Functional Materials Letters

A high performance and stable Li-ion conductive solid electrolyte is one of the key components for the future all-solid-state batteries with metallic lithium anodes. Phosphate, oxide and phosphosulfide-based inorganic solid electrolytes are currently under development. High ambient temperature Li-ion conductivities amounting up to 10${}^{-2}$ S cm${}^{-1}$ for the best performing electrolytes distinguish the phosphosulfides from the other material systems. Part I of the review starts with the motivation and background for the development of Li-phosphosulfide electrolytes followed by an overview of four different types of phosphosulfide electrolytes; the Li–P–S, thio-LiSICon, LGPS and the Argyrodite-type electrolytes. The core of part I is concerned with a detailed discussion of the phosphosulfide electrolyte types that have been under investigation already for a long time, the Li–P–S and the LiSICon. There is a multiplicity of different compositions within each of these types. The idea behind the outline of these sections is to point out the relations and differences between the different materials with respect to their chemistry related to the phase diagrams. Patterns for the relations among the materials identified in the phase diagrams are the base for a discussion of structure, processing and Li-ion conductivity within separate sections for each type and resulting in intra-type comparisons. The follow up part II will continue with a treatment of the more recently developed LGPS and Argyrodite-type electrolytes tracking the same concept, before addressing an inter-type comparison of ambient temperature Li-ion conductivities and the electrochemical stability of the electrolytes vs. metallic lithium. A final section in part II summarizes conclusions and provides perspectives for future research on Li-ion conductive phosphosulfide electrolytes.

A multi-footed composite hydrogel with double responsiveness was prepared by the combination of sodium alginate (SA), gelatin and ferroferric oxide nanomaterials. Under magnetic field control, the multi-footed composite hydrogel could walk and move to the designated locations and release some drugs under the specific environment (pH 7.4) due to the pH sensitivity of SA. The gelatin addition effectively improved the mechanical properties of composite hydrogel, adjusting the drug release behavior of composite hydrogel by the decreased porous structure. Our results demonstrated that the proposed dual stimulus-responsive composite hydrogel could offer a promising choice for medical fixed-point drug release and disease treatment.

NiO/Pt nanotubes were obtained by firstly preparing the NiO nanotube with self-sacrificial templating methods and subsequently loading Pt nanoparticles with microwave assistant procedures. The as-prepared NiO/Pt nanotubes sensors displayed better electrocatalytic activities for glucose oxidation. The detection limit and sensitivity for glucose detection are 0.3 $\mu$M and 418.28 $\mu$A⋅ mM${}^{-1}$⋅cm${}^{-2}$ in the range of 1 $\mu$M-4000 $\mu$M. In addition, the practicality of NiO/Pt nanotubes was also confirmed by determining the glucose in serum specimen.

Carbon nanotubes (CNTs) were proposed to improve the electrochemical performances of copper fluoride (CuF${}_2)$ via a coprecipitation method. FE-SEM and TEM results proved that the three-dimensional conductive network was constructed by the addition of CNTs in the composites, in which some CuF₂ particles attached to the outside of CNTs, and some of them grew inside the tube. According to the charge–discharge tests, with CNTs content increasing from 0 wt.% to 30 wt.%, the initial discharge capacities of CuF₂ increased from 461 to 571 mAh/g, which exceeded the theoretical specific capacity of the CuF₂. Moreover, the electrodes with CNTs exhibited better reversibility and rate performance than the bare electrode. CV and EIS results confirmed that the enhancements could be attributed to the inhibition of the electrochemical polarization of the electrode and the improvement on the diffusion coefficient of lithium ion in the electrode by the addition of CNTs.

Photocatalytic decomposition of water is a potential way to obtain hydrogen directly from solar energy. Of all the potential semiconductors, Bi₂S₃has attracted much attention due to its high utilization of sunlight. In this paper, Bi₂S₃nanowires with different morphologies and crystallinities were synthesized by a modified composite molten salt (M-CMS) method over different reaction times. Through the systematic characterization of the samples, it was found that Bi₂S₃samples with a longer synthesis times tend to form nanowires with a uniform morphology, clean surface, good crystallinity and lower photogenerated carrier recombination rate, and they can achieve efficient utilization of solar energy and high catalytic hydrogen production efficiency. The Bi₂S₃nanowires synthesized over 72 h had the best hydrogen production of 392 $\mu$mol/g within 2 h, and they still maintained an efficiency of 89% after four cycles.

Currently, nanowires present a type of unique one-dimensional materials showing promising prospects in many fields. The octahedron molecular sieve (OMS-2, with chemical compositions of K${}_{2-}$${}_x$Mn₈O₁₆) materials are utilized extensively as efficient catalysts for numerous critical reactions. In this work, it was found that the evolution from $\gamma$-MnOOH microrod to OMS-2 nanowire can be induced facilely by altering the temperature of hydrothermal treatment. The obtained OMS-2 nanowire exhibited high catalytic activity and high durability in peroxymonosulfate (PMS) activated degradation of rhodamine B (RhB) or methylene blue (MB). Under optimum conditions (OMS-2 catalyst: 0.1 g⋅L${}^{-1}$; RhB or MB: 8 mg⋅L${}^{-1}$, 100 mL), the degradation can be completed within 10 min. The possible reason for OMS-2 nanowire’s high performance was also proposed.

Rechargeable aqueous zinc-ion battery (RAZIB) shows great practical value as energy storage system owing to the high safety, low cost, non-polluting, high energy and high power density. However, it still faces a series of scientific and technical problems, such as the undesirable cycling stability and high-rate capability. Herein, we synthesized micro-sized MnCO₃ cubes as a novel cathode for aqueous zinc-ion battery, where the cathode materials has the phase transition from rhodochrosite MnCO₃ to layered-type ZnMnO₃ induced by the continuous uptake/removal of zinc ions during electrochemical cycling. The RAZIB has a specific capacity of 97.6 mA h g${}^{-1}$and distinguished cycling stability up to 5000 cycles with 79.1% retention at 1.8 A g${}^{-1}$. This work benefits for the electrochemical performance of aqueous zinc-ion battery, and clarifies the understanding of its electrochemical mechanism.

Local electronic structure of carbon nanotubes (CNTs) consolidated by spark plasma sintering and further oxidized by nitric acid was studied by electron paramagnetic resonance (EPR), transmission electron microscopy, X-ray photoelectron and Raman spectroscopy. It was found that long time oxidation perforated and fragmented sintered CNTs and increased the oxygen content in the material causing an increase in the number of paramagnetic centers. Two components in the absorption EPR spectra were distinguished: A narrow and a broad line with different $g$-factors, which testifies the different surrounding of paramagnetic centers associated with the lines. The results are of great importance for understanding the mechanism of nanotubes oxidation and development new types of catalysts, electromagnetic shielding materials and absorbents.

Thin TiO₂-films were synthesized for the first time by solid-phase low-temperature pyrolysis technique onto quartz glasses or silicon substrates. The obtained films are nanoscale; crystallize in a mixed anatase-rutile modification, which was confirmed by X-ray diffraction, scanning electron and atomic force microscopy (AFM) methods. The three-layer films’ thickness was 140 nm. The TiO₂-films consist of crystallites 12–27 nm, depending on the temperature treatment and phase composition. In addition, all of the obtained TiO₂-films are optically transparent regardless of synthesis conditions; the calculated band gap was 3.55 eV, which makes it possible to recommend TiO₂-films for use in optical filters and gas sensors.

Monoclinic Mn₅O₈, spinel Mn₃O₄, and perovskite Mn ₂O₃were prepared by thermal decomposition of MnC₂O₄. The formation of different MnOx species observed by thermogravimetric analysis (TGA) and X-ray diffraction (XRD) measurements showed temperature-dependent phase transformation following the path of MnC₂O ₄$\to$Mn₅O₈$\to$Mn₃O₄$\to$Mn₂O ₃occurring during the heat treatment process. Among these manganese oxides, the MO-1 (Mn₅O₈ ) showed the best light-driven photothermal catalytic performance reaching up to 99% of toluene degradation and 75% of mineralization efficiencies reached within 30 min. Besides, it is found that structural defects decrease with the increase of the calcinated temperature, and the Mn${}^{4+}$/Mn${}^{3+}$active sites and oxygen vacancies play an important role in improving the light-driven photothermal catalytic performance.