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In this study, nanosilica was utilized as a substrate for the deposition of polymeric layers imprinted with copper-(II) ions, which were used for the colorimetric detection of Cu-(II). The nanosilica was first prepared using the Stober method and then used in an in situ polymerization of aminopropyltriethoxysilane and tetraethyl orthosilicate in the presence of the template copper ions. Following the elution process, the polymer was washed with a proper solution to obtain the Cu-(II)-imprinted polymers on nanosilica (SiO2@MIP), which were characterized by transmission electron microscopy to reveal the diameter of the silica core to be approximately 350 nm, and the polymeric layers were about 40 nm in thickness. The SiO2@MIP was successfully employed in the colorimetric detection of Cu-(II) in aqueous solutions with concentrations ranging from 0.001 to 0.1 M, using xylenol orange as the colorimetric indicator. The color change could be easily observed by the naked eye, with colors shifting from yellowish-orange to dark purple. The sensing signal was quantitatively assessed using UV–vis absorbance, and the limit of detection for Cu-(II) was determined to be 0.064 mg/mL. Additionally, SiO2@MIP was demonstrated to be highly specific for the adsorption of Cu-(II) with the imprinted cavities. The proposed Cu-(II) imprinted polymers show promise in real-world detection of Cu-(II) with advantages of low cost, user-friendliness, and high selectivity. [ABSTRACT FROM AUTHOR]

In this study, a gas sensor consisting of Ag nanowires (Ag NWs) dispersed on surface of monolayer graphene was prepared by spray coating. The sensing performance was investigated in terms of response sensitivity and recovery speed at room temperature with the assistance of UV illumination. The correlation between initial volume of Ag NWs solution and final coverage of Ag NWs was built. A series of systematical sensing tests indicated the sensing performance was greatly dependent on the coverage of Ag NWs, and the sensor consisted of 4.8% Ag NWs coverage exhibited highest response upon NO2 exposure. Raman spectrum revealed electron-donor role of Ag NWs, which facilitates adsorption of NO2 on graphene resulting in a doubled response compared to that of bare graphene (40% for 5 ppm of NO2). In addition, with photoexcitation using UV illumination, the sensor exhibited recovery time of 4 min, which was much faster than that of exposure to NO2 without UV illumination (15 min at the same concentration of NO2). This approach appeared to be highly practical to overcome the problematic low recovery speed of graphene-based sensors. [ABSTRACT FROM AUTHOR]

In this study, S-deficient MoS 2 was prepared using proton irradiation and then applied as sensing materials for the detection of NO 2 gas. First, bulk MoS 2 was treated by ultrasonics to produce 2D nanosheets of MoS 2 , which were subsequently bombarded by a flux of high-energy protons, resulting in the appearance of structural defects throughout MoS 2 . The proton fluxes were adjusted to different densities of 1 × 10 11 , 1 × 10 12 , 1 × 10 13 , and 1 × 10 14 ions/cm 2 . The effects of proton irradiation on the defects, also referred to as atomic vacancies, were systematically investigated using Raman measurements to locate the E 1 2g and A 1g modes and X-ray photoelectron spectroscopy to determine the binding energy of Mo 3d and S 2p orbitals. It was revealed that the density of proton irradiation greatly affects the degree of S atom vacancies in irradiated MoS 2 , while also enhancing the n-type semiconducting behaviors of MoS 2 . The vacancy-rich MoS 2 was then demonstrated to exhibit a higher response to NO 2 gas compared to that of nonirradiated MoS 2 , showing a 4-fold increase in response within a concentration range from 1 to 20 ppm. These results could pave the way for new approaches to fabricating sensing materials., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)