Dynamic Phase Transformations of Prussian Blue Analogue Crystals in Hydrotherms.

Prussian blue analogue (PBA)/metal-organic frameworks (MOFs) are multifunctional precursors for the synthesis of metal/metal compounds, carbon, and their derived composites (P/MDCs) in chemical, medical, energy, and other applications. P/MDCs combine the advantages of both the high specific surface area of PBA/MOF and the electronic conductivity of metal compound/carbon. Although the calcination under different atmospheres has been extensively studied, the transformation mechanism of PBA/MOF under hydrothermal conditions remains unclear. The qualitative preparation of P/MDCs in hydrothermal conditions remains a challenge. Here, we select PBA to construct a machine-learning model and measure its hydrothermal phase diagram. The architecture-activity relationship of substances among nine parameters was analyzed for the hydrothermal phase transformation of PBA. Excitingly, we established a universal qualitative model to accurately fabricate 31 PBA derivates. Additionally, we performed three-dimensional reconstructed transmission electron microscopy, X-ray absorption fine structure spectroscopy, ultraviolet photoelectron spectroscopy, in situ X-ray powder diffraction, and theoretical calculation to analyze the advantages of hydrothermal derivatives in the oxygen evolution reaction and clarify their reaction mechanisms. We uncover the unified principles of the hydrothermal phase transformation of PBA, and we expect to guide the design for a wide range of composites.

In Situ Phosphorization for Constructing Ni5P2-Ni Heterostructure Derived from Bimetallic MOF for Li-S Batteries.

Heterostructured materials commonly consist of bifunctions due to the different ingredients. For host material in the sulfur cathode of lithium-sulfur (Li-S) batteries, the chemical adsorption and catalytic activity for lithium polysulfides (LiPS) are important. This work obtains a Ni5P2-Ni nanoparticle (Ni5P2-NiNPs) heterostructure through a confined self-reduction method followed by an in situ phosphorization process using Al/Ni-MOF as precursors. The Ni5P2-Ni heterostructure not only has strong chemical adsorption, but also can effectively catalyze LiPS conversion. Furthermore, the synthetic route can keep Ni5P2-NiNPs inside of the nanocomposites, which have structural stability, high conductivity, and efficient adsorption/catalysis in LiPS conversion. These advantages make the assembled Li-S battery deliver a reversible specific capacity of 619.7 mAh g- 1 at 0.5 C after 200 cycles. The in situ ultraviolet-visible technique proves the catalytic effect of Ni5P2-Ni heterostructure on LiPS conversion during the discharge process.

Steerable Interfacial Assembly of 1D Amyloid-Like Protein Nanocomposites for Enhanced Nanoherbicide Utilization.

Conventional herbicide formulations suffer from serious problems such as easy drift, run-off and scouring into the environment, which pose enormous threats to human health and environmental safety. Herein, an innovative strategy is proposed to prepare oil-in-water nanoemulsions with long-term stability, enhanced droplet deposition, and improved nanoherbicide adhesion via steerable interfacial assembly of 1D amyloid-like protein nanocomposites. Bovine serum albumin (BSA) undergoes rapid amyloid-like aggregation upon reduction of its disulfide bond. The resulting phase-transitioned BSA (PTB) oligomers instantly self-assemble on the surface of cellulose nanofibers (CNF) to form the 1D PTB/CNF nanocomposites, which greatly expands the parameter space for interfacial assembly of amyloid-like proteins. The PTB/CNF nanocomposites exhibit excellent interfacial activity, enabling spontaneous adsorption at the oil-water interface to stabilize nanoemulsion. The excess PTB/CNF nanocomposites would also self-assemble at the air-aqueous interface upon spraying, resulting in efficient droplet deposition on (super)hydrophobic leaves. The deposited nanoherbicides show excellent resistance to wind/rain corrosion due to the robust amyloid-mediated adhesion, with a retention rate of more than 80% after severe scouring. Consequently, herbicide applications can be reduced by at least 30% compared to commercial emulsifiable concentrates, showing greater herbicidal efficiency. This study provides novel insights and approaches to promote sustainable agricultural development.

Biomimetic Mineralization Synthesis of Flower-Like Cobalt Selenide/Reduced Graphene Oxide for Improved Electrochemical Deionization.

Rationally and precisely tuning the composition and structure of materials is a viable strategy to improve electrochemical deionization (EDI) performances, which yet faces enormous challenges. Herein, an eco-friendly biomimetic mineralization synthetic strategy is developed to synthesize the flower-like cobalt selenide/reduced graphene oxide (Bio-CoSe2/rGO) composites and used as advanced sodium ion adsorption electrodes. Benefiting from the slow and controllable reaction kinetics provided by the biomimetic mineralization process, the flower-like CoSe2 is uniformly constructed in the rGO, which is endowed with robust architecture, substantial adsorption sites and rapid charge/ion transport. The Bio-CoSe2/rGO electrode yields the maximum salt adsorption capacity and salt adsorption rate of 56.3 mg g-1 and 5.6 mg g-1 min-1 respectively, and 92.5% capacity retention after 60 cycles. These results overmatch the pristine CoSe2 and irregular granular CoSe2/rGO synthesized by a hydrothermal method, proving the structural superiority of the Bio-CoSe2/rGO composites. Furthermore, the in-depth adsorption kinetics study indicates the chemisorption nature of sodium ion adsorption. The structures of the Bio-CoSe2/rGO composites after long term EDI cycles are intensively studied to unveil the mechanism behind such superior EDI performances. This study offers one effective method for constructing advanced EDI electrodes, and enriches the application of the biomimetic mineralization synthetic strategy.

Deliberate Amorphization of Co-MOF for Constructing Crystalline-Amorphous Heterostructures Toward High-Performance Water Electrolysis.

The endowment of metal organic frameworks (MOF) with superior electrocatalytic performance without compromising their structural/compositional superiorities is of great significance for the development of renewable energy devices, yet remains a grand challenge. Herein, a deliberate partial amorphization strategy is developed to construct a heterostructured electrocatalyst consisting of crystalline Co-MOF and amorphous Co-S nanoflake arrays aligned on the carbon cloth (CC) substrate (abbreviated as Co-MOF/Co-S@CC hereafter) through a rapid sulfuration method. The simultaneous implement of crystalline-amorphous (c-a) heterostructure and nanoflake arrayed architecture on CC substrate renders the Co-MOF/Co-S@CC with abundant and tight active sites, accelerated charge transfer rate, regulated electronic structures, and reinforced structural stability. As such, the obtained Co-MOF/Co-S@CC electrode demonstrates outstanding electrochemical hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performances with the overpotentials of 64 and 217 mV at 10 mA cm-2, respectively. Moreover, a two-electrode electrolyzer assembled by Co-MOF/Co-S@CC electrodes exhibits the lower cell voltages and larger current densities than those of Pt/C and RuO2 counterparts, excellent reversibility and prominent long-term stability, representing a great prospect for feasible H2 production. This adopted concept of c-a heterostructure for electronic regulation may bring about insightful inspiration for designing high-performance electrocatalysts for sustainable energy systems.

3D Printed MXene-Based Wire Strain Sensors with Enhanced Sensitivity and Anisotropy.

Stretchable strain sensors play a crucial role in intelligent wearable systems, serving as the interface between humans and environment by translating mechanical strains into electrical signals. Traditional fiber strain sensors with intrinsic uniform axial strain distribution face challenges in achieving high sensitivity and anisotropy. Moreover, existing micro/nano-structure designs often compromise stretchability and durability. To address these challenges, a novel approach of using 3D printing to fabricate MXene-based flexible sensors with tunable micro and macrostructures.  Poly(tetrafluoroethylene) (PTFE) as a pore-inducing agent is added into 3D printable inks to achieve controllable microstructural modifications. In addition to microstructure tuning, 3D printing is employed for macrostructural design modifications, guided by finite element modeling (FEM) simulations. As a result, the 3D printed sensors exhibit heightened sensitivity and anisotropy, making them suitable for tracking static and dynamic displacement changes. The proposed approach presents an efficient and economically viable solution for standardized large-scale production of advanced wire strain sensors.

Recent Progress in 2D Metal-Organic Framework-Related Materials.

2D metal-organic frameworks-based (2D MOF-related) materials benefit from variable topological structures, plentiful open active sites, and high specific surface areas, demonstrating promising applications in gas storage, adsorption and separation, energy conversion, and other domains. In recent years, researchers have innovatively designed multiple strategies to avoid the adverse effects of conventional methods on the synthesis of high-quality 2D MOFs. This review focuses on the latest advances in creative synthesis techniques for 2D MOF-related materials from both the top-down and bottom-up perspectives. Subsequently, the strategies are categorized and summarized for synthesizing 2D MOF-related composites and their derivatives. Finally, the current challenges are highlighted faced by 2D MOF-related materials and some targeted recommendations are put forward to inspire researchers to investigate more effective synthesis methods.

Double-Shelled Open Hollow Metal-Organic Frameworks for Efficient Aqueous Zn-Ion Batteries.

Multi-shelled hollow metal-organic frameworks (MH-MOFs) are highly promising as electrode materials due to their impressive surface area and efficient mass transfer capabilities. However, the fabrication of MH-MOFs has remained a formidable challenge. In this study, two types of double-shelled open hollow Prussian blue analogues, one with divalent iron (DHPBA-Fe(II)) and the other with trivalent iron (DHPBA-Fe(III)), through an innovative inner-outer growth strategy are successfully developed. The growth mechanism is found to involve lattice matching growth and ligand exchange processes. Subsequently, DHPBA-Fe(II) and DHPBA-Fe(III) are employed as cathodes in aqueous Zn-ion batteries. Significantly, DHPBA-Fe(II) demonstrated exceptional performance, exhibiting a capacity of 92.5 mAh g-1 at 1 A g-1, and maintaining remarkable stability over an astounding 10 000 cycles. This research is poised to catalyze further exploration into the fabrication techniques of MH-MOFs and offer fresh insights into the intricate interplay between electronic structure and battery performance.

Two-Dimensional (2D) Conductive Metal-Organic Framework Thin Films: The Preparation and Applications in Electrochemistry.

Two-dimensional conductive MOF thin films have attracted attention due to their rich pore structure and unique electrical properties, and their applications in many fields, including batteries, sensing, supercapacitors, electrocatalysis, etc. This paper discusses several preparation methods for 2D conductive MOF thin films. And the applications of 2D conductive MOF thin films are summarized. In addition, the current challenges in the preparation of 2D conductive MOF thin films and the great potential in practical applications are discussed.

Conductive Metal-Organic Framework Grown on the Nickel-Based Hydroxide to Realize High-Performance Electrochemical Glucose Sensing.

Glucose holds significant importance in disease diagnosis as well as beverage quality monitoring. The high-efficiency electrochemical sensor plays a crucial role in the electrochemical conversion technology. Ni(OH)2 nanosheets are provided with high specific surface area and redox activity that are widely used in electrochemistry. Conductive metal-organic frameworks (cMOFs) perfectly combine the structural controllability of organic materials with the long-range ordering of inorganic materials that possess the characteristic of high electron mobility. Based on the above considerations, the combination of Ni(OH)2 and Ni-HHTP (HHTP=2,3,6,7,10,11-hexahydroxytriphenylene) as an electrode modification material is designed to enhance electrochemical performance. In this work, to improve glucose detection, a sequence of Ni(OH)2@NiCo-HHTP and NiM-LDH@Ni-HHTP (M=Co2+, Mn2+, Cu2+, LDH=layered double hydroxide) are successfully synthesised by doping metals into Ni-HHTP and Ni(OH)2, respectively. As a result, NiCu-LDH@Ni-HHTP showed the best excellent glucose detection sensitivity.