Resistive Chemosensors for the Detection of CO Based on Conducting Polymers and Carbon Nanocomposites: A Review

Abstract

Nanocomposite materials have seen increased adoption in a wide range of applications, with toxic gas detection, such as carbon monoxide (CO), being of particular interest for this review. Such sensors are usually characterized by the presence of CO absorption sites in their structures, with the Langmuir reaction model offering a good description of the reaction mechanism involved in capturing the gas. Among the reviewed sensors, those that combined polymers with carbonaceous materials showed improvements in their analytical parameters such as increased sensitivities, wider dynamic ranges, and faster response times. Moreover, it was observed that the CO reaction mechanism can differ when measured in mixtures with other gases as opposed to when it is detected in isolation, which leads to lower sensitivities to the target gas. To better understand such changes, we offer a complete description of carbon nanostructure-based chemosensors for the detection of CO from the sensing mechanism of each material to the water solution strategies for the composite nanomaterials and the choice of morphology for enhancing a layers’ conductivity. Then, a series of state-of-the-art resistive chemosensors that make use of nanocomposite materials is analyzed, with performance being assessed based on their detection range and sensitivity.

Fabrication of a Novel (PVDF/MWCNT/Polypyrrole) Antifouling High Flux Ultrafiltration Membrane for Crude Oil Wastewater Treatment

“…Thus, when the MWCNT percentage increased for PPC-0.3, the PPy layer thicknesses decreased, while for less MWCNT at PPC-0.05, the layer of PPy on MWCNT was increased; thus, more distribution of PPy amount existed on the surface of MWCNTs, similar results were reported by Baghdadi et al [63]. In the chemical oxidation of the MWCNT/PPy nanocomposite during membrane fabrication, PPy-π electrons in the conjugated bond are removed, so benzenoid structure local relaxation into a quinoid form occurs and consequently creating a radical pair leading to the appearance of a positive charge [60][61][62]. Thus, the positively charged MWCNT/PPy transforms the negatively charged pristine PVDF membrane surface into a positively charged one.…”

“…In the chemical oxidation of the MWCNT/PPy nanocomposite during membrane fabrication, PPy-π electrons in the conjugated bond are removed, so benzenoid structure local relaxation into a quinoid form occurs and consequently creating a radical pair leading to the appearance of a positive charge [60][61][62]. Thus, the positively charged MWCNT/PPy transforms the negatively charged pristine PVDF membrane surface into a positively charged one.…”

Impact of MW-CNT/polymer composites matrix type on the electrical and gas-sensitive properties

“…The sensory effects of the prepared nanocomposites were determined by the change in their resistance after exposure to CH 4, CO, and propane gases. [28][29][30][31][32][33][34] The sensitivity was first tested in air, followed by resistance measurements in methane, propane, and carbon monoxide. In this research work, three nanocomposites -Epoxy/x MW-CNT (x = 4%), Silicone/x MWCNTs (x = 4%), PU/x MWCNTs (x = 4%) were fabricated, and the gas-sensitive effect investigated.…”