Unveiling the Advances of Nanostructure Design for Alloy-Type Potassium-Ion Battery Anodes via In Situ TEM

Nanostructure design and in situ transmission electron microscopy (TEM) are combined to demonstrate Sb-based nanofibers composed of bunched yolk–shell building units as a significantly improved anode for potassium-ion batteries (PIBs). Particularly, a metal–organic frameworks (MOFs)-engaged electrospinning strategy coupled to a confined ion-exchange followed by a subsequent thermal reduction is proposed to fabricate yolk–shell Sb@C nanoboxes embedded in carbon nanofibers (Sb@CNFs). In situ TEM analysis reveals that the inner Sb nanoparticles undergo a significant volume expansion/contraction during the alloying/dealloying processes, while the void space can effectively relieve the overall volume change, and the plastic carbon shell maintains the structural integrity of electrode material. This work provides an important reference for the application of advanced characterization techniques to guide the optimization of electrode material design.     

Modulating Cell‐Surface Receptor Signaling and Ion Channel Functions by In Situ Glycan Editing

Glycans anchored on cell‐surface receptors are active modulators of receptor signaling. A strategy is presented that enforces transient changes to cell‐surface glycosylation patterns to tune receptor signaling. This approach, termed in situ glycan editing, exploits recombinant glycosyltransferases to incorporate monosaccharides with linkage specificity onto receptors in situ. α2,3‐linked sialic acid or α1,3‐linked fucose added in situ suppresses signaling through epidermal growth factor receptor and fibroblast growth factor receptor. We also applied the same strategy to regulate the electrical signaling of a potassium ion channel–human ether‐à‐go‐go‐related gene channel. Compared to gene editing, no long‐term perturbations are introduced to the treated cells. In situ glycan editing therefore offers a promising approach for studying the dynamic role of specific glycans in membrane receptor signaling and ion channel functions.     

Real‐time Observation of Deep Lithiation of Tungsten Oxide Nanowires by In Situ Electron Microscopy

An in‐depth mechanistic understanding of the electrochemical lithiation process of tungsten oxide (WO₃) is both of fundamental interest and relevant for potential applications. One of the most important features of WO₃ lithiation is the formation of the chemically flexible, nonstoichiometric Li_xWO₃, known as tungsten bronze. Herein, we achieved the real‐time observation of the deep electrochemical lithiation process of single‐crystal WO₃ nanowires by constructing in situ transmission electron microscopy (TEM) electrochemical cells. As revealed by nanoscale imaging, diffraction, and spectroscopy, it is shown that the rapid and deep lithiation of WO₃ nanowires leads to the formation of highly disordered and near‐amorphous Li_xWO₃ phases, but with no detectable traces of elemental W and segregated Li₂O phase formation. These results highlight the remarkable chemical and structural flexibility of the Li_xWO₃ phases in accommodating the rapid and deep lithiation reaction.     

Hollow Metal–Organic‐Framework‐Mediated In Situ Architecture of Copper Dendrites for Enhanced CO2 Electroreduction

Electrocatalytic reduction of CO₂ to a single product at high current densities and efficiencies remains a challenge. However, the conventional electrode preparation methods, such as drop‐casting, usually suffer from low intrinsic activity. Herein, we report a synthesis strategy for preparing heterogeneous electrocatalyst composed of 3D hierarchical Cu dendrites that derived from an in situ electrosynthesized hollow copper metal–organic framework (MOF), for which the preparation of the Cu‐MOF film took only 5 min. The synthesis strategy preferentially exposes active sites, which favor's the reduction of CO₂ to formate. The current density could be as high as 102.1 mA cm^?2 with a selectivity of 98.2 % in ionic‐liquid‐based electrolyte and a commonly used H‐type cell.     

Coordination‐Driven In Situ Self‐Assembly Strategy for the Preparation of Metal–Organic Framework Hybrid Membranes

Metal–organic frameworks (MOFs) have emerged as porous solids of a superior type for the fabrication of membranes. However, it is still challenging to prepare a uniformly dispersed robust MOF hybrid membrane. Herein, we propose a simple and powerful strategy, namely, coordination‐driven in situ self‐assembly, for the fabrication of MOF hybrid membranes. On the basis of the coordination interactions between metal ions and ligands and/or the functional groups of the organic polymer, this method was confirmed to be feasible for the production of a stable membrane with greatly improved MOF‐particle dispersion in and compatibility with the polymer, thus providing outstanding separation ability. As an experimental proof of concept, a high‐quality ZIF‐8/PSS membrane was fabricated that showed excellent performance in the nanofiltration and separation of dyes from water.     

Time‐Resolved In Situ X‐ray Diffraction Reveals Metal‐Dependent Metal–Organic Framework Formation

Versatility in metal substitution is one of the key aspects of metal‐organic framework (MOF) chemistry, allowing properties to be tuned in a rational way. As a result, it important to understand why MOF syntheses involving different metals arrive at or fail to produce the same topological outcome. Frequently, conditions are tuned by trial‐and‐error to make MOFs with different metal species. We ask: is it possible to adjust synthetic conditions in a systematic way in order to design routes to desired phases? We have used in situ X‐ray powder diffraction to study the solvothermal formation of isostructural M₂(bdc)₂dabco (M=Zn, Co, Ni) pillared‐paddlewheel MOFs in real time. The metal ion strongly influences both kinetics and intermediates observed, leading in some cases to multiphase reaction profiles of unprecedented complexity. The standard models used for MOF crystallization break down in these cases; we show that a simple kinetic model describes the data and provides important chemical insights on phase selection.     

Continuous‐Flow Synthesis of ZIF‐8 Biocomposites with Tunable Particle Size

Zeolitic imidazolate framework (ZIF) biocomposites show the capacity to protect and deliver biotherapeutics. To date, the progress in this research area is based on laboratory batch methods. Now, the first continuous flow synthetic method is presented for the encapsulation of a model protein (bovine serum albumin, BSA) and a clinical therapeutic (α1‐antitrypsin, AAT) in ZIF‐8. The in situ kinetics of nucleation, growth, and crystallization of BSA@ZIF‐8 were studied by small‐angle X‐ray scattering. By controlling the injection time of ethanol, the particle growth could be quenched by ethanol‐induced crystallization from amorphous particles to ZIF‐8 crystals. The particle size of the biocomposite was tuned in the 40–100 nm range by varying residence time prior to introduction of ethanol. As a proof‐of‐concept, this procedure was used for the encapsulation of AAT in ZIF‐8. Upon release of the biotherapeutic from the composite, the trypsin inhibitor function of AAT was preserved.     

Molecular‐Sieving Membrane by Partitioning the Channels in Ultrafiltration Membrane by In Situ Polymerization

Commercial ultrafiltration membranes have proliferated globally for water treatment. However, their pore sizes are too large to sieve gases. Conjugated microporous polymers (CMPs) feature well‐developed microporosity yet are difficult to be fabricated into membranes. Herein, we report a strategy to prepare molecular‐sieving membranes by partitioning the mesoscopic channels in water ultrafiltration membrane (PSU) into ultra‐micropores by space‐confined polymerization of multi‐functionalized rigid building units. Nine CMP@PSU membranes were obtained, and their separation performance for H₂/CO₂, H₂/N₂, and H₂/CH₄ pairs surpass the Robeson upper bound and rival against the best of those reported membranes. Furthermore, highly crosslinked skeletons inside the channels result in the structural robustness and transfer into the excellent aging resistance of the CMP@PSU. This strategy may shed light on the design and fabrication of high‐performance polymeric gas separation membranes.     

In Situ Optical Imaging of the Growth of Conjugated Polymer Aggregates

Understanding the mechanisms that contribute to conjugated polymer aggregate formation and growth may yield enhanced control of aggregate morphology and functional properties on the mesoscopic scale. In situ optical imaging of the growth of MEH‐PPV aggregates in real time in controlled swollen films shows that growth occurs through multiple mechanisms and is more complex than previously described. Direct evidence is provided for both Ostwald ripening and aggregate coalescence as operative modes of aggregate growth in solvent swollen films. These growth mechanisms have a distinct and strong impact on the evolution of morphological order of growing aggregates: while Ostwald ripening allows preservation of highly ordered morphology, aggregate coalescence occurs with no preferential orientation, leading to attenuation in degree of ordering.     

In Situ Synthesis of Self‐Assembled Gold Nanoparticles on Glass or Silicon Substrates through Reactive Inkjet Printing

A facile and low cost method for the synthesis of self‐assembled nanoparticles (NPs) with minimal size variation and chemical waste by using reactive inkjet printing was developed. Gold NPs with diameters as small as (8±2) nm can be made at low temperature (120 °C). The size of the resulting NPs can be readily controlled through the concentration of the gold precursor and oleylamine ink. The pure gold composition of the synthesized NPs was confirmed by energy‐dispersive X‐ray spectroscopy (EDXS) analysis. High‐resolution SEM (HRSEM) and TEM (HRTEM), and X‐ray diffraction revealed their size and face‐centered cubic (fcc) crystal structure, respectively. Owing to the high density of the NP film, UV/Vis spectroscopy showed a red shift in the intrinsic plasmonic resonance peak. We envision the extension of this approach to the synthesis of other nanomaterials and the production of tailored functional nanomaterials and devices.     

Smart Approach for In Situ One‐Step Encapsulation and Controlled Delivery of a Chemotherapeutic Drug using Metal–Organic Framework–Drug Composites in Aqueous Media

Controlled release of an anticancer drug, doxorubicin (dox), from metal–organic framework (MOF)–drug composites is demonstrated under different external stimuli. 1,3,5‐Benzenetricarboxylic acid (H₃BTC) is used as an organic ligand, and iron acetate and zinc nitrate are used as metal sources to synthesize Fe–BTC and Zn–BTC MOFs, which are known to be biocompatible. The in situ formation of MOF–drug composites demonstrates high drug loading capacity compared to conventional methods. The present methodology is devoid of any extra steps for loading the drug after synthesis. Moreover, the drug loading is also independent of pore size of the MOF as the drug molecules are embedded inside the MOF during their in situ formation. The drug release was monitored under external stimuli including change to acidic pH and the presence of biocompatible liposomes for a period of more than 72 h. Steady‐state fluorescence spectroscopy is used to monitor the drug release as a function of time and confocal laser scanning microscopy is used to unravel the post‐release fate of doxorubicin in the presence of liposomes. It is found that drug release rate is higher for the Zn–BTC–dox composite than for the Fe–BTC–dox composite. This is attributed to the stronger binding between dox and Fe‐BTC than that between dox and Zn–BTC. This study highlights a novel approach for the preparation of MOF–drug composites in an aqueous medium for future biomedical applications.     

Ultrathin Graphdiyne Nanosheets Grown In Situ on Copper Nanowires and Their Performance as Lithium‐Ion Battery Anodes

A method is presented for the scalable preparation of high‐quality graphdiyne nanotubes and ultrathin graphdiyne nanosheets (average thickness: ca. 1.9 nm) using Cu nanowires as a catalyst. For the storage of Li⁺ ions, the graphdiyne nanostructures show a high capacity of 1388 mAh g^?1 and high rate performance (870 mA h g^?1 at 10 A g^?1, and 449.8 mA h g^?1 at 20 A g^?1) with robust stability, demonstrating outstanding overall potential for its applications.     

In Situ Observation of Successive Crystallizations and Metastable Intermediates in the Formation of Metal–Organic Frameworks

Understanding the driving forces controlling crystallization is essential for the efficient synthesis and design of new materials, particularly metal–organic frameworks (MOFs), where mild solvothermal synthesis often allows access to various phases from the same reagents. Using high‐energy in situ synchrotron X‐ray powder diffraction, we monitor the crystallization of lithium tartrate MOFs, observing the successive crystallization and dissolution of three competing phases in one reaction. By determining rate constants and activation energies, we fully quantify the reaction energy landscape, gaining important predictive power for the choice of reaction conditions. Different reaction rates are explained by the structural relationships between the products and the reactants; larger changes in conformation result in higher activation energies. The methods we demonstrate can easily be applied to other materials, opening the door to a greater understanding of crystallization in general.     

Pre‐targeted Imaging of Protease Activity through In Situ Assembly of Nanoparticles

The pre‐targeted imaging of enzyme activity has not been reported, likely owing to the lack of a mechanism to retain the injected substrate in the first step for subsequent labeling. Herein, we report the use of two bioorthogonal reactions—the condensation reaction of aromatic nitriles and aminothiols and the inverse‐electron demand Diels–Alder reaction between tetrazine and trans‐cyclooctene (TCO)—to develop a novel strategy for pre‐targeted imaging of the activity of proteases. The substrate probe ( TCO‐C‐SNAT4 ) can be selectively activated by an enzyme target (e.g. caspase‐3/7), which triggers macrocyclization and subsequent in situ self‐assembly into nanoaggregates retained at the target site. The tetrazine‐imaging tag conjugate labels TCO in the nanoaggregates to generate selective signal retention for imaging in vitro, in cells, and in mice. Owing to the decoupling of enzyme activation and imaging tag immobilization, TCO‐C‐SNAT4 can be repeatedly injected to generate and accumulate more TCO‐nanoaggregates for click labeling.     

Synthesis of Copper‐Substituted CoS2@CuxS Double‐Shelled Nanoboxes by Sequential Ion Exchange for Efficient Sodium Storage

The construction of hybrid architectures for electrode materials has been demonstrated as an efficient strategy to boost sodium‐storage properties because of the synergetic effect of each component. However, the fabrication of hybrid nanostructures with a rational structure and desired composition for effective sodium storage is still challenging. In this study, an integrated nanostructure composed of copper‐substituted CoS₂@Cu_xS double‐shelled nanoboxes (denoted as Cu‐CoS₂@Cu_xS DSNBs) was synthesized through a rational metal–organic framework (MOF)‐based templating strategy. The unique shell configuration and complex composition endow the Cu‐CoS₂@Cu_xS DSNBs with enhanced electrochemical performance in terms of superior rate capability and stable cyclability.