The three-dimensional (3D) imaging of structural and compositional features at the nanometer and atomic scale is crucial for advancing the applications of nanomaterials in energy storage and catalysis. Transmission electron microscopy, particularly in scanning mode, has traditionally provided atomic-resolution structural insights. However, achieving high-resolution 3D compositional imaging of beam-sensitive materials remains formidably challenging due to the limitation of electron dose. Recent innovations in hardware and computational methods, such as data-fusing and deep learning, have enabled 3D compositional imaging at the sub-nanometer scale with significantly reduced electron doses. This review highlights the principles, advancements, and applications of electron tomography and associated techniques for 3D compositional imaging, summarizes state-of-the-art progress achieved by multimodal tomography and model-free reconstructions, and underscores the transformative potential of these developments for 3D high-resolution characterizations of beam-sensitive materials.

Detection of small molecular metabolites in the body can reflect the overall health status of the human body, being essential for understanding metabolism and diagnosing diseases. For the detection and monitoring of small molecular metabolites in complicated biological systems, the sensitive detections of trace metabolites and their pathways have been pursued by different strategies. Mass spectrometry provides high sensitivity and specificity for metabolic studies, while commercial techniques normally require sample pretreatments to limit the multiple examining requirements. Fortunately, ambient mass spectrometry (AMS) can meet rapid clinical examinations due to its rapid and direct detection of biological molecules without or with fewer sample pretreatments. By virtue of AMS, the real-time and online monitoring of small molecular metabolites can be achieved for examining metabolism mechanisms and facilitating targeted interventions. This review summarizes the application of AMS in the monitoring of small molecular metabolites, including glucose, lipids, amino acids, nucleotides, and aldehydes, as well as examinations of reaction mechanisms in clinical applications. This would provide insights on constructing powerful diagnostic tools for clinical applications.

Zeolites are a class of inorganic microporous crystalline materials with ordered pore channels, unique shape selectivity, adjustable acidity and alkalinity, and high stability and have been widely used in gas adsorption and heterogeneous catalysis. The size of the zeolite pore structure determines its molecular sieving properties. Therefore, flexibly adjusting the zeolite pore structure and the host-guest interactions with guest molecules to control diffusion or reaction pathways is crucial for designing novel zeolites. Observing the real movement behavior of small molecules and changes in the local structure of the zeolite framework at the micro-nano scale is of great significance. Recently, emerging scanning transmission electron microscopy (STEM) imaging techniques, such as integrated differential phase contrast/optimum bright-field STEM (iDPC/OBF-STEM) and 4D-STEM ptychography have shown great potential for atomic resolution characterization of zeolites, since these are greatly advantageous for imaging electron beam-sensitive materials and light elements. This review first introduces the structural characteristics and applications of zeolites. Secondly, we discuss the application of three emerging imaging techniques in atomic imaging of zeolites. Thirdly, we focus on using iDPC-STEM imaging technology to observe the host-guest interactions between zeolites and single molecules (e.g., benzene, p-xylene, and pyridine). Furthermore, we explore the adsorption-desorption behavior of single molecules in zeolites using in situ iDPC-STEM imaging technology. Finally, we discuss the current challenges and future prospects of advanced TEM characterization techniques in the imaging of zeolite-confined single molecule.

Native proteins refer to proteins that exist in their natural state, have a correctly folded three-dimensional structure, and have biological functions. Characterization of protein higher-order structure and protein-protein interactions is crucial for a deeper understanding of protein structure and function, as well as drug development. Native mass spectrometry (nMS) can provide key information about the intact mass, subunit composition, stoichiometry, and post-translational modification sites of protein complexes or individual proteins. However, when directly analyzing complex mixtures, the resolution of nMS is reduced, and it becomes difficult to detect low-abundance proteins. Therefore, sample separation and purification play an important role in nMS studies of proteins. In this review, we describe the mainstream native separation methods coupled to mass spectrometry, including liquid chromatography and capillary electrophoresis, and discuss the challenges encountered when these technologies are combined with mass spectrometry and the latest advances in the characterization of native proteins. The article provides a comprehensive overview of non-denaturing separation methods, including practical application issues, such as buffer selection, flow rate control, and interface technology. At the same time, potential native separation technologies, such as gradient focusing and freeflow electrophoresis that have not been widely used in nMS are also introduced, providing new perspectives for high-resolution detection of complex samples and detection of low-abundance proteins.

Nanomaterials have greatly received interest in various fields due to their excellent activity, typically attributed to their nanoscale physical and chemical properties. Transmission electron microscopy (TEM) as a powerful tool for characterizing nanomaterials can offer microscopic information with high spatial resolution. However, TEM faces challenges in obtaining information along the electron beam direction (Z direction), which limits its ability to explore the unique characteristics of nanomaterials on a three-dimensional (3D) scale. Electron tomography (ET) is an advanced imaging technique that allows for the visualization of 3D structures of nanomaterials. When combined with energy-dispersive X-ray spectroscopy (EDS) or electron energy loss spectroscopy (EELS), it enables researchers to reveal chemical changes in three dimensions, enhancing the understanding of the complex mechanisms underlying changes in chemical properties. This review summarizes and discusses the recent advancements in EDS/EELS (chemical-sensitive) ET imaging techniques, including the traditional reconstruction method, deep learning-based method, and multi-modal method, which provide detailed processes of reconstruction to facilitate the understanding of how they work for related researchers. Moreover, several successful applications are presented to show the capabilities of chemical-sensitive ET in diverse fields. Finally, the existing challenges and solutions are discussed to propel the development of ET imaging techniques.

Photocatalysis is a promising approach for solar energy conversion and environmental remediation, which has garnered increasing attention. Advanced in situ characterization techniques enable real-time observation of dynamic changes in catalyst structure, charge transfer, and surface species during photocatalytic reactions, which is crucial for understanding the relationship between photocatalyst structure and activity. This review summarizes the main applications of in situ characterization techniques in photocatalysis, discusses their contributions to optimizing photocatalyst performance for enhanced solar energy conversion and environmental applications, provides guidance for designing in situ experiments to understand catalytic mechanisms, and presents an outlook on the future development of in situ characterization techniques in photocatalysis.

Mass spectrometry (MS) is widely used in medical applications, such as pharmacokinetics, drug discovery, and clinical diagnostics, as it enables medical researchers and practitioners to gain insights into pathogenic mechanisms, identify biomarkers for diagnosis and monitoring, and develop new treatments. Mass spectrometry imaging (MSI) is a powerful analytical technique that combines the spatial information from imaging with the chemical information from MS. MSI assists medical researchers in various ways, including biomarker discovery, drug development and evaluation, personalized medicine, tissue imaging, and histochemical analysis. In addition, MSI not only provides high-resolution images of sample structures and enables researchers to identify specific cell types and their functions, but also enables the simultaneous visualization of multiple biomolecules within a single cell and allows researchers to study complex biological processes with greater precision. In this review, we summarize recent advances in MSI for single cells and cellular-level analysis and discuss how this technology can be used to improve our understanding of diseases and develop new treatments. The potential challenges and limitations of MSI in single-cell analysis, as well as prospects in this field, are also highlighted.

Nanoscale multi-principal element metal (MPEM) offers a diverse and adjustable compositional range of active, holding promise for applications in water oxidation. Nevertheless, the synthesis of MPEM nanoparticles poses challenges owing to the tendency of particles to experience growth, aggregation, or phase separation during annealing processes. Here, we introduce a rapid heating and cooling method that enables the fabrication of rare earthcontaining MPEM through instantaneous heating and rapid cooling processes. The TEM results indicate that the metal particles are roughly around 120 nm in size, with uniform distribution of various metal elements on the particles. The X-ray characterizations further reveal that the metal catalyst exhibits predominantly a face-centered cubic (FCC) structure with partial oxidation on the surface. Notably, the obtained MPEM catalysts exhibit a current density of 10 mA/cm² with an overpotential of 244 mV, which is 26 and 104 mV lower than the overpotentials of FeCoNiCr and commercial RuO₂. Moreover, the MPEM catalyst can operate stably for over 200 h at current densities of 10 and 100 mA/cm².

Electrocatalytic reduction reaction of carbon dioxide (CO₂RR) to formic acid is widely considered an effective strategy for addressing the greenhouse effect and enhancing energy conversion efficiency. However, existing catalytic systems are severely hampered by insufficient activity and significant hydrogen evolution reaction (HER), which substantially compromises the selectivity and stability of CO₂RR, necessitating the development of highly efficient and stable electrocatalysts. Herein, we present a heteroatomic modification strategy to synthesize B-doped Bi and N-doped Bi electrocatalysts, and systematically investigate the regulation mechanism of incorporated elements on the electronic environment using X-ray absorption fine structure (XAFS) spectroscopy and other characterization techniques. The optimized B-doped Bi catalyst demonstrates exceptional catalytic performance, achieving a remarkable Faradaic efficiency of 95% for formic acid production at a high current density of −190 mA/cm² under alkaline conditions, while maintaining excellent stability for 20 h. Through comprehensive experimental characterization and theoretical calculations, we reveal that the B-doping-induced electron-rich structure significantly promotes CO₂ molecule activation and facilitates the formation of the key intermediate ^*OCHO, thereby achieving high selectivity and stability in CO₂RR. This work not only elucidates the crucial role of electronic environment in CO₂ electrocatalytic conversion but also provides innovative insights into the rational design of high-performance electrocatalysts.

Single-atom catalysts (SACs) have shown great potential in catalysis and energy-related applications. Among these, iron SACs stand out for their exceptional performance and environmental friendliness. In this study, we investigated the transformation of iron oxide nanoparticles into iron single atoms, exemplifying a top-down synthesis strategy. Using in-situ transmission electron microscopy (TEM), we directly observed the dynamic behaviors during the pyrolysis-induced atomization of Fe₃O₄ nanoparticles along the [110], [111], and [112] zone axes at atomic-scale resolution. Reducing gases were supposed to release during the thermal pyrolysis of an organic reducing agent and facilitate the generation of Fe single atoms. The rate-limiting step was the reaction of these gases with atoms at surface steps and vertices of Fe₃O₄ nanoparticles. Electron energy loss spectroscopy revealed a reduction in the Fe valence state and a transition in the Fe-O coordination environment after in-situ thermal treatment. The high-density dispersion of Fe single atoms was facilitated by the weak repulsive interactions between Fe atoms. This study enriches the understanding of the gas-assisted atomization mechanism and offers valuable insights for optimizing the production of high-density SACs. The methodology and findings can be extended to other material systems, broadening the scope of single-atom engineering and catalysis applications.

RNA molecules undergo a variety of modifications, including inosine modification, also called adenosine-to-inosine (A-to-I) RNA editing, which is prevalent across all domains of life. To unravel the roles of A-to-I RNA editing, it is essential to accurately quantify inosine in RNA at specific sites. Here, we developed a ligation-assisted qPCR (LA-PCR) method for the quantitative and site-specific analysis of A-to-I RNA editing. In LA-PCR, adenosine on an edit site pairs with thymidine. In contrast, inosine fails to pair with thymidine, disrupting the nick ligation of the two DNA probes located upstream and downstream from the editing site. The reduction in the liaged products can be quantified through subsequent qPCR, thus enabling the quantification of the A-to-I RNA editing level. The LA-PCR approach was successfully employed to detect and quantify the A-to-I RNA editing at position 2814 in Ino80dos RNA from mouse tissues. A notable elevation in A-to-I RNA editing levels was found across various tissues from sleep-deprived mice in comparison to control mice, suggesting a potential association between A-to-I RNA editing and sleep behavior. The proposed method facilitates the quantitative analysis of A-to-I RNA editing at specific sites, aiding in the elucidation of the functions and mechanisms of A-to-I RNA editing.

Sodium-ion conducting materials in sodium-ion battery have drawn widespread attention in energy storage technologies due to the advantages of low cost, high performance, and efficient environmental adaptability. Herein, bond valence site energy (BVSE) calculations were used to predict the sodium ion electrical performances by the Na nonstoichiometric modifications, and we have carried out fine experiments to modulate the sodium ion conductivity of Na_xZn₂TeO₆ guided by BVSE calculations. The optimized composition Na_2.1Zn₂TeO₆ shows the superior sodium ionic conductivity of 5.3×10^-3 S/cm at 190 ℃, with a low activation energy of 0.28 eV. The excess Na preferentially occupies the Na1 site with tetrahedral voids, which has a higher capacity for sodium ion migration, as revealed by the combined neutron powder diffraction technique with the 1D and 2D ²³Na solid-state NMR technique, which is responsible for the variations in sodium ion conductivity. In addition, it is worth noting that the resulting Na_2.1Zn₂TeO₆ material maintains superior thermal and phase stability, as well as approximately the same thermal expansion coefficient values even during the temperature rise and fall cycles in the temperature range of 25—800 ℃. Furthermore, molecular dynamics simulations revealed that the sodium ions exhibit long-range anisotropic migration within the Na⁺ interlayers of Na_2.1Zn₂TeO₆.

Hyperpolarized ¹²⁹Xe magnetic resonance imaging (MRI) is a powerful tool for detecting respiratory system diseases. However, ¹²⁹Xe is an inert gas and lacks specific detection capability. Entrapping xenon within molecular cages to enable specific detection is a challenging task, and numerous molecular cages have been developed and evaluated to address this challenge. Herein, we report that the aluminum-based metal-organic framework, CAU-1, can effectively entrap xenon for hyperpolarized ¹²⁹Xe MRI in aqueous solutions. This platform exhibits high water stability and good dispersibility, and shows excellent xenon entrapment capability, even at a concentration as low as 50 μg/mL. Importantly, it is responsive to pH changes across a range from 6.6 to 5.0, making it promising for monitoring the weakly acidic environment in tumors or metabolic abnormality. Furthermore, the scalable and cost-effective production of this molecular cage will facilitate future advancements in molecular imaging and chemical sensing applications.

In order to expand the range of synchrotron radiation structural characterization modes, an automated in-situ X-ray absorption fine structure (XAFS) spectroscopy characterization for electrochemical research has been established. An in-situ control system equipped with an automatic trigger capability facilitates automated acquisition of XAFS and electrochemical data. Furthermore, the quick scanning XAFS (QXAFS) terminal, in-situ server and data storage were all controlled by remote users, enabling remote measurement to be achieved. Using this system, the evolution of the local structure near Fe atoms during the charging and discharging of lithium-sulfur battery (LSB) cathode materials was observed, which provides deep insights into the sulfur reaction pathway in LSBs by leveraging structural information. The system established here paves the way for fully automated and intelligent in-situ XAFS experiments.

An in-situ double-tilt holder has been made to integrate laser illumination and fluorescence-based spectroscopic analysis for conducting liquid-phase electron microscopy (LP-TEM) experiments using ordinary TEM. The setup differs from the existing geometry. Laser illumination and the collection of fluorescence signals were achieved using a single optical fiber, with efficiency optimized by adjusting the fiber position and grid tilt angle. Fluorescence emission of common organic dyes, propidium iodide (PI) and cyanine dyes, and Förster resonance energy transfer (FRET) signals of a FRET pair, Cy3/Cy5, were obtained from three types of liquid cells, including carbon film, graphene, and nanopipette liquid cells. The successful application of FRET-LPTEM enables LP-TEM experiments to be equipped with controlled light-triggering capability, detection of fluorogenic small molecules during chemical reactions, and the standard FRET experiments for macromolecules being conducted with LP-TEM. FRET-LPTEM presents opportunities for unraveling pathways underpinning the synthesis and assembly of optically active organic and biological materials.

Molecular motions in metal-organic frameworks (MOFs) play important roles in guest diffusion processes, which is crucial for gas capture and separations. Three-dimensional electron diffraction (3DED) has emerged as an advanced method to probe molecular motions, such as linker librations. For a study of molecular motions by 3DED, data quality is the key to the analysis and interpretation. Herein, we present a systematic work to investigate the effects of data completeness, resolution, and signal-to-noise ratio on the identification of molecular motion in MIL-140C. We determine the limits of completeness and resolution required for reliably analyzing molecular motions. In addition, data processing can affect the signal-to-noise ratio of data, and we demonstrate their influence on probing molecular motions. This work provides reference conditions on 3DED data quality to obtain reliable information on molecular motions.

Ultra-high nickel layered cathodes (Ni≥95%) have emerged as prospective candidates for next-generation lithium-ion batteries (LIBs) due to their exceptional specific capacity and costeffectiveness. However, the commercial application of these cathodes has been hindered by several challenges, including structural instability during cycling, high sensitivity to air, and slow Li⁺ migration. In this research, a one-step modification strategy was developed to simultaneously achieve Mg doping and Li₃PO₄ layer coating for the ultra-high nickel cathodes. Characterization results demonstrated that Mg doping not only alleviates lattice strain changes during the H2-H3 phase transition (H2: the second hexagonal phase; H3: the third hexagonal phase) but also serves as a structural anchor, preventing Ni²⁺ migration and occupation within the Li layer. The Li₃PO₄ surface coating layer acts as an electrochemical shield, protecting against interfacial side reactions and enhancing the Li+ diffusion rate. As a result, the LiNi_0.95Mn_0.05O₂ cathode, with both internal and external modifications, demonstrates significant improvement in cycling stability (85.7% capacity retention after 100 cycles) and Li⁺ transport performance (130.6 mA·h·g^-1 at 10 C, 1 C=189.6 mA·h·g^-1), providing a solid foundation for the further development and application of ultra-high nickel cathodes.

High-angle annular dark-field scanning TEM (HAADF-STEM) images play a critical role in the structural characterization of chemical materials. However, drift correction is a critical challenge in imaging beam-sensitive materials, where sample motion and signal-to-noise ratio (SNR) hinder high-resolution image reconstruction. In this study, we propose an enhanced Bragg filter (EBF) method for robust drift correction and high-resolution reconstruction of HAADF-STEM images. The EBF method involves the semi-manual selection of reflection spots to extract periodic lattice features, which significantly enhance the SNR and preserve periodicity in low-dose images. We demonstrate the superior performance of the method by comparing it with conventional low-pass and band-pass filters. The effectiveness of the EBF method is validated on ZSM-5 zeolite crystals, achieving a spatial resolution of 1.25 Å (1 Å=0.1 nm) and enabling precise tracking of structural evolution under electron beam exposure. Furthermore, we apply the EBF method for super-resolution imaging of ZSM-5 at low magnification, enriching structural details without compromising the field of view. This study presents a robust solution for imaging beam-sensitive materials and advancing low-dose electron microscopy techniques.

BiVO₄ (BVO) is widely utilized in photothermal catalysis because of its favorable bandgap structure (2.4 eV), excellent photo response capabilities and high thermal stability. However, the mechanism of BVO photothermal corrosion still remains unclear due to the lack of visualized characterization on the degradation process in real time. Herein, we directly unveil the photothermal-induced microstructural evolution of BVO through in-situ heating (scanning) transmission electron microscopy [(S)TEM]. The results indicate that the electrons are the initiating condition (“switch”) for the photothermal corrosion of BVO, resulting in the precipitation of Bi and reduction of V⁵⁺ to V³⁺ in the substrate, while the thermal field facilitates the evaporation of Bi and the recrystallization of V₂O₃. This work sheds light on the mechanism of BVO photothermal corrosion in dynamics and provides significant insights into the photothermal synergistic effects.

The study of the metabolic toxicity of perfluorooctanoic acid (PFOA) is of great importance in assessing its potential impact on aquatic organisms and the aquatic environment, and provides a fundamental scientific basis for environmental protection and sustainable development. In this study, an electrospray ionization (ESI) source capable of direct analysis of solution samples was combined with a high-resolution Orbitrap Fusion Tribrid mass spectrometer to investigate the metabolic perturbations induced by different concentrations of perfluorooctanoic acid (PFOA) and their correlations in skin mucus and liver tissue of tilapia. Seven common metabolites were found in mucus and liver, and nitrogen metabolism pathways were disturbed in all of them. The upregulation of glutamate in mucus may reflect an increased demand for amino acids and energy, whereas the down-regulation of glutamate in the liver may lead to dysregulation of nitrogen metabolism, protein synthesis and amino acid metabolism. Enrichment analyses suggest a dysregulation of nitrogen metabolism pathways, which may lead to impaired maintenance of tissue function and dysregulated energy metabolism in tilapia.