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Flower-like In(OH) 3 was synthesized by a facile homogeneous precipitation method and subsequently calcined at 300 °C to prepare nanosheets assembled 3D flower-like mesoporous In 2 O 3 , which was then modified with Au nanoparticles via sol-immobilization method to produce 3D hierarchical mesoporous Au/In 2 O 3 for ethanol detection. The as-prepared Au/In 2 O 3 were carefully characterized by XRD, SEM, HRTEM and XPS techniques. The flower-like structure was assembled by many ultrathin coarse mesoporous In 2 O 3 nanosheets, and Au nanoparticles with an average size of 3.3 nm were evenly dispersed on In 2 O 3 nanosheets. The 3D flower-like mesoporous 1%Au/In 2 O 3 has a high specific surface area of about 130 m2 g−1 and shows the best sensitivity to ethanol among the flower-like mesoporous Au/In 2 O 3 materials. It can sensitively detect ethanol gas at a relatively low temperature of 160 °C with a response of 115–50 ppm ethanol, increased by nearly 11 times compared to In 2 O 3 at 210 °C. The 3D flower-like mesoporous 1%Au/In 2 O 3 also has good selectivity to ethanol with response about 9.4, 26.1, 20.9 and 29.5 times higher than that to acetone, methanol, toluene and xylene, and it displays excellent linear relationship between the response and the ethanol concentration. The markedly improved sensitivity and selectivity of the 3D flower-like mesoporous 1%Au/In 2 O 3 results from both the electronic sensitization and chemical sensitization effects of Au nanoparticles. In short, the 3D flower-like mesoporous 1%Au/In 2 O 3 possesses excellent sensitivity, selectivity, repeatability, linear relationship and long-term stability at 160 °C. Therefore, the obtained 3D flower-like mesoporous 1%Au/In 2 O 3 has great potential for ethanol gas detection. [Display omitted] • 3D flower-like mesoporous In 2 O 3 was synthesized via facile precipitation and calcination process. • 3D flower-like mesoporous Au/In 2 O 3 was prepared by sol-immobilization method. • 3D flower-like mesoporous Au/In 2 O 3 showed excellent ethanol sensing performance. [ABSTRACT FROM AUTHOR]

The formulation of substrates with reliable quantitative detection and robust molecular anchoring is crucial for surface-enhanced Raman scattering (SERS) technique. In this context, an appealing hydrophilic-hydrophobic polymer strip with Raman internal standard (IS) was generated by in-situ growing hydrophilic non-metallic black phosphorus/metal-organic frameworks (BP/ZIF-67) onto special regions of hydrophobic polydimethylsiloxane (PDMS) matrix, which dramatically promoted the concentration of target molecules. Furthermore, a specific detection of coronavirus disease 2019 (SARS-CoV-2) N-protein with a limit of 6.4 × 10−6 mg/mL was facilitated, benefiting from the selective capture rendered by the mesoporous surface of ZIF-67 and the ultra-high enhancement effect arose from BP/ZIF-67 hybrid structure-triggered charge transfer resonance process. Moreover, the extent of quantification in the SERS assay was significantly remedied due to the IS strategy. Especially, the slight local surface plasmon resonance (LSPR) capability of BP could readily provoke additional electromagnetic field to complement its powerful chemical enhancement, which was significantly superior to other non-metallic substrates. Such an upgraded platform may deliver another prospering technology for dependable virus monitoring. [Display omitted] • SERS-active polymer strip with BP/ZIF-67 for straightforward virus detection. • Comprehensive explanation of chemical-electromagnetic synergistic enrichment mechanism. • Quantitative detection of SARS-CoV-2 with LOD of 6.4 × 10−6 mg/mL was achieved. [ABSTRACT FROM AUTHOR]

Chemiresistive gas sensors have emerged as a promising generation of detection systems for identifying trace biomarker molecules in exhaled breath, potentially replacing conventional devices for early-stage disease diagnosis. However, their potential is currently limited by the absence of sensing materials that exhibit both humidity resistance and ultrasensitivity. In this study, we investigate the potential of WO 3 nanoparticles (NPs) supported by Nb 2 CTx MXene (WO 3 /Nb 2 CTx) as a highly efficient material for acetone sensing. Our results demonstrate that the synergistic interplay between WO 3 NPs and Nb 2 CTx MXene support generates an intriguing interface with chemical/electronic coupling, thereby further enhancing the gas sensing performance. The WO 3 /Nb 2 CTx sensor exhibits exceptional sensing performance for acetone, with ultrasensitivity (Ra/Rg = 2.4 at 50 ppb) and an ultrafast response time (8 s), surpassing that of WO 3 alone, while maintaining excellent stability. Moreover, the sensor exhibits outstanding response intensity, rapid response time (9 s), superior selectivity, and remarkable reversibility at a relative humidity of approximately 90 %. Additionally, we evaluate the gas-sensing properties of the sensor towards simulated exhaled breath of diabetic patients. In conclusion, our study presents a novel approach that integrates NPs and MXenes, which holds promise for the development of gas sensors with resistance to humidity interference. • WO 3 /Nb 2 CTx heterojunction is designed for acetone detection. • WO 3 /Nb 2 CTx sensor demonstrates ultrasensitive acetone detection at ∼90 % RH. • The Nb 2 CTx facilitates the generation of oxygen vacancies and enhances charge transfer. [ABSTRACT FROM AUTHOR]