Bigiani Lorenzo, Zappa Dario, Maccato Chiara, Gasparotto Alberto, Sada Cinzia, Comini Elisabetta, Barreca Davide
Department of Chemical Sciences, Padova University and INSTM, 35131 Padova, Italy.
Sensor Lab, Department of Information Engineering, Brescia University, 25133 Brescia, Italy.
Nanomaterials (Basel). 2020 Mar 11;10(3):511. doi: 10.3390/nano10030511.
Among oxide semiconductors, -type MnO systems have been exploited in chemo-resistive sensors for various analytes, but their use in the detection of H, an important, though flammable, energy vector, has been scarcely investigated. Herein, we report for the first time on the plasma assisted-chemical vapor deposition (PA-CVD) of MnO nanomaterials, and on their on-top functionalization with Ag and SnO by radio frequency (RF)-sputtering, followed by air annealing. The obtained MnO-Ag and MnO-SnO nanocomposites were characterized by the occurrence of phase-pure tetragonal α-MnO (hausmannite) and a controlled Ag and SnO dispersion. The system functional properties were tested towards H sensing, yielding detection limits of 18 and 11 ppm for MnO-Ag and MnO-SnO specimens, three orders of magnitude lower than the H explosion threshold. These performances were accompanied by responses up to 25% to 500 ppm H at 200 °C, superior to bare MnO, and good selectivity against CH and CO as potential interferents. A rationale for the observed behavior, based upon the concurrence of built-in Schottky (MnO/Ag) and - junctions (MnO/SnO), and of a direct chemical interplay between the system components, is proposed to discuss the observed activity enhancement, which paves the way to the development of gas monitoring equipments for safety end-uses.
在氧化物半导体中，-型MnO体系已被用于各种分析物的化学电阻传感器，但它们在检测氢气（一种重要的能源载体，尽管易燃）方面的应用却鲜有研究。在此，我们首次报道了MnO纳米材料的等离子体辅助化学气相沉积（PA-CVD），以及通过射频（RF）溅射对其进行Ag和SnO的表面功能化，随后进行空气退火。所获得的MnO-Ag和MnO-SnO纳米复合材料的特征是出现了纯相四方α-MnO（黑锰矿）以及可控的Ag和SnO分散。对该体系的功能特性进行了氢气传感测试，MnO-Ag和MnO-SnO样品的检测限分别为18 ppm和11 ppm，比氢气爆炸阈值低三个数量级。这些性能还伴随着在200°C下对500 ppm氢气的响应高达25%，优于裸MnO，并且对作为潜在干扰物的CH和CO具有良好的选择性。基于内置肖特基（MnO/Ag）和-结（MnO/SnO）的同时存在以及体系各组分之间的直接化学相互作用，提出了对观察到的行为的一种解释，以讨论观察到的活性增强，这为安全终端用途的气体监测设备的开发铺平了道路。
