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Aqueous zinc-ion batteries (AZiBs) have emerged as a promising alternative to lithium-ion batteries as energy storage systems from renewable sources. Manganese hexacyanoferrate (MnHCF) is a Prussian Blue analogue that exhibits the ability to insert divalent ions such as Zn2+. However, in an aqueous environment, MnHCF presents weak structural stability and suffers from manganese dissolution. In this work, zinc doping is explored as a strategy to provide the structure with higher stability. Thus, through a simple and easy-to-implement approach, it has been possible to improve the stability and capacity retention of the cathode, although at the expense of reducing the specific capacity of the system. By correctly balancing the amount of zinc introduced into the MnHCF it is possible to reach a compromise in which the loss of capacity is not critical, while better cycling stability is obtained.

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Metal–organic frameworks and supramolecular metal–organic frameworks (SMOFs) exhibit great potential for a broad range of applications taking advantage of the high surface area and pore sizes and tunable chemistry. In particular, metalloporphyrin-based MOFs and SMOFs are becoming of great importance in many fields due to the bioessential functions of these macrocycles that are being mimicked. On the other hand, during the last years, proton-conducting materials have aroused much interest, and those presenting high conductivity values are potential candidates to play a key role in some solid-state electrochemical devices such as batteries and fuel cells. In this way, using metalloporphyrins as building units we have obtained a new crystalline material with formula [H(bipy)]2[(MnTPPS)(H2O)2]·2bipy·14H2O, where bipy is 4,4′-bipyidine and TPPS4− is the meso-tetra(4-sulfonatephenyl) porphyrin. The crystal structure shows a zig-zag water chain along the [100] direction located between the sulfonate groups of the porphyrin. Taking into account those structural features, the compound was tested for proton conduction by complex electrochemical impedance spectroscopy (EIS). The as-obtained conductivity is 1 × 10−2 S·cm−1 at 40 °C and 98% relative humidity, which is a remarkably high value.

Sodium batteries are receiving increasing interest as an alternative to reduce dependence on lithium-based systems. Furthermore, the development of solid-state electrolytes will lead to higher-performing and safer devices. In this work, a Zn-based metal–organic framework (Zn-MOF-74) is combined as a physical barrier against the growth of dendrites, together with 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIm][TFSI]) ionic liquid, which provides improved mobility to sodium ions. It is demonstrated that the incorporation of the appropriate amount of ionic liquid within the pores of the MOF produces a considerable increase in ionic conductivity, achieving values as high as 5 × 10−4 S cm−1 at room temperature, in addition to an acceptable Na+ transference number. Furthermore, the developed Na[EMIm][TFSI]@Zn-MOF-74 hybrid solid electrolyte contributes to stable and dendrite-free sodium plating/stripping for more than 100 h. Finally, a more than notable extension of the electrochemical stability window of the electrolyte has been determined, being useful even above 7 V vs. Na+/Na. Overall, this work presents a suitable strategy for the next generation of solid-state sodium batteries.

This review focuses on the combination of metal-organic frameworks (MOFs) and ionic liquids (ILs) to obtain composite materials to be used as solid electrolytes in metal-ion battery applications. Benefiting from the controllable chemical composition, tunable pore structure and surface functionality, MOFs offer great opportunities for synthesizing high-performance electrolytes. Moreover, the encapsulation of ILs into porous materials can provide environmentally benign solid-state electrolytes for electrochemical devices. Due to the versatility of MOF-based materials, in this review we also explore their use as anodes and cathodes in Li- and Na-ion batteries. Finally, solid IL@MOF electrolytes and their implementation into Li and Na batteries have been analyzed, as well as the design and advanced manufacturing of solid IL@MOF electrolytes embedded on polymeric matrices.

In recent years, much effort has been invested into developing multifunctional drug delivery systems to overcome the drawbacks of conventional carriers. Magnetic nanoparticles are not generally used as carriers but can be functionalised with several different biomolecules and their size can be tailored to present a hyperthermia response, allowing for the design of multifunctional systems which can be active in therapies. In this work, we have designed a drug carrier nanosystem based on Fe3O4 nanoparticles with large heating power and 4-amino-2-pentylselenoquinazoline as an attached drug that exhibits oxidative properties and high selectivity against a variety of cancer malignant cells. For this propose, two samples composed of homogeneous Fe3O4 nanoparticles (NPs) with different sizes, shapes, and magnetic properties have been synthesised and characterised. The surface modification of the prepared Fe3O4 nanoparticles has been developed using copolymers composed of poly(ethylene-alt-maleic anhydride), dodecylamine, polyethylene glycol and the drug 4-amino-2-pentylselenoquinazoline. The obtained nanosystems were properly characterised. Their in vitro efficacy in colon cancer cells and as magnetic hyperthermia inductors was analysed, thereby leaving the door open for their potential application as multimodal agents.

Hybrid supercapacitors, as emerging energy storage devices, have gained much attention in recent years due to their high energy density, fast charge/discharge and long cyclabilities. Among the wide range of systems covered by this topic, low cost, environmental friendliness and high power provide MnO2 with great characteristics to be a competitive candidate. The present work reports a hybrid aqueous supercapacitor system using a commercial activated carbon as the negative electrode and a synthesized manganese dioxide as the positive electrode. Two manganese dioxide polymorphs (α-MnO2 and δ-MnO2) were tested in different neutral and basic aqueous electrolytes. In this way, full cell systems that reached an energy density of 15.6 Wh kg−1 at a power density of 1 kW kg−1 were achieved. The electrode–electrolyte combination explored in this study exhibits excellent performance without losing capacity after 5000 charge/discharge cycles, leading to a promising approach towards more sustainable, high-performance energy storage systems.

Aprotic metal-O2 batteries have attracted the interest of the research community due to their high theoretical energy density that target them as potential energy storage systems for automotive applications. At present, these devices show various practical problems, which hinder the attainment of the high theoretical energy densities. Among the main limitations, we can highlight the irreversible parasitic reactions that lead to premature death of the battery. The degradation processes, mainly related to the electrolyte, lead to the formation of secondary products that accumulate throughout the cycling in the air electrode. This accumulation of predominantly insulating products results in the blocking of active sites, promoting less efficiency in system performance. Recently, it has been discovered that the superoxide intermediate radical anion is involved in the generation of the reactive oxygen singlet species (1O2) in metal-O2 batteries. The presence of singlet oxygen is intimately linked with electrolyte degradation processes and with carbon-electrode corrosion reactions. This review analyzes the nature of singlet oxygen, while clarifying its toxic role in metal-O2 batteries. Besides, the main mechanisms of deactivation of singlet oxygen are presented, trying to inspire the research community in the development of new molecules capable of mitigating the harmful effects related to this highly reactive species.

With the aim of studying the influence of synthesis parameters in structural and magnetic properties of cobalt-doped magnetite nanoparticles, Fe3−xCoxO4 (0 < x < 0.15) samples were synthetized by thermal decomposition method at different reaction times (30–120 min). The Co ferrite nanoparticles are monodisperse with diameters between 6 and 11 nm and morphologies depending on reaction times, varying from spheric, cuboctahedral, to cubic. Chemical analysis and X-ray diffraction were used to confirm the composition, high crystallinity, and pure-phase structure. The investigation of the magnetic properties, both magnetization and electronic magnetic resonance, has led the conditions to improve the magnetic response of doped nanoparticles. Magnetization values of 86 emu·g−1 at room temperature (R.T.) have been obtained for the sample with the highest Co content and the highest reflux time. Magnetic characterization also displays a dependence of the magnetic anisotropy constant with the varying cobalt content.

Cobalt-free perovskite oxides Pr1−xCaxFe0.8Ni0.2O3(PCFN) were investigated as novel cathodes for intermediate temperature solid oxide fuel cells (IT-SOFCs). Ca and Ni substitution in the PrFeO3material shows that a wide range of perovskites Pr1−xCaxFe0.8Ni0.2O3(0 < x< 0.9) can be prepared by sintering in air at 600 °C. Perovskites with 0 < x< 0.4 exhibit orthorhombic single phases (Pnmaspace group), whereas 0.4 < x< 0.9 show a coexistence of the perovskite and the brownmillerite-type structure (Ca2Fe2O5). The structure of the polycrystalline powders was analyzed by X-ray powder diffraction, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The analysis on the synthesized powders shows the presence of clusters formed by 30–100 nm nanoparticles. High-Resolution TEM (HRTEM) studies were carried out to confirm the existence of Ca2Fe2O5. The dc four-probe measurement exhibits a total electrical conductivity, over 100 S cm−1at T≥ 600 °C when 0 < x< 0.6, pointing out that strontium can be substituted for calcium without modifying the electrochemical properties. The Pr0.4Ca0.6Fe0.8Ni0.2O3/Ca2Fe2O5composite cathode presents the better performance in electrochemical measurements, showing an area specific resistance value of 0.09 ohm cm2at 850 °C. [ABSTRACT FROM AUTHOR]