Recent advances in energy-saving chemiresistive gas sensors: A review

This paper presents an overview of semiconductor materials used in gas sensors, their technology, design, and application. Semiconductor materials include metal oxides, conducting polymers, carbon nanotubes, and 2D materials. Metal oxides are most often the first choice due to their ease of fabrication, low cost, high sensitivity, and stability. Some of their disadvantages are low selectivity and high operating temperature. Conducting polymers have the advantage of a low operating temperature and can detect many organic vapors. They are flexible but affected by humidity. Carbon nanotubes are chemically and mechanically stable and are sensitive towards NO and NH3, but need dopants or modifications to sense other gases. Graphene, transition metal chalcogenides, boron nitride, transition metal carbides/nitrides, metal organic frameworks, and metal oxide nanosheets as 2D materials represent gas-sensing materials of the future, especially in medical devices, such as breath sensing. This overview covers the most used semiconducting materials in gas sensing, their synthesis methods and morphology, especially oxide nanostructures, heterostructures, and 2D materials, as well as sensor technology and design, application in advance electronic circuits and systems, and research challenges from the perspective of emerging technologies.

https://www.mdpi.com/1424-8220/20/22/6694/pdf

Semiconductor Gas Sensors: Materials, Technology, Design, and Application

This article discusses the main uses of 1D and 2D nanomaterials in the development of conductometric gas sensors based on metal oxides. It is shown that, along with the advantages of these materials, which can improve the parameters of gas sensors, there are a number of disadvantages that significantly limit their use in the development of devices designed for the sensor market.

Current Trends in Nanomaterials for Metal Oxide-Based Conductometric Gas Sensors: Advantages and Limitations. Part 1: 1D and 2D Nanostructures.

Surface acoustic wave (SAW) gas sensors are of continuous development interest to researchers due to their sensitivity, short detection time, and reliability. Among the most used materials to achieve the sensitive film of SAW sensors are metal oxide semiconductors, which are highlighted by thermal and chemical stability, by the presence on their surface of free electrons and also by the possibility of being used in different morphologies. For different types of gases, certain metal oxide semiconductors are used, and ZnO is an important representative for this category of materials in the field of sensors. Having a great potential for the development of SAW sensors, the discussion related to the development of the sensitivity of metal oxide semiconductors, especially ZnO, by the synthesis method or by obtaining new materials, is suitable and necessary to have an overview of the latest results in this domain.

https://www.mdpi.com/1424-8220/20/18/5118/pdf

ZnO Metal Oxide Semiconductor in Surface Acoustic Wave Sensors: A Review

Hydrogen (H2) has been considered as one of the cleanest renewable energy sources. However, it is still challenging to use H2 due to its hazardous flammable and explosive properties under mild conditions in the event of leakage, and the difficulty to detect or sense it through human sensory organs because of its colorless and odorless nature. Traditional detection methods are usually complicated and the testing instruments are expensive. Thus, it is of significant importance to develop sensors for H2 detection with facile operation conditions, low costs, and excellent performance (i.e., sensitivity, selectivity, and stability). To overcome the problems and for practically detecting H2 gas, metal oxide (MOx) nanomaterials have become more crucial in such a gas sensor because of the simple preparation method, high surface area, high sensitivity, and low costs. This review will focus on the recent state-of-the-art advances in resistive H2 gas sensors based on MOx nanomaterials, starting from a brief introduction of resistive gas sensors. The following sections will focus on the synthesis of different structures and types of such MOx nanomaterials, including mono/binary/ternary/ternary or more complicated MOx nanomaterials. Meanwhile, we highlight some regulation methods such as surface or inner decoration by noble or non-noble metals to improve the performance as well as summarize and compare different structures (core–shell and heterojunction), and mechanisms in H2 sensing. Finally, the opportunities and challenges of MOx-based H2 gas sensors are proposed in detail.

/pdf/advanced-development-of-metal-oxide-nanomaterials-for-h2-gas-564n02y8z5.pdf

Advanced development of metal oxide nanomaterials for H2 gas sensing applications

https://iopscience.iop.org/article/10.1149/1945-7111/ab7e23/pdf

Daniel Arulraj

Papers

Review—Resistive-Type Hydrogen Sensors Based on Zinc Oxide Nanostructures