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This work emphasizes the gas sensing capabilities of MoS2/PEDOT:PSS nanohybrid-based sensors, offering a prominent candidate for detecting volatile organic compounds (VOCs) at room temperature. The MoS2/PEDOT:PSS composite material is synthesized by combining commercial PEDOT:PSS with MoS2 produced via hydrothermal synthesis using ultrasonication for mechanical mixing. Further, the pristine PEDOT:PSS, MoS2, and MoS2/PEDOT:PSS samples were extensively characterized using various techniques to obtain detailed information about their structural, compositional, and morphological properties. The study reveals that the MoS2/PEDOT:PSS composite exhibited the highest sensitivity among the tested materials with a 56.29% response at 500 ppm of ethanol. The response of the MoS2/PEDOT:PSS sensor increases from 12.24% to 56.29% as the concentration of analyte gas increases from 25 to 500 ppm. Also, repeatability-, sensitivity-, and humidity-based analyses were performed for the evaluation of the sensor. The response and recovery times of the MoS2/PEDOT:PSS nanohybrid sensor are 8.2 and 2.5 s, respectively. The repeatability analysis demonstrated stable performance across multiple tests with percent deviations of ±0.04 for PEDOT:PSS, ± 0.35 for MoS2, and ±0.08 for MoS2/PEDOT:PSS under ambient conditions. The computational study reveals that the EDOT:SS/MoS2 (002) composite exhibits strong oxygen adsorption energies of −11.61 eV, indicating enhanced adsorption capabilities. In contrast, MoS2 (002) and PEDOT:PSS show lower energies of −9.22 and −11.08 eV, respectively. Additionally, VOC adsorption on oxygen preadsorbed EDOT:SS/MoS2 (002) shows methanol and ethanol with strong affinities, while toluene and hexane exhibit weaker interactions. These computational findings highlight and support the potential of the MoS2/PEDOT:PSS composite for gas sensing applications. [ABSTRACT FROM AUTHOR]

The exceptional properties of two-dimensional (2D) materials have contributed to significant advancements in optoelectronics (OPs). While various effective methods exist for enhancing photodetector (PD) responsivity, the constrained spectral range persists as a limiting factor of the device. This study demonstrates the ability to create a p-n heterojunction between 2D molybdenum disulfide (MoS2) nanosheets and polyaniline (PANI) for metal–semiconductor–metal (MSM) PDs using a solution-processed approach on PET substrate. We evaluated the MoS2-PANI nanohybrid PD device across the visible and ultraviolet (UV) spectra. When exposed to UV and visible light irradiation, the estimated maximum responsivities of the fabricated PD are 29.98 AW–1 and 73.32 AW–1, respectively. This is significant when compared with the earlier research on broadband PDs. We create a pathway for developing highly responsive broadband PDs by integrating organic and inorganic materials. These innovations hold promise for various applications in security, healthcare, and beyond. [ABSTRACT FROM AUTHOR]

A chemical vapor-deposition-based pyrolysis method is used for synthesizing uniformly nitrogen-doped carbon frameworks nucleated through any of the three different transition-metal (Fe, Co, and Ni) nanoparticles. Although a fixed amount of nitrogen precursor was used during the synthesis of all the samples, the samples showed varying nitrogen concentrations in the carbon framework. The N-doping in graphitic carbon shells hugely enhanced the amount of defects, which boosted the surface area and porosity, and unveiled the active sites necessary for catalytic reaction. Among all the samples used for studying oxygen reduction reaction (ORR), the sample with Ni-embedded N-doped carbon framework exhibits the highest half-wave potential (E1/2) of ∼0.886 V versus reversible hydrogen electrode (RHE) in an aqueous 0.1 M KOH solution, in comparison with the other two samples containing Fe or Co, and also with the commercially available Pt/C sample (∼0.854 V). This indicates that our samples can be used as efficient oxygen adsorbers under atmospheric conditions. Utilizing this advantage, we have successfully showcased our samples as sensors for the detection of various volatile organic compound (VOC) gases at room temperature. The VOCs that we used for this study include ethanol, propane-2-ol, acetone, toluene, hexane, and cyclohexane gases. Among all of the samples, the sample containing cobalt nanoparticles displayed the highest response for gas sensing. Furthermore, the response toward ethanol sensing is the highest in comparison to the other VOCs. Additionally, the response toward ethanol was examined at different relative humidity levels of 11–95% to ensure the applicability of our samples in real-time scenarios. Therefore, our samples are promising candidates for important applications, such as efficient energy conversion and gas sensing. [ABSTRACT FROM AUTHOR]

The SnO-BaTiO3 bi-layered heterostructured chemiresistive sensor exhibits promising potential for detecting volatile organic compounds (VOCs) at room temperature. This study explores the different designs and configurations of a bi-layered heterostructure platform. The performance of the SnO-BaTiO3 sensor was evaluated under humid and VOC atmospheres. The SnO-BaTiO3 bilayer sensor shows a response of 202% at 65% RH and significantly increased to approximately 562% at 95% RH, indicating its sensitivity to both toluene and humidity. The SnO-BaTiO3 device architecture demonstrated excellent repeatability and stability with good response (44 s) and recovery (7 s) times towards the 1000 ppm toluene concentration. For real-time sensing applications, it is essential for the SnO-BaTiO3 bilayer sensor to work reliably at room temperature and to detect VOCs under ambient conditions accurately. It might be used to regulate interior air quality, detect environmental damage, and monitor real-time VOC emissions resulting from industrial activities. Moreover, the bilayer sensor can execute the gas-sensing procedure at room temperature; it can run on a small amount of electricity and consume less energy than conventional sensors. [ABSTRACT FROM AUTHOR]

In this study, the fabrication of an ultrahigh selective NH3 gas sensor based on RGO/WO3 nanocomposite has been proposed. The hydrothermal method was employed to synthesize the RGO/WO3 nanocomposite. The formation of RGO/WO3 nanocomposite and the elemental composition, structure and morphology of the as-synthesized materials were confirmed through an array of analytical techniques, including XRD, Raman, FT-IR, XPS and TEM. For gas sensing applications, pure RGO and RGO/WO3 have effectively spin-coated onto the interdigitated electrodes (IDE's) based on fluorine doped tin oxide (FTO) respectively, and their sensitivity towards NH3 was tested. Gas sensing characteristics of prepared materials were analyzed at room temperature (25 °C) under different relative humidity (RH) levels. The developed RGO/WO3 sensor was subjected to different NH3 concentrations, demonstrating a high sensing response of 89% towards 500 ppm NH3 under 11%–97%–11% RH conditions. Notably, the sensor exhibited rapid response and recovery times with an average response time of 92 s and recovery time of 26 s when exposed to 500 ppm NH3 under the specified RH conditions. To gauge the material selectivity, the prepared nanocomposite was exposed to a range of volatile organic compounds and the results showcased the sensor's remarkable selectivity and sensitivity specifically toward NH3 vapor. This superior performance can be attributed to the abundant active sites and the excellent electron transport properties inherent to the RGO component. Importantly, the RGO/WO3 sensor displayed high reproducibility and consistent responses, with minimal degradation (1.98% degradation) over 30 d at 11%–97%–11% RH. Furthermore, we examined the sensor's response with varying levels of relative humidity to assess its potential for real-world applications. The sensor exhibited extremely low power consumption, outperforming a commercially available metal oxide sensor while operating at ambient temperature. The robust performance of RGO/WO3 coupled with low power requirements and ambient temperature operation, positions it as a promising candidate for next-generation gas sensing technologies. [ABSTRACT FROM AUTHOR]

Herein, the monoclinic phase of tungsten oxide (γ-WO3) was successfully obtained after annealing hydrothermally synthesised WO3 powder at 500 °C. As per the result obtained from the N2 adsorption–desorption isotherm, the material has been identified as mesoporous with a specific surface area of 3.71 m2 g−1 from BET (Brunauer–Emmett–Teller) analysis. Moreover, the average pore size (49.52 nm) and volume (0.050 cm3 g−1) were also determined by the BJH (Barrett–Joyner–Halenda) method. FE-SEM (field emission scanning electron microscopy) and HR-TEM (high resolution transmission electron microscopy) have confirmed the formation of nanoplates with an average diameter of approximately 274 nm. Raman spectroscopy has shown peaks at the lower wavenumber region (270 cm−1 and 326 cm−1) and the higher wavenumber region (713 cm−1 and 806 cm−1) for O–W–O bending modes and stretching modes, respectively. The combined effect of relative humidity (RH-11%–RH-95%–RH-11%) and NH3 (150 ppm, 300 ppm, 450 ppm, 600 ppm, 700 ppm, and 800 ppm) was investigated in this reported work. The synthesised γ-WO3 has shown highly responsive behaviour for humidity of 96.5% (RH-11%–95%) and NH3 sensing (under humidity) of 97.4% (RH-11%–95% with 800 ppm NH3). The response and recovery time were calculated as 15 s and 52 s, and 16 s and 54 s for humidity, and NH3 under humidity, respectively. The experimental findings demonstrated that the resistance of the sensor depends on the concentration of NH3 and humidity. Moreover, γ-WO3 has been investigated as a promising catalyst for the dye degradation of methylene blue (MB) with a degradation efficiency of 72.82% and methyl orange (MO) with a degradation efficiency of 53.84% under visible light exposure. This dye degradation occurred within 160 min in the presence of a catalyst under visible light irradiation. [ABSTRACT FROM AUTHOR]

Current work describes eco-friendly synthesis of cobalt ferrite (CoFe2O4) nanoparticles utilizing the flower and leaves extract of Hibiscus rosa-sinensis by chemical co-precipitation method and explored the behavior of CoFe2O4 nanoparticles on humidity sensing for humidity range 15% to 98% at room temperature. The cubic spinel structure of synthesized CoFe2O4 nanoparticles suggests a porous complex shape with an average crystalline size of 23.85 nm. Elemental analysis reveals no signs of impurity. Thermogravimetric analysis and differential thermal analysis showed that the material experienced a transformation toward thermal stability. CoFe2O4 nanoparticles as sensing medium were found to have a practical sensitivity of 40% relative humidity in the atmosphere and a response/recovery time of 5.31/7.75 seconds, respectively. CoFe2O4 nanoparticles are stable over time, according to the findings. CoFe2O4 nanoparticles humidity sensing performance demonstrates their suitability for room temperature-based humidity sensors. A general representation of the synthesis of CoFe2O4 nanoparticles [ABSTRACT FROM AUTHOR]