Fuel cells are at the forefront of modern energy research, with graphene-based materials emerging as key enhancers of performance. This overview explores recent advancements in graphene-based cathode materials for fuel cell applications. Graphene’s large surface area and excellent electrical conductivity and mechanical strength make it ideal for use in different solid oxide fuel cells (SOFCs) as well as proton exchange membrane fuel cells (PEMFCs). This review covers various forms of graphene, including graphene oxide (GO), reduced graphene oxide (rGO), and doped graphene, highlighting their unique attributes and catalytic contributions. It also examines the effects of structural modifications, doping, and functional group integrations on the electrochemical properties and durability of graphene-based cathodes. Additionally, we address the thermal stability challenges of graphene derivatives at high SOFC operating temperatures, suggesting potential solutions and future research directions. This analysis underscores the transformative potential of graphene-based materials in advancing fuel cell technology, aiming for more efficient, cost-effective, and durable energy systems.

The 0.5(BiGd_0.05Fe_0.95O₃)-0.5(PbZrO₃) composite was synthesized by means of a high temperature solid-state reaction technique using high purity ingredients. Preliminary X-ray structural analysis confirms the formation of the composite. The dielectric constant and loss tangent have been studied. The impedance parameters have been measured using an impedance analyzer in a wide range of frequency (10²–10⁶ Hz) at different temperatures. The Nyquist plot suggests the contribution of bulk effect only and the bulk resistance decreases with a rise in temperature. Electrical impedance confirms the presence of grain effect and hopping mechanism in the electrical transport of the material. The dc conductivity increases with a rise of temperature. The frequency variation of ac conductivity shows that the compound obeys Jonscher’s universal power law and from Jonscher’s power law fit confirms the Small Polaron (SP) tunneling effect. Temperature dependence of dc and ac conductivity indicates that electrical conduction in the material is a thermally activated process.

Background: Lithium Niobate (LiNbO3) is a ferroelectric material suitable for a variety of applications. Its versatilityis made possible by the excellent electro-optic, nonlinear, and piezoelectric properties of the intrinsic material. Objective: Study of structural, microstructural and electrical propertiesare to understand the structure and topography of the composites. Methods: The sample of LiNbO3 was prepared by solid state reaction method at high temperature using high purity ingredients. Results: The analysis of the X-ray diffraction at room temperature confirmed the trigonal structure. The grains are more or less homogeneously distributed throughout the surface. The dielectric constant and dielectric loss are decreases with increase in frequency. The material has high dielectric constant and low dielectric loss at room temperature. The magnitude of real impedance decreases with rise in temperature which shows negative temperature coefficient of resistance behavior.The nature of the conductivity in solids is analyzed which obeyed Jonscher’s power law. The temperature-dependence of dc conductivity indicates that the electrical conduction in the material is a thermally activated process. Conclusion: The compound exhibits a dielectric anomaly at high temperature suggesting ferroelectric–paraelectric phase transition. The activation energy of the material is found to be 0.00184 eV in the high temperature region of Arrhenius plot for electrical conductivity. The nature of temperature dependence of the dc conductivity exhibited the NTCR behaviour of the material.

This paper discusses the temperature and frequency-dependent dielectric and electrical transport properties of cobalt ferrite (CoFe₂O₄) and its suitability for thermistor applications. The material is prepared through a high-temperature solid-state reaction route. The formation of the materials is checked by using an X-ray diffraction. Microstructure study is done through SEM analysis. Analysis of dielectric data shows a thermally activated relaxation process occuring in the material within the studied frequency range. Analysis of complex impedance (Nyquist) plots at different temperatures reveal the contribution of grain to the overall electrical response of the compound. The variation of dc conductivity with temperature shows the NTCR behavior of the material. Looking into the strong dependence of resistivity on temperature, the thermistor parameters are evaluated using the grain resistance at different temperatures, which suggest the possible application for thermistor-based devices as well as a temperature sensor. The temperature-dependent ac conductivity (σ _ac) fits well with Jonscher’s universal power law. The activation energy calculated from the temperature-dependent spectroscopic plots of impedance and conductivity suggests the charge carriers involved in deciding transport properties.