Ferromagnetic Ni1-xVxO1-y Nano-Clusters for NO Detection at Room Temperature: A Case of Magnetic Field-Induced Chemiresistive Sensing

Mesoporous Boron Subphosphide: Intrinsic Electron Deficiency Enabling Selective Low-ppm of Chemiresistive CO Detection in Harsh Environments

Carbon monoxide (CO) is infamous for its hazardous effects, mainly because it displaces oxygen in the bloodstream. Its danger is amplified by its odorless and colorless nature, making it difficult to detect. Exposure to even low concentrations of CO (≤50 ppm) is considered harmful to human health. Common sources of CO, such as fossil fuel-powered vehicles and machinery, primarily operate under harsh high-temperature conditions. Currently, available low-ppm of CO sensors struggle in these environments typical of CO emitters, highlighting the urgent need for advanced sensors capable of reliable operation in such conditions. In this study, nanocrystalline mesoporous icosahedral boron subphosphide is synthesized via a solid-state technique and evaluated for its CO sensing capabilities. The material exhibits selective detection of low ppm of CO at temperatures exceeding 500 °C, demonstrating a significant sensing response of ∼4 toward 50 ppm of CO at 600 °C. Electronic and structural analyses attribute boron subphosphide's chemiresistive behavior to its electron-deficient nature, which is crucial for effective CO interaction. Additionally, the sensitivity of boron subphosphide to CO can be modulated under external magnetic fields, underscoring its potential for adaptable sensing applications. This work introduces boron subphosphide as a promising candidate for CO sensing in harsh conditions and provides fundamental insights into its sensing mechanism driven by intrinsic electron deficiency. The findings offer a pathway for the development of advanced sensors capable of reliably detecting low concentrations of CO in harsh environments where precise monitoring is critical to public health and safety.

Magnetic Field Assisted Enhanced Sensitivity of Nonferromagnetic Materials Boosting the Carrier Transfer: Mechanistic Studies

The performance of semiconductor sensors is determined by reaction kinetics, conductivity, and electron mobility, which are undoubtedly closely related to the electron motion behavior. Therefore, the effective regulation of electronic states is crucial for improving gas sensing properties. Previous methods of enhancing the gas-sensing performance have induced complex material modifications, and the extent of performance improvement is usually very limited. Further optimization of the gas sensing performance requires continuous efforts to advance new technologies. Toward this issue, a novel magnetic field-induced strategy is adopted to boost the carrier transfer efficiency of nonferromagnetic semiconductors. The gas sensing investigation results manifest that the applied magnetic field can effectively enhance the sensitivity and reduce the baseline resistance. The In2O3 NC-2 (In2O3 nanocubes) with an applied magnetic field have a greatly enhanced response of 161.4 toward 100 ppm formaldehyde, which is 2.5 times higher than that without magnetic field. The enhanced gas sensing properties can be mainly attributed to magnetization of reactive materials, which makes the orientation of electronic magnetic moments consistent, thus greatly contributing to reactivity. This work introduces a practical approach to effectively improve gas sensing performance without further morphology optimization, noble metal catalysis, structural modification, and material cladding. The results of this study provide new insights for designing novel gas sensors to improve the gas sensing performance.

Multi-Functional Applications of H-Glass Embedded with Stable Plasmonic Gold Nanoislands

Metal nanoparticles (MNPs) are synthesized using various techniques on diverse substrates that significantly impact their properties. However, among the substrate materials investigated, the major challenge is the stability of MNPs due to their poor adhesion to the substrate. Herein, it is demonstrated how a newly developed H-glass can concurrently stabilize plasmonic gold nanoislands (GNIs) and offer multifunctional applications. The GNIs on the H-glass are synthesized using a simple yet, robust thermal dewetting process. The H-glass embedded with GNIs demonstrates versatility in its applications, such as i) acting as a room temperature chemiresistive gas sensor (70% response for NO2 gas); ii) serving as substrates for surface-enhanced Raman spectroscopy for the identifications of Nile blue (dye) and picric acid (explosive) analytes down to nanomolar concentrations with enhancement factors of 4.8 × 106 and 6.1 × 105 , respectively; and iii) functioning as a nonlinear optical saturable absorber with a saturation intensity of 18.36 × 1015 W m-2 at 600 nm, and the performance characteristics are on par with those of materials reported in the existing literature. This work establishes a facile strategy to develop advanced materials by depositing metal nanoislands on glass for various functional applications.