation energy in BixY3−xFe5O12 system.

The crystallization kinetics of Bi0.5Y2.5Fe5O12 powders prepared by the coprecipitation process have been investigated. The activation energy of crystallization was calculated on the basis of differential scanning calorimetry at different heating rates. Analysis of nonisothermal DSC data yielded a value of 823.8 kJ/mol and 2.25 for the activation energy of crystallization and the Avrami exponent, respectively. This value for the Avrami exponent was consistent with surface and internal crystallization occurring simultaneously. The complex permittivity and permeability of Bi0.5Y2.5Fe5O12 was measured at the X-band (8–12 GHz) using the cavity perturbation technique. For dielectric properties, the real part of permittivity, ɛ′, was obtained in the range of 13.57–16.37. For magnetic properties, the real part of permeability, μ′, was obtained in the range of 21.61–16.90.

The non-isothermal crystallization kinetics of Bi1.0Y2.0Fe5O12 powder prepared by coprecipitation has been investigated. The activation energy of crystallization was calculated by differential scanning calorimetry (DSC) at different heating rates. Analysis of non-isothermal DSC data presented values of 634 kJ/mol and 2.33 for the activation energy of crystallization and the Avrami exponent, respectively. This Avrami exponent value was consistent with surface and internal crystallizations occurring simultaneously. The complex permittivity and permeability of Bi1.0Y2.0Fe5O12 were measured at X-band (8–12 GHz) by cavity perturbation. For dielectric properties, the real part of permittivity, e', was obtained in the range of 13.44–15.26. For magnetic properties, the real part of permeability, µ', was obtained in the range of 21.39–12.17.

Spinel LiMn1.925M0.075O4 (M = Cr, Co) powders with small and uniform particle size were successfully synthesized by microwave-induced combustion. The LiMn1.925M0.075O4 (M = Cr, Co) samples were used as cathode materials for lithium-ion battery, which their discharge capacity and electrochemical characteristic properties were investigated in this study. The results revealed that The Li/LiMn1.925M0.075O4 (M = Cr, Co) cells showed lower capacity loss than Li/LiMn2O4 cell after 30 cycles. Moreover, Cr-substituted spinel exhibited a lower capacity loss than Co-substituted spinel. The initial capacity of LiMn2O4 and LiMn1.925M0.075O4 cells can be ranked as follows: LiMn2O4 > LiMn1.925Cr0.075O4 > LiMn1.925Co0.075O4.

Barium ferrite powders were successfully synthesized by a microwave-induced combustion process. The process takes only a few minutes to obtain calcined barium ferrite powders. The resultant powders were investigated by XRD, SEM, VSM, TG/DTA, and a surface area measurement. The as-received product shows the barium ferrite with saturation magnetization ( M s )≈23 emu/g and an intrinsic coercive force ( i H c ) of 595 Oe, whereas upon annealing at 1000 °C for 2 h, the saturation magnetization ( M s ) increases to 66 emu/g and the intrinsic coercive force ( i H c ) reaches 2100 Oe.

Spinel LiMn 2 O 4 powders with small and uniformly sized particle were successfully synthesized by microwave-induced combustion, using lithium nitrate, manganese nitrate, and urea as the staring materials. LiMn 2 O 4 powders were investigated by X-ray diffractometer (XRD), and scanning electron microscopy (SEM). LiMn 2 O 4 samples were used as cathode materials for lithium-ion battery, whose discharge capacity and electrochemical characteristic properties in terms of cycle performance were also discussed. The results revealed that the Li/LiMn 2 O 4 cell synthesized by microwave-induced combustion had a high initial capacity and much better reversibility than one formed in a solid-state reaction.

The solid-state reaction route was successfully used to prepare (Ba,Sr)O–Al 2 O 3 –2SiO 2 ceramics. Firstly, the mixed powder was characterized by differential thermal analysis and thermogravimetric analysis. The ceramics powder was obtained by calcining a BaCO 3 , SrCO 3 , Al 2 O 3 , and SiO 2 mixture at 950 °C for 4 h. Secondly, the calcined powder was pressed, sintered at 1040 °C for 4 h, Then the sintered samples were investigated by X-ray diffraction, scanning electron microscopy, density measurement, and thermal mechanical analyzer. In this work, the appropriate addition of SrO was observed to enhance the hexacelsian to celsian transformation. Additionally, the appropriate addition of SrO effectively reduced the thermal expansion coefficient of the (Ba,Sr)O–Al 2 O 3 –2SiO 2 ceramics.

Barium ferrite powders were successfully synthesized by microwave-induced combustion. The magnetic properties of barium ferrite powders with various Fe/Ba ratios varying from 11 to 12 annealed at various temperatures in the range of 850–1050°C were determined. The resultant powders were investigated by X-ray diffractometer (XRD), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), differential thermal analyzer/thermogravimeter (DTA/TG), and surface area measurement. Microwave-heated barium ferrite with an Fe/Ba ratio of 11 and annealed at 1000°C for 2 h exhibited optimum magnetic properties for magnetic recording applications, a saturation magnetization of 66 emu/g and an intrinsic coercive force of 2100 Oe. The microwave-heated barium ferrite powders with various Fe/Ba ratios annealed at various temperatures had particles size ranging from 40 to 90 nm. Thus, the fine control of crystal growth by varying the annealing temperature can be exploited for the production of fine magnetic powders of various sizes for a variety of practical applications.

Strontium hexaferrite powders were successfully synthesized by a microwave-induced combustion process. The process only took a few minutes to obtain calcined strontium hexaferrite powders. The resultant powders were investigated by XRD, TEM, VSM, TG/DTA, and surface area measurement. The as-received product shows strontium ferrite with a saturation magnetization (Ms) of ≈38 emu/g and an intrinsic coercive force (iHc) of 525 Oe, whereas, upon annealing at 1000 °C for 2 h, the saturation magnetization increases to 62 emu/g and the intrinsic coercive force reaches 1950 Oe.

The synthesis and microwave characterization of glass ceramic in the quaternary phase field of the MgO-CaO-Al2O3-SiO2 system synthesized by sol-gel method have been investigated in this paper. The glass powder was obtained by calcining the MgO-CaO-Al2O3-SiO2 xerogel, which was prepared from Magnesium nitrate hexahydrate (Mg(NO3)2·6H2O), Aluminum nitrate nonahydrate (Al(NO3)3·9H2O), Calcium nitrate tetrahydrate (Ca(NO3)2·4H2O), and tetraethylortho silicate (TEOS). The powder was characterized by differential thermal analysis, thermogravimety and X-ray diffraction. The calcined powder was pressed, sintered at different temperatures, and then the sintered sample was studied with scanning electron microscope, X-ray diffraction patterns, and microwave properties measurement.

Ni–Zn ferrite powders were successfully synthesized by microwave-induced combustion process. The process takes only a few minutes to obtain calcined Ni–Zn ferrite powders. The resultant powders were investigated by XRD, SEM, VSM, TG/DTA and surface area measurements. The as-received product shows the formation of cubic ferrite with saturation magnetization ( M s )≈23 emu/g, whereas upon annealing at 850°C for 4 h, the saturation magnetization ( M s ) increased to ≈52 emu/g.

CIGS polycrystalline thin films were successfully fabricated by one-step cathodic electrodeposition on Mo-coated glass. In this study, we applied a galvanometry mode with three-electrode potentiostatic systems to produce a constant concentration electroplating solution, which were composed of CuCl2, InCl3, GaCl3, and SeO2. Then these as-electrodeposited films were annealed in argon atmosphere and characterized by X-ray diffraction. The results revealed that annealing treatment significantly improved the crystallinity of electrodeposited films and formed CIGS chalcopyrite structure, but at low applied deposition voltage (−950 mV versus SCE) there appeared second phase. The cross-section morphology revealed that applied voltage at −1350 mV versus SCE has uniform deposition, and higher applied voltage made grain more unobvious. The deposition rate and current density are proportional to deposition potential, and hydrogen was generated apparently when applying potential beyond −1750 mV versus SCE. It was found that the CIGS compound did not match exact stoichiometry ofCu : In : Ga : Se =1 : x : 1-x : 2. This result suggests the possibility of controlling the property of thin films by varying the applied potential during electrodeposition.

A single phase of CuIn 1-x Ga x Se 2 (CIGS) polycrystalline thin films was successfully fabricated by the pulse-reverse electrodeposition technique. In this study, a multipulse sequence of potentials with varying amplitude and duration time was used to fabricate CIGS thin film, in which the electrolyte was composed of CuCl 2 , InCl 3 , GaCl 3 , SeO 2 , Na-citric, and LiCl. Then these as-deposited films were annealed in argon atmosphere. The crystalline structure of the thin film was characterized by X-ray diffractometer. The results revealed that thin films fabricated by the pulse-reverse electrodeposition technique only produced a chalcopyrite structure, with no occurrence of Cu 2-x Se secondary phases. The identification of Cu 2-x Se secondary microcrystalline phases and vibration modes of chalcopyrite and Cu 2-x Se was used by a micro-Raman spectrum. The morphological features were characterized by scanning electron microscopy, which showed that the films were dense and smooth compared with that fabricated by a one-step electrodeposition technique without a multipulse step. The thickness and roughness of the CIGS thin films were estimated by an Alpha-Step profilometer. Finally, the carrier type of the CIGS thin film is of a p-type nature as confirmed by electrochemical measurement.