ABSTRACT The electromagnetic interference shielding effectiveness (EMI SE) of materials is highly related to their microstructures. Mimicking nature is an effective and useful strategy for designing high performance materials, even though it remains a great challenge. Herein, a biomimetic, anisotropic, robust wood‐derived 3D conductive Bio‐C@YB 2 C 2 framework was synthesized by in situ boron/carbon thermal reduction reaction on the carbonized wood template. The as‐obtained Bio‐C@YB 2 C 2 composites accurately inherit the specific microstructure of natural wood, providing pathways for terahertz wave dissipation. The thermal and electrical conductivity of composites increased with the content of layered superconductor YB 2 C 2 coated on the surface of Bio‐C. The resulting Bio‐C@30YB 2 C 2 ceramic exhibits exceptional performance, including a high thermal conductivity of 12.36 W·m −1 ·K −1 , an outstanding electrical conductivity of 204.13 S·cm −1 , and an efficient Joule heating performance, reaching 173.3°C at an applied voltage of 1.5 V. Meanwhile, it demonstrated a remarkable EMI SE (55.5 dB) in the X‐band (8.2–12.4 GHz) for the sample with 1.5 mm thickness and normalized EMI SE/ t value as high as 37.0 dB·mm −1 , surpassing numerous other EMI shielding materials and their composites at equivalent thicknesses. It was due to the multiple reflections in the vertically aligned and densely interconnected microchannels, conduction loss and interfacial polarization at the interface of Bio‐C@30YB 2 C 2 , and the superconductivity of YB 2 C 2 . This approach is anticipated to provide novel insights for designing ultra‐high temperature electromagnetic shielding and electric heating materials.
ABSTRACT Reduced graphene oxide (rGO)‐based microwave absorbers generally exhibit strong dielectric attenuation but unsatisfactory impedance matching, while simply increasing the magnetic‐component loading does not necessarily improve microwave absorption. Herein, Ni nanoparticle‐decorated rGO hybrids were prepared through coprecipitation followed by chemical vapor deposition‐assisted thermal reduction. A dual‐comparison framework combining Ni‐loading‐state regulation and same‐precursor NiO‐to‐Ni phase evolution was employed to clarify the relationships among nanoparticle dispersion, phase composition, electromagnetic response, and microwave absorption performance. Increasing the initial Ni precursor concentration increased the mean Ni nanoparticle size from 23.25 to 25.48 and 29.98 nm and promoted more pronounced aggregation, whereas the absorption performance exhibited a nonmonotonic dependence on the nominal Ni loading. For the optimized rGO/Ni‐5 hybrid, the Ni content was estimated to be approximately 32.6 wt.% by thermogravimetric analysis and 30.36 wt.% by semi‐quantitative energy‐dispersive X‐ray spectroscopy analysis. At a filler loading of 15 wt.%, rGO/Ni‐5 achieved a minimum reflection loss of −35.5 dB at 8.4 GHz with a thickness of 3.0 mm and an effective absorption bandwidth of 3.28 GHz from 9.52 to 12.80 GHz at 2.3 mm. Vibrating sample magnetometer measurements showed that rGO/Ni‐5 exhibited the strongest static magnetic response among the investigated rGO/Ni hybrids, while radar cross‐section simulations demonstrated reduced electromagnetic scattering compared with pure rGO and the rGO/NiO‐5 phase control. These results indicate that the superior performance of rGO/Ni‐5 originates from the coordinated regulation of nanoparticle dispersion, phase composition, dielectric–magnetic response, impedance matching, and attenuation capability, rather than from simply maximizing Ni loading or any individual loss parameter.
ABSTRACT ZnO nanowires grown by chemical bath deposition have emerged as versatile building blocks for a wide range of functional devices, thanks to their unique electronic, optical, and piezoelectric properties. However, despite its relative simplicity to control the structural morphology and properties of ZnO nanowires, achieving precise control over their doping remains a significant challenge, while being highly critical to meet the requirements of the targeted functional devices. The present review provides a comprehensive analysis of the state‐of‐the‐art and scientific challenges associated with the residual and intentional doping processes of ZnO nanowires, including the role of native point defects, hydrogen‐related defects, and extrinsic dopants. The intentional incorporation processes of shallow donors (e.g., Al, Ga, In, Cl) and deep acceptors (e.g., Cu, Sb) are discussed in detail, along with the effects of transition metals (e.g., Cr, Co, Mn, Ni) and rare earth elements (e.g., Ce, Sm, Eu, Tb) on the structural and optoelectronic properties of ZnO nanowires. Additionally, the review highlights the background and latest advancements in ZnO nanowire‐based functional devices in the fields of electronics, optoelectronics, photovoltaics, piezoelectricity, photocatalysis, and chemical/biological sensing. The interplay between doping strategies and device performance is eventually emphasized, offering careful insights into the optimization of ZnO nanowires for next‐generation technologies.
ABSTRACT Public health emergencies and the escalating burden of chronic diseases necessitate a paradigm shift from centralized laboratory testing to rapid, decentralized, and point‐of‐care (POC) diagnostics. Optical nanobiosensors have emerged as transformative tools, exhibiting high sensitivity, label‐free detection, and real‐time monitoring efficacies essential for addressing biomedical complexities. In this review, we critically examined the evolution of optical POC nanobiosensors from fundamental nanomaterial engineering to trans‐scale autonomous bio‐integrated systems. We discussed the physicochemical engineering of advanced nanomaterials, such as plasmonic nanomaterials, quantum dots, metal–organic frameworks, and 2D materials like MXenes, which considerably improved signal amplification and detection limits. It is attributed to the ability of nanomaterials to modulate light–matter interaction at the nanoscale using various physics principles such as fluorescence, photonics, plasmonic, fiber optics, interferometry, and spectrometry. Furthermore, we critically examined the convergence of nanophotonics with microfluidics, artificial intelligence, and 5G‐supported Internet of Medical Things to develop smart and data‐driven diagnostics. Innovative POC modules are explored, ranging from lab‐on‐chip and hospital‐on‐chip platforms to wearable, skin‐embedded, and tattoo‐based biosensors capable of continuous physiological monitoring. Besides, we address translational challenges related to scalability and biocompatibility, providing sustainable frameworks using green nanotechnology and self‐powered triboelectric technologies to reduce ecological footprints. Future advancements depend on interdisciplinary collaboration to bridge the gap between laboratory innovations and clinical implementation. It will pave the way for sustainable, POC, and smart global healthcare solutions, raising an era of sensor intelligence.
ABSTRACT Nickel‐based catalysts hold significant promise for efficient hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) due to their dynamic reconstruction capability. However, uncontrolled reconstruction promotes lattice oxygen participation, triggering the destructive lattice oxygen‐mediated mechanism (LOM) that causes rapid catalyst disintegration at industrial current densities. Herein, we resolve the challenge through Fe doping‐enabled selective adsorbate evolution mechanism (AEM) pathway engineering in a Ni 2 P/NiMoO 4 heterostructure (Fe‐Ni 2 P/NiMoO 4 ). During OER, Fe doping triggers deep reconstruction into Ni(Fe)OOH while suppressing the LOM via electronic modulation, yielding an AEM with optimized OH* adsorption. This mechanism‐selective design delivers exceptional bifunctional performance: 140 mV (HER) and 256 mV (OER) overpotentials at 100 mA cm −2 , sustained stability at 200 mA cm −2 for 100 h (HER and OER) and 50 mA cm −2 for 100 h (overall water splitting). Mechanistic studies reveal Fe doping's dual role: (i) accelerating reconstruction kinetics to form Ni(Fe)OOH as the AEM‐active phase and (ii) stabilizing the Fe‐Ni 2 P conductive backbone by eliminating oxygen‐loss pathways. This work pioneers mechanism‐selective reconstruction as a design principle for industrial electrocatalysts, moving beyond empirical activity optimization toward rational pathway control.
