Engineering Metal–Phenolic Networks for Solar Desalination with Directional Salt Crystallization

Solar desalination is one of the most promising strategies to address the global freshwater shortage crisis. However, the residual salt accumulated on the top surface of solar evaporators severely reduces light absorption and steam evaporation efficiency, thus impeding the further industrialization of this technology. Herein, a metal–phenolic network (MPN)-engineered 3D evaporator composed of photothermal superhydrophilic/superhydrophobic sponges and side-twining hydrophilic threads for efficient desalination with directional salt crystallization and zero liquid discharge is reported. The MPN coatings afford the engineering of alternating photothermal superhydrophilic/superhydrophobic sponges with high heating efficiency and defined vapor escape channels, while the side-twining threads induce site-selective salt crystallization. The 3D evaporator exhibits a high and stable indoor desalination rate (≈2.3 kg m⁻² h⁻¹) of concentrated seawater (20 wt%) under simulated sun irradiation for over 21 days without the need for salt crystallization inhibitors. This direct desalination is also achieved in outdoor field operations with a production rate of clean water up to ≈1.82 kg m⁻² h⁻¹ from concentrated seawater (10 wt%). Together with the high affinity and multiple functions of MPNs, this work is expected to facilitate the rational design of solar desalination devices and boost the research translation of MPN materials in broader applications.     

A Metal–Polyphenol-Coordinated Nanomedicine for Synergistic Cascade Cancer Chemotherapy and Chemodynamic Therapy

The clinical application of chemotherapy is impeded by the unsatisfactory efficacy and severe side effects. Chemodynamic therapy (CDT) has emerged as an efficient strategy for cancer treatment utilizing Fenton chemistry to destroy cancer cells by converting endogenous H₂O₂ into highly toxic reactive oxygen species. Apart from the chemotherapeutic effect, cisplatin is able to act as an artificial enzyme to produce H₂O₂ for CDT through cascade reactions, thus remarkably improving the anti-tumor outcomes. Herein, an organic theranostic nanomedicine (PTCG NPs) is constructed with high loading capability using epigallocatechin-3-gallate (EGCG), phenolic platinum(IV) prodrug (Pt-OH), and polyphenol modified block copolymer (PEG-b-PPOH) as the building blocks. The high stability of PTCG NPs during circulation stems from their strong metal–polyphenol coordination interactions, and efficient drug release is realized after cellular internalization. The activated cisplatin elevates the intracellular H₂O₂ level through cascade reactions. This is further utilized to produce highly toxic reactive oxygen species catalyzed by an iron-based Fenton reaction. In vitro and in vivo investigations demonstrate that the combination of chemotherapy and chemodynamic therapy achieves excellent anticancer efficacy. Meanwhile, systemic toxicity faced by platinum-based drugs is avoided through this nanoformulation. This work provides a promising strategy to develop advanced nanomedicine for cascade cancer therapy.     

A Self-Templated Design Approach toward Multivariate Metal–Organic Frameworks for Enhanced Oxygen Evolution

Multivariate metal–organic framework (MOF) is an ideal electrocatalytic material due to the synergistic effect of multiple metal active sites. In this study, a series of ternary M-NiMOF (M = Co, Cu) through a simple self-templated strategy that the Co/Cu MOF isomorphically grows in situ on the surface of NiMOF is designed. Owing to the electron rearrange of adjacent metals, the ternary CoCu-NiMOFs demonstrate the improved intrinsic electrocatalytic activity. At optimized conditions, the ternary Co₃Cu-Ni₂MOFs nanosheets give the excellent oxygen evolution reaction (OER) performance of current density of 10 mA cm⁻² at low overpotential of 288 mV with a Tafel slope of 87 mV dec⁻¹, which is superior to that of bimetallic nanosheet and ternary microflowers. The low free energy change of potential-determining step identifies that the OER process is favorable at Cu–Co concerted sites along with strong synergistic effect of Ni nodes. Partially oxidized metal sites also reduce the electron density, thus accelerating the OER catalytic rate. The self-templated strategy provides a universal tool to design multivariate MOF electrocatalysts for highly efficient energy transduction.     

Hierarchical and Orderly Surface Conductive Networks in Yolk–Shell Fe3O4@C@Co/N-Doped C Microspheres for Enhanced Microwave Absorption

Constructing the adjustable surface conductive networks is an innovation that can achieve a balance between enhanced attenuation and impedance mismatch according to the microwave absorption mechanism. However, the traditional design strategies remain significant challenges in terms of rational selection and controlled growth of conductive components. Herein, a hierarchical construction strategy and quantitative construction technique are employed to introduce conductive metal–organic frameworks (MOFs) derivatives in the classic yolk–shell structure composed of electromagnetic components and the cavity for remarkable optimized performance. Specifically, the surface conductive networks obtained by carbonized ZIF-67 quantitative construction, together with the Fe₃O₄ magnetic core and dielectric carbon layer linked by the cavity, achieve the cooperative enhancement of impedance matching optimization and synergistic attenuation in the Fe₃O₄@C@Co/N-Doped C (FCCNC) absorber. This interesting design is further verified by experimental results and simulation calculations. The products FCCNC-2 yield a distinguished minimum reflection loss of −66.39 dB and an exceptional effective absorption bandwidth of 6.49 GHz, indicating that moderate conduction excited via hierarchical and quantitative design can maximize the absorption capability. Furthermore, the proposed versatile methodology of surface assembly paves a new avenue to maximize beneficial conduction effect and manipulate microwave attenuation in MOFs derivatives.     

Microenvironment Modulation of Metal–Organic Frameworks (MOFs) for Coordination Olefin Oligomerization and (co)Polymerization

The majority of commercial polyolefins are produced by coordination polymerization using early or late transition metal catalysts. Molecular catalysts containing these transition metals (Ti, Zr, Cr, Ni, and Fe, etc.) are loaded on supports for controlled polymerization behavior and polymer morphology in slurry or gas phase processes. Within the last few years, metal–organic frameworks (MOFs), a class of unique porous crystalline materials constructed from metal ions/clusters and organic ligands, have been designed and utilized as excellent supports for heterogeneous polymerization catalysis whose high density and uniform distribution of active sites would benefit the modulations of molecular weight distributions of high-performance olefin oligomers and (co)polymers. Impressive efforts have been made to modulate the microenvironment surrounding the active centers at the atomic level for improved activities of MOFs-based catalysts and controlled selectivity of olefin insertion. This review aims to draw a comprehensive picture of MOFs for coordination olefin oligomerization and (co)polymerization in the past decades with respect to different transition metal active centers, various incorporation sites, and finally microenvironment modulation. In consideration of more efforts are needed to overcome challenges for further industrial and commercial application, a brief outlook is provided.     

A Metal–Organic Frameworks Derived 1T-MoS2 with Expanded Layer Spacing for Enhanced Electrocatalytic Hydrogen Evolution

Metal phase molybdenum disulfide (1T-MoS₂) is considered a promising electrocatalyst for hydrogen evolution reaction (HER) due to its activated basal and superior electrical conductivity. Here, a one-step solvothermal route is developed to prepare 1T-MoS₂ with expanded layer spacing through the derivatization of a Mo-based organic framework (Mo-MOFs). Benefiting from N,N-dimethylformamide oxide as external stress, the interplanar spacing of (002) of the MoS₂ catalyst is extended to 10.87 Å, which represents the largest one for the 1T-MoS₂ catalyst prepared by the bottom-up approach. Theoretical calculations reveal that the expanded crystal planes alter the electronic structure of 1T-MoS₂, lower the adsorption–desorption potentials of protons, and thus, trigger efficient catalytic activity for HER. The optimal 1T-MoS₂ catalyst exhibits an overpotential of 98 mV at 10 mA cm⁻² for HER, corresponding to a Tafel slope of 52 mV dec⁻¹. This Mo-MOFs-derived strategy provides a potential way to design high-performance catalysts by adjusting the layer spacing of 2D materials.     

Plasmonic Metal Mediated Charge Transfer in Stacked Core–Shell Semiconductor Heterojunction for Significantly Enhanced CO2 Photoreduction

Construction of core–shell semiconductor heterojunctions and plasmonic metal/semiconductor heterostructures represents two promising routes to improved light harvesting and promoted charge separation, but their photocatalytic activities are respectively limited by sluggish consumption of charge carriers confined in the cores, and contradictory migration directions of plasmon-induced hot electrons and semiconductor-generated electrons. Herein, a semiconductor/metal/semiconductor stacked core–shell design is demonstrated to overcome these limitations and significantly boost the photoactivity in CO₂ reduction. In this smart design, sandwiched Au serves as a “stone”, which “kills two birds” by inducing localized surface plasmon resonance for hot electron generation and mediating unidirectional transmission of conduction band electrons and hot electrons from TiO₂ core to MoS₂ shell. Meanwhile, upward band bending of TiO₂ drives core-to-shell migration of holes through TiO₂–MoS₂ interface. The co-existence of TiO₂ → Au → MoS₂ electron flow and TiO₂ → MoS₂ hole flow contributes to spatial charge separation on different locations of MoS₂ outer layer for overall redox reactions. Additionally, reduction potential of photoelectrons participating in the CO₂ reduction is elaborately adjusted by tuning the thickness of MoS₂ shell, and thus the product selectivity is delicately regulated. This work provides fresh hints for rationally controlling the charge transfer pathways toward high-efficiency CO₂ photoreduction.     

Tumor-Microenvironment-Triggered Ion Exchange of a Metal–Organic Framework Hybrid for Multimodal Imaging and Synergistic Therapy of Tumors

Nanotheranostic agents (NTAs) that integrate diagnostic capabilities and therapeutic functions have great potential for personalized medicine, yet poor tumor specificity severely restricts further clinical applications of NTAs. Here, a pro-NTA (precursor of nanotheranostic agent) activation strategy is reported for in situ NTA synthesis at tumor tissues to enhance the specificity of tumor therapy. This pro-NTA, also called PBAM, is composed of an MIL-100 (Fe)-coated Prussian blue (PB) analogue (K₂Mn[Fe(CN)₆]) with negligible absorption in the near-infrared region and spatial confinement of Mn²⁺ ions. In a mildly acidic tumor microenvironment (TME), PBAM can be specifically activated to synthesize the photothermal agent PB nanoparticles, with release of free Mn²⁺ ions due to the internal fast ion exchange, resulting in the “ON” state of both T₁-weighted magnetic resonance imaging and photoacoustic signals. In addition, the combined Mn²⁺-mediated chemodynamic therapy in the TME and PB-mediated photothermal therapy guarantee a more efficient therapeutic performance compared to monotherapy. In vivo data further show that the pro-NTA activation strategy could selectively brighten solid tumors and detect invisible lymph node metastases with high specificity.     

PEGylated Manganese–Zinc Ferrite Nanocrystals Combined with Intratumoral Implantation of Micromagnets Enabled Synergetic Prostate Cancer Therapy via Ferroptotic and Immunogenic Cell Death (Small 22/2023)

Therapeutic efficacy for prostate cancer is highly restricted by insufficient drug accumulation and the resistance to apoptosis and immunogenic cell death (ICD). Although enhanced permeability and retention (EPR) effect of magnetic nanomaterials could benefit from external magnetic field, it falls off rapidly with increased distance from magnet surface. Considering the deep location of prostate in pelvis, the improvement of EPR effect by external magnetic field is limited. In addition, apoptosis resistance and cGAS-STING pathway inhibition-related immunotherapy resistance are major obstacles to conventional therapy. Herein, the magnetic PEGylated manganese-zinc ferrite nanocrystals (PMZFNs) are designed. Instead of providing external magnet, micromagnets into tumor tissues are intratumorally implanted to actively attract and retain intravenously-injected PMZFNs. As a result, PMZFNs accumulate in prostate cancer with high efficacy, depending on the established internal magnetic field, which subsequently elicit potent ferroptosis and the activation of cGAS-STING pathway. Ferroptosis not only directly suppresses prostate cancer but also triggers burst release of cancer-associated antigens and consequently initiates ICD against prostate cancer, where activated cGAS-STING pathway further amplifies the efficacy of ICD by generating interferon-β. Collectively, the intratumorally implanted micromagnets confer a durable EPR effect of PMZFNs, which eventually achieve the synergetic tumoricidal efficacy with negligible systemic toxicity.     

Magnetic properties of Ni(II)–Mn(III) LDHs

The synthesis of Ni_1−xMn_x(OH)₂(CO₃)_x/2·nH₂O Layered Double Hydroxides (LDHs) for x = 0.2, 0.25 and 0.33, their characterisation by electron microscopy, X-ray diffraction and their magnetic properties are reported in this study. When x increases, the crystallinity of the nanoparticles is improved. The low temperature magnetic behaviour of these compounds is characteristic of the competition between in plane ferromagnetic and interlayer antiferromagnetic interactions. The ferromagnetism is due to in plane Ni cations interaction and decreases when manganese content increases (Tc decreases from 26 to 15 K when x increases from 0.2 to 0.33). It was found that the substitution of Ni by Mn ions favours the in plane antiferromagnetic order. This study demonstrates that magnetic interactions occur in LDH with non magnetic interlayer anions.     

Cobalt-Exchanged Poly(Heptazine Imides) as Transition Metal–Nx Electrocatalysts for the Oxygen Evolution Reaction

Poly(heptazine imides) hosting cobalt ions as countercations are presented as promising electrocatalysts for the oxygen evolution reaction (OER). A facile mixed-salt melt-assisted condensation is developed to prepare such cobalt poly(heptazine imides) (PHI-Co). The Co ions can be introduced in well-controlled amounts using this method, and are shown to be atomically dispersed within the imide-linked heptazine matrix. When applied to electrocatalytic OER, PHI-Co shows a remarkable activity with an overpotential of 324 mV and Tafel slope of 44 mV dec⁻¹ in 1 m KOH.     

Processing map for hot working of Ni–16Cr–8Fe alloy (IN 600)

Abstract

The hot deformation characteristics of IN 600 nickel alloy are studied using hot compression testing in the temperature range 850–1200°C and strain rate range 0·001–100 s^?l. A processing map for hot working is developed on the basis of the data obtained, using the principles of dynamic materials modelling. The map exhibits a single domain with a peak efficiency of power dissipation of 48% occurring at 1200°C and 0·2 s^?1, at which the material undergoes dynamic recrystallisation (DRX). These are the optimum conditions for hot working of IN 600. At strain rates higher than 1 s^?1, the material exhibits flow localisation and its microstructure consists of localised bands of fine recrystallised grains. The presence of iron in the Ni–Cr alloy narrows the DRX domain owing to a higher temperature required for carbide dissolution, which is essential for the occurrence of DRX. The efficiency of DRX in Ni–Cr is, however, enhanced by iron addition.

MST/1856     

Leveraging Ligand and Composition Effects: Morphology-Tailorable Pt–Bi Bimetallic Aerogels for Enhanced (Photo-)Electrocatalysis

Metal aerogels (MAs) are emerging porous materials displaying unprecedented potential in catalysis, sensing, plasmonic technologies, etc. However, the lack of efficient regulation of their nano-building blocks (NBBs) remains a big hurdle that hampers the in-depth investigation and performance enhancement. Here, by harmonizing composition and ligand effects, Pt- and Bi-based single- and bimetallic aerogels bearing NBBs of controlled dimensions and shapes are obtained by facilely tuning the metal precursors and the applied ligands. Particularly, by further modulating the electronic and optic properties of the aerogels via adjusting the content of the catalytically active Pt component and the semiconducting Bi component, both the electrocatalytic and photoelectrocatalytic performance of the Pt–Bi aerogels can be manipulated. In this light, an impressive catalytic performance for electro-oxidation of methanol is acquired, marking a mass activity of 6.4-fold higher under UV irradiation than that for commercial Pt/C. This study not only sheds light on in situ manipulating NBBs of MAs, but also puts forward guidelines for crafting high-performance MAs-based electrocatalysts and photoelectrocatalysts toward energy-related electrochemical processes.     

Homogeneous nanocube (Fe,Ni) S2 electrode material from Fe–Ni PBA for high-performance hybrid supercapacitors

Journal of Materials Science: Materials in Electronics - Prussian blue analogs (PBAs) are multifunctional precursors for the synthesis of a series of transition metal nanomaterials. In this study,...     

A novel lutetium(III) PVC membrane sensor based on a new symmetric S–N Schiff's base for Lu(III) analysis in real sample

A novel Lu(III) PVC membrane sensor has been constructed based on a new synthesized symmetric S–N Schiff's base, namely N-[(Z)-1-(2-thienyl)methylidene]-N-[4-(4-{[(Z)-1-(2-thienyl) methylidene]amino}benzyl)phenyl] amine (TBPA). The electrode showed a Nernstian slope of 19.8 ± 0.5 mV per decade across a wide concentration range of 1.0 × 10^? 6 to 1.0 × 10^? 2 mol L^? 1 with a detection limit of 7.2 × 10^? 7 mol L^? 1. The proposed sensor showed high selectivity toward Lu(III) ion in comparison with common alkaline, alkaline earth, transition, and heavy metals specially lanthanide ions, and could be used over a pH range of 2.7–10.6. It can be used for at least 2 months without any considerable divergency in potentials and it has a relatively fast response time of < 10 s. The sensor was effectively used as an indicator electrode in the potentiometric titration of Lu(III) ions with EDTA. The constructed sensor accuracy was investigated by the monitoring of Lu(III) ion in mixtures of two and three different ions.     

Enhanced optoelectronics properties of europium(III) complexes with β-diketone and nitrogen heterocyclic ligands

Preparation and photoluminescence behavior of six new europium complexes with β-diketone 1-(2-hydroxy phenyl)-3-phenylpropane-1,3-dione (HPPP) and bathophenanthroline (batho), 2,2′-bipyridyl (bipy), 2,2′-biquinoline (biq), neocuproin (neo) and 1,10-phenanthroline (phen) are reported in solid state. The ligand (HPPP) and complexes Eu(HPPP)₃·H₂O (1), Eu(HPPP)₃·phen (2), Eu(HPPP)₃·batho (3), Eu(HPPP)₃·bipy (4), Eu(HPPP)₃·biq (5) and Eu(HPPP)₃·neo (6) were characterized by means of elemental analysis, infrared spectroscopy, proton nuclear magnetic resonance (¹H-NMR). The optical properties, thermal stability and crystalline nature were investigated by photoluminescence spectroscopy, thermogravimetric analysis and XRD respectively. The emission spectra show narrow intense emission band of central europium (III) metal ion that arise from the high intense ⁵D₀ → ⁷F₀ transition. The introduction of ancillary ligands like batho, bipy, biq, neo, phen enlarged the π-conjugation system in complexes as a result higher luminescence intensity, longer life time (τ) and higher quantum efficiency (η) observed in europium ternary complexes in comparison to Eu(HPPP)₃·H₂O (1). Based on the emission spectra, the luminescence decay curve was measured which indicated that the transfer of energy from HPPP ligand to the europium metal is more efficient in complexes 2–6 than complex 1.     

Investigation of sorbents synthesised by mechanical–chemical reaction for sorption of As(III) and As(V) from aqueous medium

Efficiency of Fe₂O₃ and mixture of Fe₂O₃ and MnO₂ nanoparticles synthesised by mechanical–chemical reaction for inorganic As(III) and As(V) sorption was examined. Sorbents (Fe₂O₃ and mixture Fe₂O₃:MnO₂ = 3:1) synthesised by mechanical–chemical treatment in planetary ball mile with different milling times were tested by batch experiments. Experimental data were fitted both to Freundlich and Langmuir adsorption models. Efficiency of sorption was in good correlation with the time of milling in case of pure oxide. There were small differences in sorption between As(III) and As(V). In the case of mixture of oxides results were different. The best results were obtained by 30 min of milling. With prolonged milling, the sorption decreased to 3 h and after that increased again. These results were explained by phase transition. Sorption kinetics, influence of pH and the presence of other anions were examined for mixture of oxides with highest sorption capacity. The bioavailability of sorbed arsen was tested using modified Tessier procedure.