Stable and sensitive amino-functionalized graphene/polyaniline nanofiber composites for room-temperature carbon dioxide sensing

In situ synthesis of long tubular water-dispersible polyaniline with core/shell gold and silver@graphene oxide nanoparticles for gas sensor application

Gold nanoparticles (Au NPs) with graphene oxide (GO) shell (Au@GO), silver nanoparticles (Ag NPs) with GO shell (Ag@GO), and gold silver nanoparticles (AuAgNPs) with GO shell (AuAg@GO) were synthesized employing a cationic surfactant. The prepared core@shell structures were used for in situ synthesis of long tubular polyaniline structures employing cetyl trimethyl ammonium bromide (CTAB) as a soft template. This process led to a notable enhancement in the tubular nanostructure of PANI, extending its length beyond 10 μm, in the case of using core/shell Au@GO, Ag@GO, and AuAg@GO structures. To evaluate their applicability and compatibility, the dispersibility of these nanocomposites was assessed in three distinct solvents: water, dimethyl sulfoxide (DMSO), and N-Methyl-2-pyrrolidone (NMP). Subsequently, the dedoping of PANI within the prepared nanocomposites was scrutinized using UV-Visible (UV-Vis) spectroscopy, which revealed a reduction in the I750/I315 ratio from 1.00 to 0.66 when subjected to water and NMP solvents, respectively. Notably, the dedoping of the AuAg@GO/PANI nanocomposite was predominantly observed in NMP, attributable to the presence of hydrogen bonding interactions and the basic properties of NMP. In terms of ionic conductivity, it was observed that the prepared nanocomposite exhibited its highest conductivity in a water-based medium, registering at 1982 μs. Furthermore, the AuAg@GO/PANI nanocomposite exhibited superior sensing capabilities in comparison to PANI-based gas sensor devices, particularly when exposed to acetone, CO2, NO2, and H2S. Remarkably, at room temperature (25 °C), the AuAg@GO/PANI nanocomposite displayed rapid response and recovery times, with values of 279 s, 431 s, 335 s, and 509 s for 1 ppm concentrations of CO2, NO2, H2S, and acetone, respectively. The sensitivity of these sensors towards acetone, CO2, NO2, and H2S, was quantified by analyzing the slope of the response versus the target gas concentration, revealing the AuAg@GO/PANI nanocomposite to exhibit the highest sensitivity, particularly towards NO2.

A Review on Electrospun Nanofiber Composites for an Efficient Electrochemical Sensor Applications

The present review article discusses the elementary concepts of the sensor mechanism and various types of materials used for sensor applications. The electrospinning method is the most comfortable method to prepare the device-like structure by means of forming from the fiber structure. Though there are various materials available for sensors, the important factor is to incorporate the functional group on the surface of the materials. The post-modification sanction enhances the efficiency of the sensor materials. This article also describes the various types of materials applied to chemical and biosensor applications. The chemical sensor parts include acetone, ethanol, ammonia, and CO2, H2O2, and NO2 molecules; meanwhile, the biosensor takes on glucose, uric acid, and cholesterol molecules. The above materials have to be sensed for a healthier lifestyle for humans and other living organisms. The prescribed review articles give a detailed report on the Electrospun materials for sensor applications.

Carbon Dioxide Sensing with Langmuir–Blodgett Graphene Films

Graphene has become a material of choice for an increasing number of scientific and industrial applications. It has been used for gas sensing due to its favorable properties, such as a large specific surface area, as well as the sensitivity of its electrical parameters to adsorption processes occurring on its surface. Efforts are ongoing to produce graphene gas sensors by using methods that are compatible with scaling, simple deposition techniques on arbitrary substrates, and ease of use. In this paper, we demonstrate the fabrication of carbon dioxide gas sensors from Langmuir–Blodgett thin films of sulfonated polyaniline-functionalized graphene that was obtained by using electrochemical exfoliation. The sensor was tested within the highly relevant concentration range of 150 to 10,000 ppm and 0% to 100% at room temperature (15 to 35 °C). The results show that the sensor has both high sensitivity to low analyte concentrations and high dynamic range. The sensor response times are approximately 15 s. The fabrication method is simple, scalable, and compatible with arbitrary substrates, which makes it potentially interesting for many practical applications. The sensor is used for real-time carbon dioxide concentration monitoring based on a theoretical model matched to our experimental data. The sensor performance was unchanged over a period of several months.

Nanofibers of Polyaniline and Cu(II)-l-Aspartic Acid for a Room-Temperature Carbon Monoxide Gas Sensor

In the present study, the carbon monoxide (CO) sensing property of Cu(II)-l-aspartic acid nanofibers/polyaniline (PANI) nanofibers composite was investigated at room temperature. The nanofiber composite was formed through the ultrasound mixing of emeraldine salt PANI nanofibers and Cu(II)-l-aspartic acid nanofibers, which were synthesized by using a polymerization process and simple self-assembly method, respectively. The nanofibers composite demonstrated a branched structure in which the Cu(II)-l-aspartic acid nanofiber framework is similar to the trunk of a tree and the polyaniline nanofibers is like its branches. It seems that this special structure and one-dimension/one-dimension interface are suitable for gas adsorption and sensing. The performance of the prepared sensor toward CO gas was investigated at room temperature in a wide concentration range (200-8000 ppm). The experimental results indicate that the incorporation of amino acid-based copper metal-biomolecule framework nanofibers to PANI nanofibers enhances the response value (12.41% to 4000 ppm), yielding good selectivity and acceptable response and recovery characteristics (220 s/240 s) at room temperature. The detection limit of Cu(II)-l-aspartic acid nanofibers/PANI nanofibers sensor for carbon monoxide is obtained at 120 ppm.