Enhancement of Room Temperature Ethanol Sensing by Optimizing the Density of Vertically Aligned Carbon Nanofibers Decorated with Gold Nanoparticles

Abstract

An ethanol gas sensor based on carbon nanofibers (CNFs) with various densities and nanoparticle functionalization was investigated. The CNFs were grown by means of a Plasma-Enhanced Chemical Vapor Deposition (PECVD), and the synthesis conditions were varied to obtain different number of fibers per unit area. The devices with a larger density of CNFs lead to higher responses, with a maximal responsivity of 10%. Furthermore, to simultaneously improve the sensitivity and selectivity, CNFs were decorated with gold nanoparticles by an impaction printing method. After metal decoration, the devices showed a response 300% higher than pristine devices toward 5 ppm of ethanol gas. The morphology and structure of the different samples deposited on a silicon substrate were characterized by TEM, EDX, SEM, and Raman spectroscopy, and the results confirmed the presence of CNF decorated with gold. The influence of operating temperature (OT) and humidity were studied on the sensing devices. In the case of decorated samples with a high density of nanofibers, a less-strong cross-sensitivity was observed toward a variation in humidity and temperature.

The sensitivity enhancement of TiO2-based VOCs sensor decorated by gold at room temperature

“…Both I-V curves show Schottky contact which indicates same contact before and after the decoration with gold nanoparticles. Due to the sparse nature of the gold nanoparticles, they had only a small impact on the conductivity of the sample [9,24]. The I-V characteristic of the Au-TiO 2 sample at different temperatures has been demonstrated in figure 7(b) in order to investigate the electrical contact of the electrodes [25].…”

“…These noble metals change the electronic characteristics of TiO 2 , redesign the crystalline phases, and increase the density of surface defects. Thus, noble metals act as activators to improve gas response and selectivity and reduce the response and recovery time and operating temperature [8,9]. in addition, noble metals have a greater impact on the gas sensing of TiO 2 nanostructures than other structures [5,8].…”

Gas Selectivity Enhancement Using Serpentine Microchannel Shaped with Optimum Dimensions in Microfluidic-Based Gas Sensor

“…where I n (t), min (I(t)) and max (I(t)) are the normalized, minimum and maximum current at all simulation times, respectively. Selectivity is the ability to identify and distinguish gas A from gas B; it is represented by the ratio of the sensor signals induced by gas A and gas B [36,37]. The selectivity of a microfluidic-based gas sensor can be determined based on the difference between the normalized currents of two gases, as in the following equation:…”

A Highly Sensitive Surface-Modified Porous Carbon Nanotube-Based Sensor for Ammonia Gas Detection

“…As a result, several researchers have focused heavily on developing gas sensors using techniques other than those that are costly, like gas chromatography. , Chemical-resistive sensors are straightforward and have benefits of being transforming into a microsensor; − thus, the approach for electrochemical sensors and chemical resistance is appealing, such as a gas sensor employing metal oxides, graphene, − and multilayer carbon tubes. − Due to their sensitivity to a variety of gases, ability to operate at room temperature, incredibly low detection threshold, and low power requirements, CNT chemical resistance sensors are frequently utilized. Due to their high conductivity and internal gas detecting characteristics, CNTs have been utilized as sensors for chemical resistor-based sensors, which have the benefit of forming a compact sensing system. , The efficiency of gas detection may be improved by novel measuring techniques, signal processing, and sensor technology advancements.…”