Hydrogen peroxide (H₂O₂) is widely used but highly toxic at elevated concentrations, necessitating ultrasensitive detection for safety and diagnostics. Current peroxidase nanozyme approaches for H₂O₂ detection and kinetic analysis are limited to ensemble measurements, where collective signals mask single-particle heterogeneity, compromise sensitivity, and preclude precise structure-activity correlations. To address this limitation, we herein employ Fe₃O₄@Fe/C as a model single-particle nanozyme and implement single-molecule fluorescence imaging to monitor, in situ, the catalytic oxidation of a non-fluorescent substrate to a highly fluorescent product by H₂O₂ at the single-particle level, thereby constructing an ultrasensitive H₂O₂ detection platform. Through correlating kinetic parameters with H₂O₂ response, we demonstrate that the single-particle assay achieves a limit of detection (LOD) of 24.17 nM with a linear range of 0.2-3 μM, representing a ~58-fold improvement in sensitivity over solution phase ensemble measurements (LOD=1.39 μM). In addition, quantitative analysis of the kinetic parameters reveals pronounced catalytic non-uniformity among individual nanozyme particles. This quantitative analysis system at the single-particle level provides a new method for ultrasensitive detection, and further offers new insights into revealing the microscopic processes of the detection reaction and guiding the study of structure-activity relationships.

Infrared photodetectors play an essential role in diverse military and civilian applications. Nevertheless, traditional infrared detection materials often suffer from inherent limitations, such as fixed bandgaps and stringent low-temperature operational requirements. The emergence of two-dimensional (2D) materials has revolutionized infrared detection technology, enabling the development of efficient room-temperature photodetectors. Among various 2D materials, black phosphorus (BP) has attracted considerable attention due to its narrow direct bandgap, tunable electronic properties, and exceptional hole mobility. These unique attributes endow BP-based infrared photodetectors with superior performance, including ultrafast response times, broad detection spectral ranges, and remarkably low dark currents. This review systematically summarizes recent advancements in material synthesis techniques, underlying device principles, and performance optimization strategies of BP infrared photodetectors. Additionally, it critically addresses ongoing challenges and offers a comprehensive perspective, laying a solid theoretical foundation and practical roadmap for advancing next-generation high-performance infrared photodetection technologies.

The widespread proliferation of modern wireless devices coupled with overlapping power emissions has brought about electromagnetic (EM) pollution issues, posing many challenges to environment and human health. Therefore, the development of EM shielding devices with high green shielding index (g_s) is essential, as they offer absorption-dominant protection that minimizes reflections and safeguards both health and electronics. MXene, with its intrinsic ultra-high electrical conductivity, liquid-phase tunable surface chemistry, low density, large specific surface area, thermal stability, and mechanical stability, has become the leading two-dimensional (2D) material driving the development of green EM shielding devices. In this review we emphasize device-level strategies with engineered architectures for MXene-based green EM shielding. We first examine MXene’s crystal and electronic structure and the fundamental attenuation mechanisms in MXene-based devices. Then we survey fabrication and assembly methods, analyzing three device-level strategies for MXene-based green EM shielded devices: 3D architectures, meta-structure/meta-surfaces, and external stimulus. Throughout, we highlight how MXene’s distinguished properties enable green EM interference (EMI) shielding devices that minimize secondary interference. Finally, we discuss the challenges faced in the effective utilization of MXene-based in green EM shielding devices, provide insights into these challenges, and offer guidelines for developing the solutions of next-generation green MXene-based EM shielding devices.