Structural Evolution of Manganese Prussian Blue Analogue in Aqueous ZnSO4 Electrolyte.

Among different Prussian Blue Analogues (PBAs), manganese hexacyanoferrate (MnHCF), with open framework and two abundant electroactive metal sites, exhibits high potential for the grid-scale aqueous rechargeable zinc-ion batteries (ARZIBs) application. Until now, the intercalation mechanism of Zn2+ into MnHCF has not been clearly illustrated. In this work, combining different synchrotron X-ray techniques, the structural and microscopic evolution of MnHCF in 3 m ZnSO4 electrolyte is comprehensively studied, and a thorough understanding of the intercalation/release dynamic, in terms of local and long-range domain, is provided. The elemental distribution and structural information of Fe, Mn, Zn inside MnHCF electrodes is obtained from the X-ray fluorescence (XRF) elemental maps and X-ray absorption spectroscopy (XAS). The in-depth analysis of extended X-ray absorption fine structure (EXAFS) signals confirm that the rearrangement of Mn site, evidencing the cleavage of the Mn─N bond with the formation of a Mn─O bond, in an octahedral environment. The phase transformation of MnHCF takes place exclusively during the 1st cycle, and a mixture of rhombohedral and cubic zinc hexacynoferrate (ZnHCF) phases are formed during the first charge process. Thereafter, the newly formed cubic ZnHCF phase becomes the only stable one, existing in the subsequent cycles and exhibiting excellent electrochemical stability.

Operando Studies of Bismuth Nanoparticles Embedded in N, O-Doped Porous Carbon for High-Performance Potassium-Ion Hybrid Capacitor.

A highly viable alternative to lithium-ion batteries for stationary electrochemical energy-storage systems is the potassium dual-ion hybrid capacitor (PIHC), especially toward fast-charging capability. However, the sluggish reaction kinetics of negative electrode materials seriously impedes their practical implementation. In this paper, a new negative electrode Bi@RPC (Nano-bismuth confined in nitrogen- and oxygen-doped carbon with rationally designed pores, evidenced by advanced characterization) is developed, leading to a remarkable electrochemical performance. PIHCs building with the active carbon YP50F positive electrode result in a high operation voltage (0.1-4 V), and remarkably well-retained energy density at a high-power density (11107 W kg-1 at 98 Wh kg-1). After 5000 cycles the proposed PHICs still show a superior capacity retention of 92.6%. Moreover, a reversible mechanism of "absorption-alloying" of the Bi@RPC nanocomposite is revealed by operando synchrotron X-ray diffraction and Raman spectroscopy. With the synergistic potassium ions storage mechanism arising from the presence of well-structured pores and nano-sized bismuth, the Bi@RPC electrode exhibits an astonishingly rapid kinetics and high energy density. The results demonstrate that PIHCs with Bi@RPC-based negative electrode is the promising option for simultaneously high-capacity and fast-charging energy storage devices.

Atomic Structure Amorphization and Electronic Structure Reconstruction of FeCoNiCrMox High-Entropy Alloy Nanoparticles for Highly Efficient Water Oxidation.

The complexity of the multielement interaction in high-entropy alloys (HEAs) may provide more active sites to adapt different catalytic reaction steps in oxygen evolution reaction (OER). Investigating the correlation between structure and performance of HEAs electrocatalysts is both essential and challenging. In this work, FeCoNiCrMox HEA nanoparticles are successfully fabricated utilizing a unique nanofabrication method called inert gas condensation. With the increase of high-valence metal component Mo, the atomic structure amorphization and electronic structure reconstruction are unveiled. According to the X-ray photoelectron spectroscopy valence spectra, the d-band center of FeCoNiCrMox is ascending, and thus enhancing the adsorption energy. Synchrotron pair distribution function analysis reflects the degree of structural disorder and reveals a robust correlation with the intrinsic OER activities of the electrocatalysts. FeCoNiCrMo1.0 high-entropy metallic glass nanoparticles exhibit an outstanding OER performance with an ultralow overpotential of 294.5 mV at a high current density of 100 mA cm-2. This work brings fundamental and practical insights into the modulation mechanism of metal components of HEAs catalysts for developing OER.

Synthesis of Free-Standing Pd-Ni-P Metallic Glass Nanoparticles with Durable Medium-Range Ordered Structure for Enhanced Electrocatalytic Properties.

Topologically disordered metallic glass nanoparticles (MGNPs) with highly active and tailorable surface chemistries have immense potential for functional uses. The synthesis of free-standing MGNPs is crucial and intensively pursued because their activity strongly depends on their exposed surfaces. Herein, a novel laser-evaporated inert-gas condensation method is designed and successfully developed for synthesizing free-standing MGNPs without substrates or capping agents, which is implemented via pulse laser-induced atomic vapor deposition under an inert helium atmosphere. In this way, the metallic atoms vaporized from the targets collide with helium atoms and then condense into short-range-order (SRO) clusters, which mutually assemble to form the MGNPs. Using this method, free-standing Pd40 Ni40 P20 MGNPs with a spherical morphology are synthesized, which demonstrates satisfactory electrocatalytic activity and durability in oxygen reduction reactions. Moreover, local structure investigations using synchrotron pair distribution function techniques reveal the transformation of SRO cluster connection motifs of the MGNPs from face-sharing to edge-sharing modes during cyclic voltammetry cycles, which enhances the electrochemical stability by blocking crystallization. This approach provides a general strategy for preparing free-standing MGNPs with high surface activities, which may have widespread functional applications.

Editorial for focus on nanophase materials for next-generation lithium-ion batteries and beyond.

Lithium-ion batteries (LIBs) have revolutionized our society in many respects, and we are expecting even more favorable changes in our lifestyles with newer battery technologies. In pursuing such eligible batteries, nanophase materials play some important roles in LIBs and beyond technologies. Stimulated by their beneficial effects of nanophase materials, we initiated this Focus. Excitingly, this Focus collects 13 excellent original research and review articles related to the applications of nanophase materials in various rechargeable batteries, ranging from nanostructured electrode materials, nanoscale interface tailoring, novel separators, computational calculations, and advanced characterizations.

Highly Reversible Sodiation/Desodiation from a Carbon-Sandwiched SnS2 Nanosheet Anode for Sodium Ion Batteries.

The further improvement of sodium ion batteries requires the elucidation of the mechanisms pertaining to reversibility, which allows the novel design of the electrode structure. Here, through a hydrogel-embedding method, we are able to confine the growth of few-layer SnS2 nanosheets between a nitrogen- and sulfur-doped carbon nanotube (NS-CNT) and amorphous carbon. The obtained carbon-sandwiched SnS2 nanosheets demonstrate excellent sodium storage properties. In operando small-angle X-ray scattering combined with the ex situ X-ray absorption near edge spectra reveal that the redox reactions between SnS2/NS-CNT and the sodium ion are highly reversible. On the contrary, the nanostructure evolution is found to be irreversible, in which the SnS2 nanosheets collapse, followed by the regeneration of SnS2 nanoparticles. This work provides operando insights into the chemical environment evolution and structure change of SnS2-based anodes, elucidating its reversible reaction mechanism, and illustrates the significance of engineered carbon support in ensuring the electrode structure stability.

Zinc incorporation in marine bivalve shells grown in mine-polluted seabed sediments: a case study in the Malfidano mining area (SW Sardinia, Italy).

Zinc incorporation into marine bivalve shells belonging to different genera (Donax, Glycymeris, Lentidium, and Chamelea) grown in mine-polluted seabed sediments (Zn up to 1% w/w) was investigated using x-ray diffraction (XRD), chemical analysis, soft x-ray microscopy combined with low-energy x-ray fluorescence (XRF) mapping, x-ray absorption spectroscopy (XAS), and transmission electron microscopy (TEM). These bivalves grew their shells, producing aragonite as the main biomineral and they were able to incorporate up to 2.0-80 mg/kg of Zn, 5.4-60 mg/kg of Fe and 0.5-4.5 mg/kg of Mn. X-ray absorption near edge structure (XANES) analysis revealed that for all the investigated genera, Zn occurred as independent Zn mineral phases, i.e., it was not incorporated or adsorbed into the aragonitic lattice. Overall, our results indicated that Zn coordination environment depends on the amount of incorporated Zn. Zn phosphate was the most abundant species in Donax and Lentidium genera, whereas, Chamelea shells, characterized by the highest Zn concentrations, showed the prevalence of Zn-cysteine species (up to 56% of total speciation). Other Zn coordination species found in the investigated samples were Zn hydrate carbonate (hydrozincite) and Zn phosphate. On the basis of the coordination environments, it was deduced that bivalves have developed different biogeochemical mechanisms to regulate Zn content and its chemical speciation and that cysteine plays an important role as an active part of detoxification mechanism. This work represents a step forward for understanding bivalve biomineralization and its significance for environmental monitoring and paleoreconstruction.

Perspective on Structural Evolution and Relations with Thermophysical Properties of Metallic Liquids.

The relationship between the structural evolution and properties of metallic liquids is a long-standing hot issue in condensed-matter physics and materials science. Here, recent progress is reviewed in several fundamental aspects of metallic liquids, including the methods to study their atomic structures, liquid-liquid transition, physical properties, fragility, and their correlations with local structures, together with potential applications of liquid metals at room temperature. Involved with more experimentally and theoretically advanced techniques, these studies provide more in-depth understanding of the structure-property relationship of metallic liquids and promote the design of new metallic materials with superior properties.