Structural complexity in Prussian blue analogues

Inhibiting the Jahn-Teller Effect of Manganese Hexacyanoferrate via Ni and Cu Codoping for Advanced Sodium-Ion Batteries

Manganese (Mn)-based Prussian blue analogs (PBAs) are of great interest as a prospective cathode material for sodium-ion batteries (SIBs) due to their high redox potential, easy synthesis, and low cost. However, the Jahn-Teller effect and low electrical conductivity of Mn-based PBA cause poor structure stability and unsatisfactory performance during the cycling. Herein, a novel nickel- and copper-codoped K2Mn[Fe(CN)6] cathode is developed via a simple coprecipitation strategy. The doping elements improve the electrical conductivity of Mn-based PBA by reducing the bandgap, as well as suppress the Jahn-Teller effect by stabilizing the framework, as verified by the density functional theory calculations. Simultaneously, the substitution of sodium with potassium in the lattice is beneficial for filling vacancies in the PBA framework, leading to higher average operating voltages and superior structural stability. As a result, the as-prepared Mn-based cathode exhibits excellent reversible capacity (116.0 mAh g-1 at 0.01 A g-1) and superior cycling stability (81.8% capacity retention over 500 cycles at 0.1 A g-1). This work provides a profitable doping strategy to inhibit the Jahn-Teller structural deformation for designing stable cathode material of SIBs.

Exploring affinity between organic probes and Prussian Blue Analogues via inverse gas chromatography

Prussian Blue Analogues (PBAs), which are characterized by their open structure, high stability, and non-toxic properties, have recently been the subject of research for various applications, including their use as electrode precursors for capacitive deionization, gas storage, and environmental purification. These materials can be readily tailored to enhance their affinity towards gases for integration with sensing devices. An improved understanding of PBA-gas interactions is expected to enhance material development and existing sensor deposition schemes greatly. The use of inverse gas chromatography (IGC) is a robust approach for examining the relationship between porous materials and gases. In this study, the adsorption properties of (functionalized) hydrocarbons, i.e., probe molecules, on the copper hexacyanoferrate (CuHCF) lattice were studied via IGC, demonstrating that alkylbenzenes have a higher affinity for this material than n-alkanes. This difference was rationalized by steric hindrance, π-π interactions, and vapour pressure effects. Along the same line, the five isomers of hexane showed decreasing selectivity upon increased steric hindrance. Enthalpy values for n-pentane, n-hexane and n-heptane were lower than that of toluene. The introduction of increased probe masses resulted in a surface coverage of 46% for toluene. For all n-alkane probe molecules this percentage was lower. However, the isotherms of these probes did not show saturation points and the observed linear regime proves beneficial for gas sensing. Our work demonstrates the versatility of CuHCF for gas sensing purposes and the potential of IGC to characterize the adsorption characteristics of such a porous nanomaterial.

Local Structure and Dynamics in MPt(CN)6 Prussian Blue Analogues

We use a combination of X-ray pair distribution function (PDF) measurements, lattice dynamical calculations, and ab initio density functional theory (DFT) calculations to study the local structure and dynamics in various MPt(CN)6 Prussian blue analogues. In order to link directly the local distortions captured by the PDF with the lattice dynamics of this family, we develop and apply a new "interaction-space" PDF refinement approach. This approach yields effective harmonic force constants, from which the (experiment-derived) low-energy phonon dispersion relations can be approximated. Calculation of the corresponding Grüneisen parameters allows us to identify the key modes responsible for negative thermal expansion (NTE) as arising from correlated tilts of coordination octahedra. We compare our results against the phonon dispersion relations determined using DFT calculations, which identify the same NTE mechanism.

Toward Ultrahigh Rate and Cycling Performance of Cathode Materials of Sodium Ion Battery by Introducing a Bicontinuous Porous Structure

The emerging sodium-ion batteries (SIBs) are one of the most promising candidates expected to complement lithium-ion batteries and diversify the battery market. However, the exploitation of cathode materials with high-rate performance and long-cycle stability for SIBs has remained one of the major challenges. To this end, an efficient approach to enhance rate and cycling performance by introducing an ordered bicontinuous porous structure into cathode materials of SIBs is demonstrated. Prussian blue analogues (PBAs) are selected because they are recognized as a type of most promising SIB cathode materials. Thanks to the presence of 3D continuous channels enabling fast Na+ ions diffusion as well as the intrinsic mechanical stability of bicontinuous architecture, the resultant PBAs exhibit excellent rate capability (80 mAh g-1 at 2.5 A g-1) and ultralong cycling life (>3000 circulations at 0.5 A g-1), reaching the top performance of the reported PBA-based cathode materials. This study opens a new avenue for boosting sluggish ion diffusion kinetics in electrodes of rechargeable batteries and also provides a new paradigm for solving the dilemma that electrodes' failure due to high-stress concentration upon ion storage.

Construction of CoNi2S4/Co9S8@Co4S3 nanocubes derived from Ni-Co prussian blue analogues@cobalt carbonate hydroxide core-shell heterostructure for asymmetric supercapacitor

Construction of Prussian blue analogues (PBAs) with heterostructure is beneficial to preparing PBAs derivatives with superior electrochemical performance. In this work, the core-shell nanostructured nanocubes composed of nickel hexacyanocobalt PBA (NiCo-PBA)@cobalt carbonate hydroxide (CCH) are synthesized through an in-situ epitaxial growth strategy, and the formation mechanisms of coating are carefully validated and specifically discussed. Then, the precursors are successfully transformed into hierarchical CoNi2S4/Co9S8@Co4S3 via the gas-phase vulcanization method. Benefiting from the intriguing heterostructure and multicomponent sulfides, the CoNi2S4/Co9S8@Co4S3-80 electrode exhibits a high specific capacity of 799 ± 16C/g (specific capacitance of 1595 ± 31F/g) at 1 A/g, ultra-high capacity retention of 80 % at a high current density of 20 A/g. The assembled asymmetric supercapacitor (ASC) device delivers a high energy density of 43.3 Wh kg-1 at a power density of 899 W kg-1 and exhibits superior cycling stability with the capacity retention of 88 % after 5,000 cycles. Subsequently, the fabricated all-solid-state ASC device shows an excellent energy density of 36.4 Wh kg-1 with a power density of 824 W kg-1. This work proposing rational design of combining multicomponent sulfides and core-shell heterostructure based on PBA nanocubes opens up a novel route for developing asymmetric supercapacitor electrode materials with superior performance.

Interior-Confined Vacancy in Potassium Manganese Hexacyanoferrate for Ultra-Stable Potassium-Ion Batteries

Metal hexacyanoferrates (HCFs) are viewed as promising cathode materials for potassium-ion batteries (PIBs) because of their high theoretical capacities and redox potentials. However, the development of an HCF cathode with high cycling stability and voltage retention is still impeded by the unavoidable Fe(CN)6 vacancies (VFeCN) and H2O in the materials. Here, a repair method is proposed that significantly reduces the VFeCN content in potassium manganese hexacyanoferrate (KMHCF) enabled by the reducibility of sodium citrate and removal of ligand H2O at high temperature (KMHCF-H). The KMHCF-H obtained at 90 °C contains only 2% VFeCN, and the VFeCN is concentrated in the lattice interior. Such an integrated Fe-CN-Mn surface structure of the KMHCF-H cathode with repaired surface VFeCN allows preferential decomposition of potassium bis(fluorosulfonyl)imide (KFSI) in the electrolyte, which constitutes a dense anion-dominated cathode electrolyte interphase (CEI) , inhibiting effectively Mn dissolution into the electrolyte. Consequently, the KMHCF-H cathode exhibits excellent cycling performance for both half-cell (95.2 % at 0.2 Ag-1 after 2000 cycles) and full-cell (99.4 % at 0.1 Ag-1 after 200 cycles). This thermal repair method enables scalable preparation of KMHCF with a low content of vacancies, holding substantial promise for practical applications of PIBs.

Defect-Free Prussian Blue Analogue as Zero-Strain Cathode Material for High-Energy-Density Potassium-Ion Batteries

Prussian blue analogues (PBAs) have been widely studied as cathodes for potassium-ion batteries (PIBs) due to their three-dimensional framework structure and easily adjustable composition. However, the phase transition behavior and [Fe(CN)6]4- anionic defects severely deteriorate electrochemical performances. Herein, we propose a defect-free potassium iron manganese hexacyanoferrate (K1.47Fe0.5Mn0.5[Fe(CN)6]·1.26H2O, KFMHCF-1/2) as the cathode material for PIBs. The Fe-Mn binary synergistic and defect-free effects can inhibit the cell volume change and octahedral slip during the K-ion insertion/extraction process, so that the phase transformation behavior (monoclinic ↔ cubic) is effectively inhibited, achieving a zero-strain solid solution mechanism employing Fe and Mn as dual active-sites. Thus, KFMHCF-1/2 contributes the highest initial capacity of 155.3 mAh·g-1 with an energy density of 599.5 Wh·kg-1 at 10 mA·g-1 among the reported PBA cathodes, superior rate capability, and cyclic stability over 450 cycles. The assembled K-ion full battery using K deposited on graphite (K@G) as anode also delivers high reversible specific capacity of 131.1 mAh·g-1 at 20 mA·g-1 and ultralong lifespans over 1000 cycles at 50 mA·g-1 with the lowest capacity decay rate of 0.044% per cycle. This work will promote the rapid application of high-energy-density PIBs.

Nanosized Prussian blue and its analogs for bioimaging and cancer theranostics

Prussian blue (PB) nanoparticles (NPs) and Prussian blue analogs (PBAs) can form metal-organic frameworks through the programmable coordination of ferrous ions with cyanide. PB and PBAs represent a burgeoning class of hybrid functional nano-systems with a wide-ranging application spectrum encompassing biomedicine, cancer diagnosis, and therapy. A comprehensive overview of recent advancements is crucial for gaining insights for future research. In this context, we reviewed the synthesis techniques and surface modification strategies employed to tailor the dimensions, morphology, and attributes of PB NPs. Subsequently, we explored advanced biomedical utilities of PB NPs, encompassing photoacoustic imaging, magnetic resonance imaging, ultrasound (US) imaging, and multimodal imaging. In particular, the application of PB NPs-mediated photothermal therapy, photodynamic therapy, and chemodynamic therapy to cancer treatment was reviewed. Based on the literature, we envision an evolving trajectory wherein the future of Prussian blue-driven biological applications converge into an integrated theranostic platform, seamlessly amalgamating bioimaging and cancer therapy. STATEMENT OF SIGNIFICANCE: Prussian blue, an FDA-approved coordinative pigment with a centuries-long legacy, has paved the way for Prussian blue nanoparticles (PB NPs), renowned for their remarkable biocompatibility and biosafety. These PB NPs have found their niche in biomedicine, playing crucial roles in both diagnostics and therapeutic applications. The comprehensive review goes beyond PB NP-based cancer therapy. Alongside in-depth coverage of PB NP synthesis and surface modifications, the review delves into their cutting-edge applications in the realm of biomedical imaging, encompassing techniques such as photoacoustic imaging, magnetic resonance imaging, ultrasound imaging, and multimodal imaging.

Progress on Transition Metal Ions Dissolution Suppression Strategies in Prussian Blue Analogs for Aqueous Sodium-/Potassium-Ion Batteries

Aqueous sodium-ion batteries (ASIBs) and aqueous potassium-ion batteries (APIBs) present significant potential for large-scale energy storage due to their cost-effectiveness, safety, and environmental compatibility. Nonetheless, the intricate energy storage mechanisms in aqueous electrolytes place stringent requirements on the host materials. Prussian blue analogs (PBAs), with their open three-dimensional framework and facile synthesis, stand out as leading candidates for aqueous energy storage. However, PBAs possess a swift capacity fade and limited cycle longevity, for their structural integrity is compromised by the pronounced dissolution of transition metal (TM) ions in the aqueous milieu. This manuscript provides an exhaustive review of the recent advancements concerning PBAs in ASIBs and APIBs. The dissolution mechanisms of TM ions in PBAs, informed by their structural attributes and redox processes, are thoroughly examined. Moreover, this study delves into innovative design tactics to alleviate the dissolution issue of TM ions. In conclusion, the paper consolidates various strategies for suppressing the dissolution of TM ions in PBAs and posits avenues for prospective exploration of high-safety aqueous sodium-/potassium-ion batteries.

Spectroscopic Characterization of Mn1+ Low Oxidation State in Prussian Blue-Based Battery Anodes

Stabilization of ions in exotic oxidation states is beneficial for the development of new materials for green energy technologies. Exotic Mn1+ was proposed to play a role in the function of sodium-based Prussian blue analogues (PBA) batteries, a highly sought-out technology for industrial energy storage. Here, we report the detailed electronic structure characterization of uncharged and charged sodium-based manganese hexacyanomanganate anodes via Mn K-edge X-ray absorption spectroscopy (XAS), Kβ nonresonant X-ray emission (XES), and resonant inelastic X-ray scattering (RIXS). The latter allowed us to obtain site-selective XANES information about two distinct Mn centers. The obtained spectroscopic data represent the first electronic structure characterization of low-spin Mn1+ using hard X-ray RIXS and XES and allowed us to confirm its role in anode reduction. Our experimental approach can be expanded to analysis of analogues with other 3d transition metals broadening the application of exotic ionic states in materials engineering.

Advances of Zn Metal-Free "Rocking-Chair"-Type Zinc Ion Batteries: Recent Developments and Future Perspectives

Aqueous zinc ion battery (AZIBs) has attracted the attention of many researchers because of its safety, economy, environmental protection, and high ionic conductivity of electrolytes. However, the battery greatly suffers from zinc dendrite produced by zinc metal anode leading to poor cycle life and even unsafe problems, which limit its further development for various important applications. It is known that the success of the commercialization of lithium-ion batteries (LIBs) is mainly due to replacement of lithium metal anode with graphite, which avoids the formation of Li dendrite. Therefore, it is an important step to develop aqueous zinc ion anode to replace conventional zinc metal one with zinc-metal free anode material. In this review, the working principle and development prospect of "rocking-chair" AZIBs are introduced. The research progress of different types of zinc metal-free anode materials and cathode materials in "rocking-chair" AZIBs is reviewed. Finally, the limitations and challenges of the Zn metal-free "rocking-chair" AZIBs as well as solutions are deeply discussed, aiming to provide new strategies for the development of advanced zinc-ion batteries.

Effect of the Interaction between Transition Metal Redox Center and Cyanide Ligand on Structural Evolution in Prussian White Cathodes

Transition metal (TM) based Prussian whites, comprising a cyanide anion ((C≡N)-) and TM cations in an alternative manner, have been widely adopted as cathode materials for rechargeable batteries. Prussian whites are characterized by the TM electronic states that exclusively adopt low spin (LS) toward the C atom and high spin (HS) toward the N atom through the hybridized covalent bonding in the TM─C≡N─TM unit with the average oxidation states of the TM ions being 2+, considerably affecting the phase transition behavior upon the release and storage of carrier ions; however, there have been only a few studies on their associated features. Herein, Prussian whites with different HS TM ions were synthesized via coprecipitation and the phase transition behavior controlled by the π electron interaction between the cyanide anions and TM ions during battery operations was investigated. In situ X-ray characterizations reveal that the combined effect of π backdonation in the LS Fe-C unit and π donation in the HS TM-N unit effectively controls the bond length of the TM─C≡N─TM building unit, thus markedly influencing the lattice volume of a series of Prussian white cathodes during the charge/discharge process. This study presents a comprehensive understanding of the structure-property relationship of the Prussian white cathodes involving π electron interactions during battery operations.

The uniaxial zero thermal expansion and zero linear compressibility in distorted Prussian blue analogue RbCuCo(CN)6

The uniaxial zero thermal expansion (ZTE) in distorted Prussian blue analogue (PBA) RbCuCo(CN)6 is reproduced by employing first-principles calculations, which agrees well with the experimental data. Also, the zero linear compressibility (ZLC) behavior in RbCuCo(CN)6 can be found. The special Jahn-Teller distortion introduced by Cu2+ in RbCuCo(CN)6 is noticed by investigating the change of the local structure with temperature and hydrostatic pressure. The lattice thermal conductivity (LTC) and phonon group velocity of RbCuCo(CN)6 are studied, where the LTC and phonon group velocity are significantly anisotropic. Especially, RbCuCo(CN)6 exhibits a quite low LTC, and its c-axis shows a characteristic of glasslike LTC at low temperatures. Our work facilitates a deep understanding of the coexistence mechanisms of uniaxial ZTE and ZLC properties in RbCuCo(CN)6.

K-Ion Slides in Prussian Blue Analogues

We study the phenomenology of cooperative off-centering of K+ ions in potassiated Prussian blue analogues (PBAs). The principal distortion mechanism by which this off-centering occurs is termed a "K-ion slide", and its origin is shown to lie in the interaction between local electrostatic dipoles that couple through a combination of electrostatics and elastic strain. Using synchrotron powder X-ray diffraction measurements, we determine the crystal structures of a range of low-vacancy K2M[Fe(CN)6] PBAs (M = Ni, Co, Fe, Mn, Cd) and establish an empirical link between composition, temperature, and slide-distortion magnitude. Our results reflect the common underlying physics responsible for K-ion slides and their evolution with temperature and composition. Monte Carlo simulations driven by a simple model of dipolar interactions and strain coupling reproduce the general features of the experimental phase behavior. We discuss the implications of our study for optimizing the performance of PBA K-ion battery cathode materials and also its relevance to distortions in other, conceptually related, hybrid perovskites.

Predicting Distortion Magnitudes in Prussian Blue Analogues

Based on simple electrostatic and harmonic potential considerations, we derive a straightforward expression linking the composition of a Prussian blue analogue (PBA) to its propensity to undergo collective structural distortions. We demonstrate the existence of a threshold value, below which PBAs are undistorted and above which PBAs distort by a degree that is controlled by a geometric tolerance factor. Our analysis rationalizes the presence, absence, and magnitude of distortions in a wide range of PBAs and distinguishes their structural chemistry from that of other hybrid perovskites.

Defect-Healing Induced Monoclinic Iron-Based Prussian Blue Analogs as High-Performance Cathode Materials for Sodium-Ion Batteries

Prussian blue analogs (PBAs) have attracted wide interest as a class of ideal cathodes for rechargeable sodium-ion batteries due to their low cost, high theoretical capacity, and facile synthesis. Herein, a series of highly crystalline Fe-based PBAs (FeHCF) cubes, where HCF stands for the hexacyanoferrate, is synthesized via a one-step pyrophosphate-assisted co-precipitation method. By applying this proposed facile crystallization-controlled method to slow down the crystallization process and suppress the defect content of the crystal framework of the PBAs, the as-prepared materials demonstrate high crystallization and a sodium-rich induced rhombohedral phase. As a result, the as prepared FeHCF can deliver a high specific capacity of up to 152.0 mA h g-1 (achieving ≈90% of its theoretical value) and an excellent rate capability with a high-capacity retention ratio of 88% at 10 C, which makes it one of the most competitive candidates among the cathodes reported regarding both capacity and rate performance. A highly reversible three-phase-transition sodium-ion storage mechanism has been revealed via multiple in situ techniques. Furthermore, the full cells fabricated with as-prepared cathode and commercial hard carbon anode exhibit excellent compatibility which shows great prospects for application in the large-scale energy storage systems.

Manganese-enriched photonic/catalytic nanomedicine augments synergistic anti-TNBC photothermal/nanocatalytic/immuno-therapy via activating cGAS-STING pathway

As the clinical efficacy of immunotherapy for triple-negative breast cancer (TNBC) remains limited, exploring new immunotherapy approaches is still indispensable. Mn²⁺ has been proven as a cGAS-STING agonist to remarkably enhance antitumor immunity. Here, we report a combined tumor-therapeutic strategy based on Prussian blue (PB)-mediated photothermal therapy with Mn²⁺-augmented immunotherapy by synergistically activating the cGAS-STING pathway. Mn-enriched photonic nanomedicine (MnPB-MnO_x) were constructed by integrating MnO_x onto the surface of Mn-doped PB nanoparticles. All components of MnPB-MnO_x are biocompatible and biodegradable, wherein sufficient Mn are endowed through rational nanostructure design, conferring easier cGAS-STING activation. Additionally, tumor hyperthermia strengthened by MnPB under near-infrared light radiation, synergistic with the generation of reactive oxygen species catalyzed by MnO_x, double hits cancer cells to release abundant tumor-associated antigens for further promoting immune response stimulation. The local anti-TNBC efficacy of photothermal/immuno-therapy has been proven effective in subcutaneous 4T1-bearing mice. Especially, it has been systematically demonstrated in bilateral orthotopic 4T1-bearing mice that the as-proposed treatment could successfully activate innate and adaptive immunity, and local therapy could engender systemic responses to suppress the distant tumors. Collectively, this work represents a proof-of-concept for a non-invasive Mn-based tumor-immunotherapeutic modality, providing a paradigm for the immunotherapy of metastatic-prone tumors.

Polymorphs and solid solutions: materials with new luminescent properties obtained through mechanochemical transformation of dicyanoaurate(I) salts

We report the use of mechano- and thermochemical methods to create new solid-state luminescent materials from well-known inorganic salts, potassium dicyanoaurate(I) KAu(CN)₂, and potassium dicyanocuprate(I) KCu(CN)₂. In particular, manual grinding or ball milling of commercial samples of KAu(CN)₂ led to the formation of a novel polymorph of the salt, herein termed m-KAu(CN)₂, evident by a significant change in color of the fluorescence emission of the solid material from orange to violet. The formation of m-KAu(CN)₂ is reversible upon addition of small amounts of solvents, and powder X-ray diffraction analysis indicates that the structure of m-KAu(CN)₂ might be related to that of pristine KAu(CN)₂ through a change in ordering of Au(CN)₂^- ions in a layered structure. Thermal treatment of KAu(CN)₂ led to the discovery of another polymorph of this well-known salt, herein termed t-KAu(CN)₂, making KAu(CN)₂ a rare example of a system in which thermochemical and mechanochemical treatments lead to the formation of different, in each case previously not reported, polymorphic forms. The thermally-induced transformation from KAu(CN)₂ to t-KAu(CN)₂ takes place around 250 °C and proceeds in a crystal-to-crystal fashion, which enabled the preliminary structural characterisation through single crystal X-ray diffraction, revealing the retention of the layered structure and a change in ordering of Au(CN)₂^- ions. Milling of the simple salt KAu(CN)₂ in the presence of equimolar amounts or less of its copper(I)-based analogue coordination polymer KCu(CN)₂ leads to the formation of a series of solid solution materials, isostructural to m-KAu(CN)₂ and with visible fluorescence emission distinct from KCu(CN)₂ or any herein investigated forms of KAu(CN)₂.

2D Network overtakes 3D for photocatalytic hydrogen evolution

3-Dimensional (3D) cyanide coordination polymers, typically known as Prussian blue Analogues (PBAs), have received great attention in catalysis due to their stability, easily tuned metal sites, and porosity. However, their high crystallinities and relatively low number of surface-active sites significantly hamper their intrinsic catalytic activities. Herein, we report the utilization of a 2-dimensional (2D) layered cobalt tetracyanonickelate, [Co-Ni], for the reduction of protons to H₂. Relying on its exposed facets, layered morphology, and abundant surface-active sites, [Co-Ni] can efficiently convert water and sunlight to H₂ in the presence of a ruthenium photosensitizer (Ru PS) with an optimal evolution rate of 30 029 ± 590 μmol g^-1 h^-1, greatly exceeding that of 3D Co-Fe PBA [Co-Fe] and Co-Co PBA [Co-Co]. Furthermore, [Co-Ni] retains its structural integrity throughout a 6 hour photocatalytic cycle, which is confirmed by XPS, PXRD, and Infrared analysis. This recent work reveals the excellent morphologic properties that promote [Co-Ni] as an attractive catalyst for the hydrogen evolution reaction (HER).

Uncovering the Interplay of Competing Distortions in the Prussian Blue Analogue K2Cu[Fe(CN)6]

We report the synthesis, crystal structure, thermal response, and electrochemical behavior of the Prussian blue analogue (PBA) K₂Cu[Fe(CN)₆]. From a structural perspective, this is the most complex PBA yet characterized: its triclinic crystal structure results from an interplay of cooperative Jahn-Teller order, octahedral tilts, and a collective "slide" distortion involving K-ion displacements. These different distortions give rise to two crystallographically distinct K-ion channels with different mobilities. Variable-temperature X-ray powder diffraction measurements show that K-ion slides are the lowest-energy distortion mechanism at play, as they are the only distortion to be switched off with increasing temperature. Electrochemically, the material operates as a K-ion cathode with a high operating voltage and an improved initial capacity relative to higher-vacancy PBA alternatives. On charging, K⁺ ions are selectively removed from a single K-ion channel type, and the slide distortions are again switched on and off accordingly. We discuss the functional importance of various aspects of structural complexity in this system, placing our discussion in the context of other related PBAs.

N-Doped hollow Fe0.4Co0.6S2@NC nanoboxes derived from a Prussian blue analogue as a sodium ion anode

Herein, a bimetallic sulfide Fe_0.4Co_0.6S₂@NC nanobox was prepared via a simple two-step synthetic route. The N-doped carbon coated hollow nanobox was derived from a Prussian blue analogue (PBA) and applied for an SIB anode. As expected, it exhibits a high capacity (486.6 mA h g^-1 at 0.1 A g^-1) and displays an excellent cycling stability (230 mA h g^-1 at 10 A g^-1 after 900 cycles).

Degradable Magnetic Nanoplatform with Hydroxide Ions Triggered Photoacoustic, MR Imaging, and Photothermal Conversion for Precise Cancer Theranostic

Theranostic agents based on inorganic nanomaterials are still suffered from the nonbiodegradable substances with long-term retention in body and unavoidable biological toxicity, as well as nonspecificity biodistribution with potential damage toward normal tissues. Here, we develop magnetic ions (Fe^III, Fe^II, Gd^III, Mn^II, and Mn^III) coordinated nanoplatform (MICN) with framework structure and modify them with PEG (MICN-PEG). Notably, MICN-PEG demonstrates hydroxide ions (OH^-) triggered the structure collapse along with responsive near-infrared photoacoustic (PA) signal, magnetic resonance imaging (MRI), and photothermal therapy (PTT) performances. Thereby, MICN-PEG is able to remain stable in tumors and exert excellent PA/MRI and PTT effects for multimodal imaging-guided cancer treatment. In contrast, MICN-PEG is gradually collapsed in normal tissues, resulting in the significant improvement of imaging accuracy and treatment specificity. MICN-PEG is gradually cleared after administration, minimizing concerns about the long-term toxicity.