Nanostructured SnO(2) films prepared from evaporated Sn and their application as gas sensors

Pentacenequinone-Modulated 2D GdSn-PQ Nanosheets as a Fluorescent Probe for the Detection of Enrofloxacin in Biological and Environmental Samples

The fate and effects of fluoroquinolone antibacterial (FQ) on the environment are important since there appears to be a surge in FQ resistance like enrofloxacin (ENR) in both environmental and clinical organisms. Numerous reports indicate that the sensing capabilities of these antibiotics need to be improved. Here, we have investigated the interaction of ENR with our synthesized pentacenequinone-modulated gadolinium-tin (GdSn-PQ) nanosheets and the formation of intermolecular interactions that caused the occurrence of aggregation-induced emission enhancement. The concept for designing hybrid metallic nanosheets comes from the unique features inherited from the parent organic precursor. Due to the distinct interaction between ENR and GdSn-PQ, the interstate conversion (ISC) between GdSn-PQ and ENR induces a significant wavelength shift in photoluminescence (PL), improving reliability, selectivity, and visibility compared to quenching- or AIEE-based methods without peak shifts, allowing for highly sensitive and visually detectable analyses. The fluorescence signal of GdSn-PQ exhibited a linear relationship (R2 = 0.9911), with the added ENR concentrations ranging from 5 to 90 nM, with a detection limit of 0.10 nM. We have demonstrated its potential and wide use in the detection of ENR in biological samples (human urine and blood serum) and environmental samples (tap water and seawater) with a recovery rate of 98- 108%. The current approach has demonstrated that the 2D GdSn-PQ nanosheet is a novel and powerful platform for future biological and environmental studies.

Experimental Spectroscopic Data of SnO2 Films and Powder

Powders and films composed of tin dioxide (SnO2) are promising candidates for a variety of high-impact applications, and despite the material’s prevalence in such studies, it remains of high importance that commercially available materials meet the quality demands of the industries that these materials would most benefit. Imaging techniques, such as scanning electron microscopy (SEM), atomic force microscopy (AFM), were used in conjunction with Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) to assess the quality of a variety of samples, such as powder and thin film on quartz with thicknesses of 41 nm, 78 nm, 97 nm, 373 nm, and 908 nm. In this study, the dependencies of the corresponding Raman, XPS, and SEM analysis results on properties of the samples, like the thickness and form (powder versus film) are determined. The outcomes achieved can be regarded as a guide for performing quality checks of such products, and as reference to evaluate commercially available samples.

Strategy and Future Prospects to Develop Room-Temperature-Recoverable NO2 Gas Sensor Based on Two-Dimensional Molybdenum Disulfide

Nitrogen dioxide (NO2), a hazardous gas with acidic nature, is continuously being liberated in the atmosphere due to human activity. The NO2 sensors based on traditional materials have limitations of high-temperature requirements, slow recovery, and performance degradation under harsh environmental conditions. These limitations of traditional materials are forcing the scientific community to discover future alternative NO2 sensitive materials. Molybdenum disulfide (MoS2) has emerged as a potential candidate for developing next-generation NO2 gas sensors. MoS2 has a large surface area for NO2 molecules adsorption with controllable morphologies, facile integration with other materials and compatibility with internet of things (IoT) devices. The aim of this review is to provide a detailed overview of the fabrication of MoS2 chemiresistance sensors in terms of devices (resistor and transistor), layer thickness, morphology control, defect tailoring, heterostructure, metal nanoparticle doping, and through light illumination. Moreover, the experimental and theoretical aspects used in designing MoS2-based NO2 sensors are also discussed extensively. Finally, the review concludes the challenges and future perspectives to further enhance the gas-sensing performance of MoS2. Understanding and addressing these issues are expected to yield the development of highly reliable and industry standard chemiresistance NO2 gas sensors for environmental monitoring.

Ambient Temperature CO Oxidation Using Palladium–Platinum Bimetallic Catalysts Supported on Tin Oxide/Alumina

A series of Pt-based catalysts were synthesised and investigated for ambient temperature CO oxidation with the aim to increase catalytic activity and improve moisture resistance through support modification. Initially, bimetallic PtPd catalysts supported on alumina were found to exhibit superior catalytic activity compared with their monometallic counterparts for the reaction. Following an investigation into the effect of Pt/Pd ratio, a composition of 0.1% Pt/0.4% Pd was selected for further studies. Following this, SnO2/Al2O3 supports were synthesised from a variety of tin oxide sources. Catalytic activity was improved using sodium stannate and tin oxalate precursors compared with a traditional tin oxide slurry. Catalytic activity versus tin concentration was found to vary significantly across the three precursors, which was subsequently investigated by X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDX).

Fabrication of a SnO2-based acetone gas sensor enhanced by molecular imprinting

This work presents a new route to design a highly sensitive SnO2-based sensor for acetone gas enhanced by the molecular imprinting technique. Unassisted and acetone-assisted thermal synthesis methods are used to synthesis SnO2 nanomaterials. The prepared SnO2 nanomaterials have been characterized by X-ray powder diffraction, scanning electron microscopy and N2 adsorption-desorption. Four types of SnO2 films were obtained by mixing pure deionized water and liquid acetone with the two types of as-prepared powders, respectively. The acetone gas sensing properties of sensors coated by these films were evaluated. Testing results reveal that the sensor coated by the film fabricated by mixing liquid acetone with the SnO2 nanomaterial synthesized by the acetone-assisted thermal method exhibits the best acetone gas sensing performance. The sensor is optimized for the smooth adsorption and desorption of acetone gas thanks to the participation of acetone both in the procedure of synthesis of the SnO2 nanomaterial and the device fabrication, which results in a distinct response-recovery behavior.

Low-temperature self-catalytic growth of tin oxide nanocones over large areas

Nanoscale texturing has been studied for various applications, but most of the methods used to make these nanostructures are expensive and not easily scalable. Some of these methods require etching steps or high-temperature processes, which limit the processes to certain materials, such as silicon. In this study, we report a non-etching nanoscale texturing technique that allows for controlled oxidation to create tin oxide nanocones over large areas. Similar results are obtained on different substrates, such as silicon, aluminum foil, quartz, and polyimide film, and this method can be employed at temperatures as low as 220 °C in ambient pressure. This simple and scalable nanotexturing process improves the anti-reflection effect in photovoltaic devices. The light absorption of a polycrystalline silicon substrate, a widely used photovoltaic material, is increased by 30% over the wavelength range of 400-850 nm after fabricating nanocones on the surface.

Semiconductor gas sensors: dry synthesis and application

Since the development of the first chemoresistive metal oxide based gas sensors, transducers with innovative properties have been prepared by a variety of wet- and dry-deposition methods. Among these, direct assembly of nanostructured films from the gas phase promises simple fabrication and control and with the appropriate synthesis and deposition methods nm to μm thick films, can be prepared. Dense structures are achieved by tuning chemical or vapor deposition methods whereas particulate films are obtained by deposition of airborne, mono- or polydisperse, aggregated or agglomerated nanoparticles. Innovative materials in non-equilibrium or sub-stoichiometric states are captured by rapid cooling during their synthesis. This Review presents some of the most common chemical and vapor-deposition methods for the synthesis of semiconductor metal oxide based detectors for chemical gas sensors. In addition, the synthesis of highly porous films by novel aerosol methods is discussed. A direct comparison of structural and chemical properties with sensing performance is given.

Laser direct writing of nanoreliefs in Sn nanofilms

High-resolution (approximately 200 nm) nanoreliefs, which possess a controllable height change (Deltah, up to film thickness) and transmittance or reflectance, have been successfully fabricated in 12-nm-thick Sn films by using 532 nm pulsed laser direct writing. Different from current micro/nanofabrication techniques, the height change of the nanoreliefs is generated by a laser-induced-thickening process. The majority of the height change comes from a balling and coarsening effect rather than oxidation of grains. Because both optical density and Deltah of the nanoreliefs are almost linear to laser power, the optical images can highly resemble the topographic images. This technique is useful for fabricating complicated nanorelief structures and fine images.