High-Performance Schottky Diode Gas Sensor Based on the Heterojunction of Three-Dimensional Nanohybrids of Reduced Graphene Oxide–Vertical ZnO Nanorods on an AlGaN/GaN Layer

270

100

Toxic gases, such as NOx, SOx, H2S and other S-containing gases, cause numerous harmful effects on human health even at very low gas concentrations. Reliable detection of various gases in low concentration is mandatory in the fields such as industrial plants, environmental monitoring, air quality assurance, automotive technologies and so on. In this paper, the recent advances in electrochemical sensors for toxic gas detections were reviewed and summarized with a focus on NO2, SO2 and H2S gas sensors. The recent progress of the detection of each of these toxic gases was categorized by the highly explored sensing materials over the past few decades. The important sensing performance parameters like sensitivity/response, response and recovery times at certain gas concentration and operating temperature for different sensor materials and structures have been summarized and tabulated to provide a thorough performance comparison. A novel metric, sensitivity per ppm/response time ratio has been calculated for each sensor in order to compare the overall sensing performance on the same reference. It is found that hybrid materials-based sensors exhibit the highest average ratio for NO2 gas sensing, whereas GaN and metal-oxide based sensors possess the highest ratio for SO2 and H2S gas sensing, respectively. Recently, significant research efforts have been made exploring new sensor materials, such as graphene and its derivatives, transition metal dichalcogenides (TMDs), GaN, metal-metal oxide nanostructures, solid electrolytes and organic materials to detect the above-mentioned toxic gases. In addition, the contemporary progress in SO2 gas sensors based on zeolite and paper and H2S gas sensors based on colorimetric and metal-organic framework (MOF) structures have also been reviewed. Finally, this work reviewed the recent first principle studies on the interaction between gas molecules and novel promising materials like arsenene, borophene, blue phosphorene, GeSe monolayer and germanene. The goal is to understand the surface interaction mechanism.

Section: Recent Advances In So2 Gas Detectionmentioning

confidence: 99%

Recent Advances in Electrochemical Sensors for Detecting Toxic Gases: NO2, SO2 and H2S

Khan

Rao

2019

270

100

“…A composite material is a material made from two or more constituent materials with significantly different physical or chemical properties that, when combined, produce a material with different characteristics from the individual components. Different composite materials based on two-dimensional materials have been used to design gas sensors [26,27,72,102,103,104,105,106,107]. Metals, polymers and ceramics have been added as a second phase to these two-dimensional materials.…”

Section: Two-dimensional Materials Used In Gas Sensorsmentioning

confidence: 99%

“…Hybrid two-dimensional materials are advanced multifunctional materials that have outstanding physical and chemical properties and are extensively considered for applications such as energy storage, energy conversion, energy harvesting technologies, and sensors [101,108]. A list of composite and/or hybrid materials using two-dimensional materials [101,102,103,104,105,106,107] that have been used in gas sensing is summarized in Table 4.…”

Section: Two-dimensional Materials Used In Gas Sensorsmentioning

confidence: 99%

“…However, the inherent disadvantage of graphene is its zero bandgap, which reduces its sensitivity and selectivity to a wide range of analytes. To optimize these capabilities of the gas sensors, vertically aligned two-dimensional structures [77,106], surface chemical functionalization [20,92], as well as two-dimensional heterostructures [12,13,14] and nanocomposites [26,27,72,107,108] have been developed. Unfortunately, these techniques do not favor long-term stability in the gas sensors, so by adding substitutional impurities [33,83] in the crystalline lattice of the two-dimensional material, the electrical conductivity of the sensitive material is modulated, and reliable and reproducible sensors can be implemented.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Electrical Properties of Two-Dimensional Materials Used in Gas Sensors

Vargas-Bernal

2019

In the search for gas sensing materials, two-dimensional materials offer the possibility of designing sensors capable of tuning the electronic band structure by controlling their thickness, quantity of dopants, alloying between different materials, vertical stacking, and the presence of gases. Through materials engineering it is feasible to study the electrical properties of two-dimensional materials which are directly related to their crystalline structure, first Brillouin zone, and dispersion energy, the latter estimated through the tight-binding model. A review of the electrical properties directly related to the crystalline structure of these materials is made in this article for the two-dimensional materials used in the design of gas sensors. It was found that most 2D sensing materials have a hexagonal crystalline structure, although some materials have monoclinic, orthorhombic and triclinic structures. Through the simulation of the mathematical models of the dispersion energy, two-dimensional and three-dimensional electronic band structures were predicted for graphene, hexagonal boron nitride (h-BN) and silicene, which must be known before designing a gas sensor.

“…NO 2 seems to be the most investigated room temperature sensing target, not only because its toxicity, but also its electrophilic characteristics that improve the gas chemical adsorption reaction on the surface of sensing materials. Many efforts have been dedicated to control the structures of 3D rGO/MOx sensing materials for enhanced NO 2 sensing properties at room temperature [ 65 , 76 , 79 , 80 , 84 , 90 , 92 , 106 , 107 , 108 ].…”

Section: Applications Of 3d Graphene/mox Hybrids For Room Temperatmentioning

confidence: 99%

3D Architectured Graphene/Metal Oxide Hybrids for Gas Sensors: A Review

Xia

Chen

et al. 2018

Graphene/metal oxide-based materials have been demonstrated as promising candidates for gas sensing applications due to the enhanced sensing performance and synergetic effects of the two components. Plenty of metal oxides such as SnO2, ZnO, WO3, etc. have been hybridized with graphene to improve the gas sensing properties. However, graphene/metal oxide nanohybrid- based gas sensors still have several limitations in practical application such as the insufficient sensitivity and response rate, and long recovery time in some cases. To achieve higher sensing performances of graphene/metal oxides nanocomposites, many recent efforts have been devoted to the controllable synthesis of 3D graphene/metal oxides architectures owing to their large surface area and well-organized structure for the enhanced gas adsorption/diffusion on sensing films. This review summarizes recent advances in the synthesis, assembly, and applications of 3D architectured graphene/metal oxide hybrids for gas sensing.