Defective ZnO Nanoflowers Decorated by Ultra-Fine Pd Clusters for Low-Concentration CH4 Sensing: Controllable Preparation and Sensing Mechanism Analysis

Abstract

To detect low concentration of CH4 is indeed meaningful in industrial manufacturing, such as the petrochemical industry and natural gas catalysis, but it is not easy to detect low concentration of CH4 due to its high symmetrical and stable structure. In this work, defect-rich ZnO1−x nanoflowers (NFs) were synthesized by a two-step route so as to obtain defect-enhanced gas-sensing performance, namely hydrothermal synthesis followed by H2 treatment. In order to achieve low-concentration detection of CH4, the ultra-thin Pd clusters’ (Cs, diameter about 1–2 nm) sensitizer was synthesized and decorated onto the surface of ZnO1−x NFs. It is found that Pd Cs-2/ZnO1−x gas sensors show enhanced gas-sensing properties to CH4, even at ppm concentration level. At its optimal working temperature of 260 °C, the gas response to 50 ppm CH4 can reach 5.0 with good gas selectivity; the response and recovery time is only 16.2 and 13.8 s, respectively. In the Results, we discussed the CH4 gas-sensing mechanism deeply. Overall, it is very necessary to detect low-concentration methane safely. It is possible for further safe detection of low-concentration methane gas in the future.

ZnO based 0–3D diverse nano-architectures, films and coatings for biomedical applications

“…The nanocomposite films showed excellent mechanical and antibacterial properties displaying polymer-based nanocomposite antibacterial coating which could be applied in several fields, such as textile, leather, packaging, paper making and indoor wall coating. Chen et al 113 fabricated ZnO nanoflowers and also metal decorated nanoflowers which showed excellent sensing applications. Tang et al 114 produced ZnO NRs, nanowalls and nanoflowers via a hydrothermal route.…”

Functionalized Carbon-Nanotubes-Based Thin-Film Transistor Sensor for Highly Selective Detection of Methane at Room Temperature

“…Therefore, in order to increase the selectivity to CH 4 and reduce the cross-sensitivity to other interfering gases, the reasonable functional modification of CNTs is a promising strategy [17][18][19]. Studies have shown that nanocomposites provide high-performance gas detection [20]: VO 2 can be sensitive to CH 4 [21,22], and noble Pd has a favorable catalytic effect on CH 4 [23][24][25]. In addition, due to the transconductance of field-effect transistor (FET) sensors, the gas sensors based on the FET structure have a strong amplification effect of weak signals and can realize the detection of lower concentrations of gas molecules with high sensitivity [26][27][28].…”

Ba-Modified ZnO Nanorods Loaded with Palladium for Highly Sensitive and Rapid Detection of Methane at Low Temperatures

“…Despite this progress, it is still a challenge to develop novel CH 4 sensors to meet the growing demands (e.g., lower operating temperatures and faster response/recovery rates). Since the principle of CH 4 sensing is the catalytic oxidation of CH 4 , which is promoted by Pd, it is facile to consider the structural modification of Pd to further improve the CH 4 sensing performance [27]. In recent years, researchers have proposed an important strategy: the introduction of a second metal component as a promoter to enhance the catalytic oxidation of CH 4 at reasonably low temperatures by increasing the activity of the catalyst, which significantly improves the gas sensing performance [28][29][30].…”