The rapid growth of renewable energy integration and electrified transportation has intensified the need for innovative energy storage systems, with solid-state batteries (SSBs) emerging as a potential solution owing to their high energy density, enhanced safety, and long cycle life. Catholyte materials are central to the performance of SSBs, serving dual roles as cathodes and electrolytes, and influencing ion transport, interfacial stability, and overall battery efficiency. The current review comprehensively explores the advanced catholyte materials, centering on oxide-, sulfide-, halide-, and polymer-based systems, alongside composite designs. The ionic conductivity, electrochemical stability, redox properties, and mechanical integrity, highlighting the advancements in synthesis techniques, defect engineering, and nanotechnology integration have been explored. Key challenges, such as interfacial resistance, scalability, and sustainability, are critically assessed, with an emphasis on emerging strategies, such as interface engineering and computational high-throughput screening, to overcome these barriers. By elucidating the structure-property relationships and future research directions, this review underscores the pivotal role of catholyte optimization in realizing commercially viable SSBs, offering a roadmap for nextgeneration energy storage technologies with superior performance and environmental compatibility.

This chapter provides a detailed examination of electrochemical cells, starting with the basic concepts of half-cells, reactions at equilibrium, and cell potential. It classifies electrochemical cells as galvanic and electrolytic cells and also includes new technologies like fuel cells and supercapacitors. The mechanism of electron transfer and comparison of cell types is highlighted. The applications portion ventures into classical applications, exploring electrochemical CO2 capture and reduction (ECCR), additive manufacturing, biosynthetic materials, and polymer electrosynthesis. There is a dedicated section on batteries with both conventional systems such as lead-acid and lithium-ion and biofuel and polymer-based derivatives. In addition, the chapter explores how energy density in electrochemical systems is controlled by cell voltage, capacity, and design parameters. Extensive focus is provided to electrodeposition methods throughout metals, alloys, semiconductors, and nanostructures, with ensuing extensive discussions on dimensional control, 2D/3D conformality, and nucleation and growth processes. Parametric factors such as temperature, pH, geometry, and pressure are extensively discussed, providing readers with a synoptic perception of both theory and new applications. The chapter emphasizes the central role of electrochemical systems in meeting current scientific, industrial, and energy challenges.

The automotive sector contributors (20–30) % to global greenhouse gas emissions, posing a significant challenge to achieving sustainable energy transitions. Electric vehicles (EVs), powered by advanced battery energy storage systems (BESS), have emerged as the most viable alternative to conventional internal combustion engine (ICE) vehicles. However, the performance, safety, and lifespan of these batteries are highly sensitive to temperature variations, necessitating efficient thermal management strategies. This review provides a comprehensive analysis of recent developments in automotive battery cooling systems covering air, liquid, phase change material (PCM), thermoelectric, and nanoparticle-assisted technologies and evaluates their effects on system performance, energy efficiency, and environmental sustainability. Furthermore, this review examines how improved thermal management indirectly contributes to reducing carbon emissions and resource consumption through extended battery life and reduced material waste. The discussion also aligns these findings with the United Nations Sustainable Development Goals (SDGs) 7, 8, 9, 11, and 12, highlighting the broader socio-environmental implications of adopting advanced battery cooling systems in the transition toward cleaner mobility.

Ceria co-doped with Ni and Mg (Ni, Mg@CeO2) was examined for its electrochemical performance, showing impressive power density and cyclic stability in the fabricated device. The material was synthesized using an easy, low-cost solution combustion method. Two different materials were studied to evaluate the impact of co-doping: pristine CeO2/AC (M-1) and Ni, Mg@CeO2 composite with AC (Activated Carbon) (M-2). Structural analysis confirmed the face-centered cubic (FCC) structure of CeO2 through X-ray diffractometry (XRD). The structural and optical properties were characterized by using field-emission scanning electron microscopy (FESEM) and photoluminescence (PL) spectroscopy, respectively. The electrochemical behavior was tested with cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS), revealing the pseudocapacitive nature of the ceria-based electrodes. As an electrode material, CeO2/AC (M-1) achieved a higher specific capacitance (Cs) of 244.4 F/g at 0.5 A/g, while Ni, Mg@CeO2/AC (M-2) showed 197.6 F/g at the same current. In a full-device setup, Ni, Mg@CeO2//AC (M-2) reached a Cs of 63.3 F/g at 0.5 A/g, along with excellent cycling stability, retaining 100.4% coulombic efficiency over 5000 GCD cycles. The hybrid device based on Ni, Mg@CeO2//AC displayed a maximum specific energy of 18.3 Wh/kg and a specific power of 467.5 W/kg at 0.5 A/g.

In the field of supercapacitors, carbide MXenes have recently received significant attention as pseudocapacitive electrode materials due to their unique multilayered structure, high metallic conductivity, pseudocapacitive charge storage mechanism and tunable surface terminations. Herein, synthesis and electrochemical performance of 2D molybdenum carbide (Mo2C) MXene-based electrode is presented for supercapacitor applications. Mo2C MXene was synthesized by using simple solid-state thermal reduction technique. The crystalline structure, surface morphologies, specific capacitance, electronic conductivity and reaction kinetics of as-synthesized Mo2C MXene were examined using XRD (X-ray diffraction) analysis, FESEM (field emission scanning electron microscopy), CV (cyclic voltammetry) and EIS (electrochemical impedance spectroscopy) measurements, respectively. The hexagonal phase (with P63/mmc symmetry) of Mo2C MXene was confirmed by XRD analysis. The 2D multilayered structure was displayed by FESEM results. The cyclic voltammograms revealed an efficient electrochemical performance of 2D Mo2C MXene. Due to its high current density, large surface area and abundance of redox acive sites, MXene-based electrode displayed high specific capacitance of 916 F/g at 5 mV/s. Further, excellent electronic conductivity and minimum charge transfer resistance was observed by EIS plots. The significant electrochemical performance of Mo2C MXene-based electrode governs its implementation for developing highly efficient supercapacitors with high energy and power densities.

The current work pioneers the synthesis of a novel composition of Sr0.9X0.1CoO3-delta (X = Ba, Ce) perovskite electrode materials for supercapacitors through an innovative semi-green route, utilizing lemon powder as the bio-chelating agent. The synergy between the biomolecules and organic citric acid in lemon powder resulted in minimal impurities and enhanced the crystallinity of the desired perovskite electrodes. XRD analysis confirmed the cubic perovskite structure of all Sr0.9X0.1CoO3-delta (X = Ba, Ce) perovskite electrodes synthesized via both semi-green and chemical approaches. Notably, samples synthesized through the semi-green approach exhibited better crystallinity with no secondary phases. Microstructural analysis revealed a dense and agglomerated morphology for all samples, while EDX analysis confirmed the elemental composition with no prominent impurities. FTIR analysis confirmed the presence of identical functional groups in samples synthesized through both routes. Electrochemical studies demonstrated the highest specific capacitance of 1176.36 F g-1 and excellent electrochemical stability, with 88.2% capacity retention after 5000 galvanostatic charge-discharge cycles for Sr0.9X0.1CoO3-delta (X = Ce) synthesized through the semi-green route. Meanwhile, Sr0.9X0.1CoO3-delta (X = Ba) also exhibited a reasonable specific capacitance. These findings confirm that the novel perovskite composition Sr0.9X0.1CoO3-delta (X = Ba, Ce) can be successfully utilized for supercapacitor applications and that the innovative semi-green route can also be employed for the efficient synthesis of perovskite materials, ensuring minimal ecological impact and reduced impurities compared to conventional chemical and green synthesis routes.

Supercapacitors are required to store energy from renewable resources to ensure a pollutant-free environment. To further encourage its study, researchers are interested in introducing green methods to produce electrode materials. Green synthesis is an innovative and emerging field because plant extracts are the best substitute for toxic chemicals. They are considered eco-friendly and cost-effective. In this work, two plant extracts, orange juice (ORJ) and lemon juice (LMJ), are used to synthesize the Sr0.8Ce0.2Fe0.8Co0.2O3 perovskite using the auto-combustion method. The electrochemical performance of Sr0.8Ce0.2Fe0.8Co0.2O3 made from LMJ and ORJ is compared to check their effectiveness. LMJ proved to be a better reducing agent than ORJ with a higher specific capacity of 300 C/g (544 F/g) at 1 A/g current density due to increased oxygen vacancies and surface area. These findings show that green-synthesized perovskites can be utilized in high-performance hybrid supercapacitor devices.

The development of efficient and environmentally sustainable anode materials is essential for advancing solid oxide fuel cells (SOFCs). In this study, we introduced a pioneering green synthesis approach utilizing spinach leaves powder as a bio-derived chelating agent, alongside a conventional chemical route using oxalic acid, to synthesize Ni-BZr0.8Y0.1X0.1O3-δ (Ni-BZYX; X = Co, Mn) perovskite-based anodes. This eco-friendly method leverages natural, renewable spinach powder to reduce the environmental footprint of material synthesis, offering a sustainable alternative to traditional chemical processes. Structural characterization via XRD and FTIR confirmed the formation of single-phase cubic perovskite structures without secondary phases, demonstrating effective doping and phase stability in both synthesis routes. SEM analysis revealed that oxalic-acid-synthesized samples exhibited superior porosity, reduced particle agglomeration, and enhanced microstructural uniformity, facilitating efficient gas diffusion and expanding the electrochemically active triple-phase boundary (TPB). Electrochemical testing at 650 °C demonstrated that Ni-BZYCo (oxalic acid) delivered the highest power density of 0.56 W cm-2. Although greenly synthesized anodes exhibited slightly lower performance due to minor residual impurities, the spinach-based approach represents a significant advancement toward sustainable SOFC materials with comparable structural and functional properties. This work underscores the environmental and practical potential of bio-derived synthesis strategies and positions Co-doped Ni-BZY as a high-performance anode for sustainable SOFC technologies.

The development of an optimal material that facilitates multiple redox reactions is crucial for advancing energy storage devices. In the present study, we focused on preparing such a material through an easy and cost-effective method to achieve enhanced charge storage ability with large power. Multiphase composites based on Mn, Ce, Co, and Ni oxides were prepared via solution combustion synthesis (SCS) for supercapacitor electrode applications. Three composites, Mn-O/CeO2 (N1), Ni-O/Co3O4 (N2), and Mn-O/CeO2/Ni-O/Co3O4 (N3), all in equal ratios, were prepared after sintering at 700 degrees C for 3 h in the open air. Preliminary characterizations, including Xray diffraction (XRD), diffuse reflectance spectroscopy (DRS), Raman spectroscopy, and scanning electron microscopy (SEM), were performed to investigate the structural, optical, and morphological properties of the three distinct composites. XRD analysis confirmed the presence of various phases, such as CeO2, Mn2O3, Co3O4, NiO, Ni2O3, and Mn5O8 in the different composites, significantly influencing their physical and electrochemical behavior. With three-electrode assembly, electroanalytical tools such as cyclic voltammetry (CV), galvanic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) were utilized to divulge electrochemical properties which confirmed pseudocapacitive behavior in the synthesized electrode composites. The specific capacitance of 59.3 F/g, 91.67 F/g, and 23.14 F/g at a current density of 1 A/g were recorded for N1, N2, and N3, respectively. Having tempting results of N2 cathode, it was fabricated against activated carbon (AC) anode to form a hybrid supercapacitor device which demonstrated a specific capacitance of 78.25 F/g, a specific energy of 24.45 Wh/kg, and a large specific power of 1086.80 W/kg at 1 A/g current density, with a coulombic efficiency of 106.5% over 1000 GCD cycles.

A multiphase composite system AgCo3O4/FeMn-O was synthesized using an easy and low-cost solution combustion method for supercapacitor application. The multiphase composite system consisting of Co3O4, alpha-MnO2, and Mn5O8 was identified by X-ray diffraction analysis. The phases were observed as settled on each other in the form of large spherical and hair-like formations in morphological images obtained from scanning electron microscopy. UV-VIS spectroscopy supported the results of variation of band gap energies of Co3O4, alpha-MnO2, and Mn5O8 due to Ag and Fe. Based on Raman spectroscopy, characteristic modes of Co3O4, alpha-MnO2, and Mn5O8 were observed. In electrochemical analysis, the cyclic voltammetry (CV) confirmed the intercalation typepseudocapacitive nature of the prepared composites. Galvanostatic charge-discharge (GCD) analysis showed the highest specific capacitance of 904 F/g obtained from one of the composites at 1 A/g current density. The supercapacitor device was fabricated and showed remarkable cyclic stability of 89 % even after 5000 GCD cycles along with 11.5 Wh/kg energy density and 522 W/kg power density. The good electrochemical performance was attributed to the multiple redox reactions occurred in the bulk of electrode material. Hence, the solution combustion method provides an easy and cost-effective approach to synthesize metal-oxide composites for super- capacitor applications.

This study examines the impact of leaching with dilute hydrochloric acid solution on the reduction of ash content and the thermal degradation behavior of sugarcane bagasse. Response surface methodology (RSM) was used to statistically design the experiments and investigate the effect of three independent variables: treatment time, solid-to-liquid ratio, and reagent concentration. The leaching conditions were further optimized and experimentally validated for maximum ash reduction for suitability of treated biomass as feedstock for thermochemical conversion technologies. Reagent concentration and treatment time directly affected ash reduction, while the solid-to-liquid ratio inversely influenced it. Concentration had the highest impact, and treatment duration had the least. The maximum 78.2% ash reduction was achieved by treating the biomass with 1 M HCl for 80 min at a solid-to-liquid ratio of 50:1 (wt/vol). This ash reduction also resulted in a 9.82% increase in higher heating value (HHV). Hemicellulose hydrolysis during leaching was observed through chemical composition and Fourier-transform infrared spectroscopy (FTIR). Ash fusion temperatures increased, indicating more thermally stable biomass. Thermogravimetric analysis (TGA) showed elevated maximum degradation temperature and activation energy.

A novel semi-organic combustion approach using orange and lemon juice as chelating agents is employed to synthesize the perovskite Sr(0.8)X(0.2)Co(0.2)Fe(0.8)O3-delta (x = La, Ce) cathode for IT-SOFCs. This approach has been found to exhibit lower toxicity compared to chemical routes and lower impurities compared to green routes. The structural analysis validated the successful synthesis of perovskite Sr0.8X0.2Co0.2Fe0.8O3-delta (La, Ce) cathode materials with no prominent secondary phase of impurities while surface morphology revealed a porous and well-connected network of particles. EDS confirmed the composition and thermo-gravimetric analysis showed weight losses related to the creation of vacancies. The functional groups were investigated through FTIR and the conductivity measurements revealed higher electrical conductivity for Sr0.8X0.2Co0.2Fe0.8O3-delta (x = La, Ce) synthesized with orange juice as a chelating agent with Sr0.8La0.2Co0.2Fe0.8O3-delta exhibiting slightly higher value compared to Sr0.8Ce0.2Co0.2Fe0.8O3-delta. The electrochemical performance showed the highest power density of 354 and 313 mW.cm(-2) at 700 degrees C obtained for cells having Sr0.8X0.2Co0.2Fe0.8O3-delta (x = La, Ce) cathodes synthesized with orange juice which was attributed to better crystallinity and uniform lattice. This work shows that a novel emi-organic route is successfully employed to synthesize the perovskite cathode materials for IT-SOFCs.

Zinc oxide-based nanomaterials (ZONMs) are of significant scientific and industrial interest due to their unique properties, versatility, and cost-effectiveness. This review comprehensively summarizes the potential applications of ZONMs across numerous fields, including dye-sensitized solar cells, the concrete and rubber industries, optoelectronics, gas sensing, the cosmetic industry, the textile industry, antibacterial activity, drug delivery, anticancer activity, antidiabetic activity, immunotherapy, anti-inflammatory activity, agriculture, and photodegradation. The review begins with an overview of ZONMs, highlighting their physical and structural properties. Subsequently, it discusses the applications of ZONMs in the aforementioned fields, emphasizing their outstanding performance and potential for commercialization. Additionally, the review explores the literature where ZONMs have been synthesized using various methods. It provides insights into the fabrication processes employed for ZONMs and discusses the advancements in synthesis techniques. Through an exploration of relevant studies, the review sheds light on the innovative approaches and methodologies utilized for the production of ZONMs across various research endeavours. Overall, this review provides valuable insights into the progressive advances and diversified applications of ZONMs, shedding light on their promising role in addressing various challenges in technology, healthcare, and environmental preservation.

Solid oxide fuel cells (SOFCs) are highly promising devices for efficient and low-emission energy conversion. The effective triple-phase boundary (TPB) density refers to the fraction of percolated TPB density that effectively contributes to the current production during cell operation. This is one of the most fundamental and least understood aspects of the cell design and performance assessment. This study methodically investigates the effective TPB density, using a computational fluid dynamics model based on the TPB-based kinetics and its correlation with the active anode thickness. Experimental data from previously published studies with varying thicknesses of anode functional layer and operating regimes are utilized to validate the model. The results of this study reaffirm that a significant fraction of the percolated TPB density in SOFCs remains unused during cell operation. This finding emphasizes the need to consider the effective TPB density for theoretical and experimental investigations focusing on optimizing cell performance. Furthermore, an inverse relationship is observed between the effective TPB density and the active anode thickness; a lower active anode thickness corresponds to a higher effective TPB density and vice versa. These findings contribute to advancing sustainable energy systems by guiding the development of more efficient SOFC designs and operational strategies that effectively utilize TPB sites. Graphical representation of the correlation between effective percolated triple-phase boundary density and active anode thickness. image

Complex oxides are an important class of materials with enormous potential for electrochemical applications. Depending on their composition and structure, such complex oxides can exhibit either a single conductivity (oxygen-ionic or protonic, or n-type, or p-type electronic) or a combination thereof generating distinct dual-conducting or even triple-conducting materials. These properties enable their use as diverse functional materials for solid oxide fuel cells, solid oxide electrolysis cells, permeable membranes and gas sensors. The literature review shows that the field of solid oxide materials and related electrochemical cells has a significant level of research engagement, with over 8,000 publications published since 2020. The manual analysis of such a large volume of material is challenging. However, by examining the review articles, it is possible to identify key patterns, recent achievements, prospects, and remaining obstacles. To perform such an analysis, the present article provides, for the first time, a comprehensive summary of previous review publications that have been published since 2020, with a special focus on solid oxide materials and electrochemical systems. Thus, this study provides an important reference for researchers specializing in the fields of solid state ionics, high-temperature electrochemistry, and energy conversion technologies.

Greenly synthesized nanoparticles have garnered attention due to their low environmental footprint, but impurities limit their applications. A novel semi-organic method for synthesizing silver nanoparticles (AgNPs) using bio-based chelating fuels (Beta vulgaris subsp., Spinacia oleracea, and Ipomoea batatas) reduces the undesirable impurities. The study also showcases the impact of bio-based chelating fuel on various characteristics of AgNPs in comparison to synthetic chelating fuel. The antimicrobial efficacy of the synthesized AgNPs in conjunction with honey was also assessed against E. coli. The XRD analysis showed cubic structure of AgNPs. The FESEM and TEM analysis showed that the well-connected spherical-shaped AgNPs (∼3–120 nm diameter) while EDS confirmed the presence of Ag in all samples. The TEM analysis also revealed layers of carbonates in AgNPs synthesized using bio-based chelating fuels. XPS investigation confirmed the absence of any prominent impurities in prepared samples and AgNPs have not experienced oxidation on their surface. However, notable surface charging effects due to the uneven conductivity of the particles were observed. The broth dilution method showed that all mixtures containing AgNPs in combination with honey exhibited a significant bacterial growth reduction over a period of 120 h. The highest growth reduction of ∼75% is obtained for the mixture having AgNPs (Ipomoea batatas) while the least growth reduction of ∼51% is obtained for the mixture having AgNPs (Beta vulgaris subsp.). The findings affirm that AgNPs can be successfully synthesized using bio-based chelating fuels with negligible ecological consequences and devoid of contaminants. Moreover, the synthesized AgNPs can be employed in conjunction with honey for antibacterial purposes.

Microbial fuel cell (MFC) technology is anticipated to be a practical alternative to the activated sludge technique for treating domestic and industrial effluents. The relevant literature mainly focuses on developing the systems and materials for maximum power output, whereas understanding the fundamental electrochemical characteristics is inadequate. This experimental study uses a double-chamber MFC having graphite electrodes and an anion-exchange membrane to investigate the electrochemical process limitations and the potential of bioelectricity generation and dairy effluent treatment. The results revealed an 81% reduction in the chemical oxygen demand (COD) in 10 days of cell operation, with an initial COD loading of 4520 mg/L. The third day recorded the highest open circuit voltage of 396 mV, and the maximum power density of 36.39 mW/m2 was achieved at a current density of 0.30 A/m2. The electrochemical impedance spectroscopy analysis disclosed that the activation polarization of the aerated cathode was the primary factor causing the cell’s resistance, followed by the ohmic and anodic activation overpotentials.

Ag-doped CeO2:BaO (ACBO) composite was synthesized by the simple solution combustion approach and investigated for its antibacterial and photocatalytic properties. CeO2 was doped with Ag 0.0-2.0 wt% as a part of the ACBO composite. Best antibacterial activity (ZOI = 13 mm) was measured against Bacillus by ACBO with 2.0 wt% Ag among the Pseudomonas, Bacillus, Staphylococcus and E. coli in comparison to Ciprofloxacin. Photocatalytic action against the methyl blue (598 nm) was also inspected, and a maximum degradation efficacy of 76% for the 2.0 wt% ACBO was observed in 16 min.