Yanan Niu

Elucidating structure–activity relationships in semiconductor photocatalysis has been significantly impeded by the inherent limitations of ensemble-averaged characterization techniques, which obscure the spatiotemporal heterogeneity intrinsic to catalytic surfaces. Single-molecule fluorescence microscopy (SMFM) surmounts this bottleneck by offering nanometer-scale spatial resolution coupled with the capacity to resolve single-turnover events. Herein, we provide a comprehensive overview of the State-of-the-Art applications of fluorogenic probe-coupled SMFM in deciphering the microscopic mechanisms governing photocatalysis. We begin by delineating the operational principles of total internal reflection fluorescence (TIRF) microscopy and categorizing the response mechanisms of three distinct classes of fluorogenic probes: oxidative (e.g., Amplex Red, APF), reductive (e.g., Resazurin, DN-BODIPY), and acidic (e.g., furfuryl alcohol, thiophene) reporters. Subsequently, we highlight seminal studies wherein SMFM has been leveraged to visualize facet-dependent charge separation on model photocatalysts—including TiO₂, BiOBr, and InSe—to map the dynamic activity associated with surface defects and to precisely locate active sites during photoelectrochemical water splitting. Finally, we critically assess the prevailing technical challenges, such as limitations in probe specificity and background interference, while offering a perspective on prospective avenues for methodological refinement. This review is intended to serve as a methodological cornerstone for advancing mechanistic understanding in photocatalysis and for guiding the rational design of high-performance catalysts.

Civil engineering infrastructure suffers material degradation, shortened service life and high maintenance costs under harsh environments and natural aging, threatening public safety. Nanopolymer composites, featuring designable microstructures and excellent macroscopic properties, provide a revolutionary solution to improve the weather resistance and toughness of civil engineering materials. This paper systematically clarifies the modification mechanisms of nanocomposites, focusing on nanofiller–polymer matrix interfacial interactions (physical adsorption, chemical bonding) and their synergistic effects in enhancing environmental aging resistance (UV, corrosion, freeze–thaw) and mechanical performance (toughening, strengthening, dynamic load resistance). It summarizes the latest applications in nanomodified protective coatings, sealing/bonding materials and composite structural components, revealing the inherent “structure-property-application” relationships. Furthermore, this paper addresses core large-scale application challenges, including technical bottlenecks, performance evaluation limitations and economic/environmental barriers. Finally, future research directions are proposed, covering multifunctional intelligent materials, green development, interdisciplinary computational methods and standardized systems. This review offers an integrated perspective, providing theoretical guidance and practical references for advancing durable, resilient and sustainable civil engineering.

Nanoparticles leverage their unique nanoscale effects to optimize concrete performance through synergistic multi-mechanism interactions. Core mechanisms include micro-filling effects (graded pore filling, optimized pore structure), nucleation (promoting crystallization of hydration products, refining microstructure), chemical reactivity (e.g., pozzolanic reaction of nano-SiO₂, enhancing interfacial transition zones), and interfacial strengthening (improving ITZ structure and stress transfer). Common nanomaterials (e.g., nano-SiO₂, Al₂O₃, carbon nanotubes) significantly enhance concrete’s mechanical properties, durability, and functionalities (e.g., self-sensing, electromagnetic shielding). However, nano-modified concrete still faces challenges such as poor dispersion, high cost, and environmental/health risks. Future efforts should focus on multi-scale mechanism research, green low-cost synthesis processes, and intelligent composite systems development to advance the engineering applications pf nano-modified concrete.

G-C₃N₄, a biocompatible material, has prominent applications in biology and is ideal for nano-enzyme studies. Though reported as a peroxidase mimic, its activity remains low. This group combined N,S-doped carbon quantum dots (NS-CQDs) with g-C₃N₄ (7NSC-g), verifying its peroxidase-like activity. Based on this, a ternary composite of Co₃O₄ in different forms and 7NSC-g was developed to enhance peroxidase activity, to design a g-C₃N₄-based composite enzyme. Characterizations determined the composition and morphology. Colorimetry evaluated peroxidase activity, where the simulated enzyme catalyzes blue product formation from the TMB substrate in the presence of H₂O₂. UV-Vis spectrophotometry measured absorbance changes to determine target concentrations. The results show Co₃O₄ doping improves catalytic activity, with larger specific surface area providing more activation sites. The highest activity of g-C₃N₄/NS-CQDs/Co₃O₄ was at 5% floral Co₃O₄, being efficient due to Co₃O₄’s electron-transfer acceleration and hydroxyl-radical mechanism. Under optimal conditions, the composite detected H₂O₂ (10.0–230.0 μM, detection limit of 0.031 μM) and glucose (10.0–650.0 μM, detection limit of 1.024 μM).

Zinc is an essential trace metal element in the human body, but it also constitutes a variety of proteins in the body of the important elements necessary; this element plays an important role in physiological metabolism. Disturbances in the metabolism of zinc ions in the body can significantly threaten human health, especially neurological diseases. Therefore, developing a rapid and straightforward method for determining zinc ions is important. Fluorescent probe technology has been widely used for detecting and labeling zinc ions. Among many fluorescent probes, the rhodamine derivative LPDQ fluorescent probe has unique application scenarios, for example, it plays an important role in the detection of zinc white in oil colors, and its advantages are simplicity, rapidity, and real-time operation. This paper introduces the types of fluorescent probes for zinc ions and the three main mechanisms of fluorescent probe detection. The characteristics, design strategies, and application effects of the three fluorescent probes for zinc ions, as well as their advantages and limitations, are reviewed and summarized, which are intended to provide valuable references for the development of new probes for zinc ions detection in the future and for the future direction of research in this field.

Throughout millions of years of biological evolution, shell structures have developed a highly complex layered organic–inorganic structure that makes them effective against a wide range of external impacts, including mechanical stress and chemical corrosion. Therefore, shell-like biomimetic materials are considered to possess high strength and toughness. Nevertheless, although shell structures have exhibited superior performance across multiple domains, understanding of their structural complexities and corrosion protection mechanisms remains relatively limited within the scope of human knowledge. In this study, alternating ZnO–graphene/epoxy coatings featuring shell-like structures were synthesized, and their anticorrosion properties were evaluated through the incorporation of ZnO to enhance the dispersion of graphene. Electrochemical impedance spectroscopy (EIS) tests showed that with an increased number of ZnO–graphene layers, the coating resistance of the bionic composite coating also increased: from 8.21 × 10⁷ Ω·cm² of the pure epoxy coating to 7.64 × 10⁸ Ω cm². The composite coating, comprising three alternating layers of zinc oxide and four layers of epoxy resin, exhibited an electrochemical impedance two orders of magnitude greater than that of pure epoxy resin following immersion in a 3.5% sodium chloride solution, demonstrating excellent corrosion resistance. The results showed that with increased ZnO–graphene layers, ZnO–graphene disperses more uniformly in water and has greater rigidity.