Peng Fang, Yu Weiwei, Lu Yue, Sun Yan, Fu Xiuli, Hao Jia Ming, Chen Xin, Cong Rui, Dai Ning
State Key Laboratory of Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083, China.
School of Electronic Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China.
ACS Appl Mater Interfaces. 2020 Sep 16;12(37):41230-41238. doi: 10.1021/acsami.0c09213. Epub 2020 Aug 31.
To verify the effect of oxygen vacancy on gas sensitivity, we have systematically investigated the gas-sensing performance of copper oxide/substoichiometric tungsten oxide (CuO/WO) nanocomposite sensors. Oxygen deficiency in WO facilitates the reaction of hydrogen sulfide (HS) gas with chemisorbed oxygen species (i.e., O, O, and O) at low temperature. The oxygen/sulphur exchange reaction between CuO and HS in the sensing process can achieve room temperature operation of gas sensors. After the WO nanorods were modified by a low content of CuO nanoparticles (Cu:W = 1:20), the sensors present an -type sensing behavior. Their best working temperatures drop from 289 °C (or 386 °C) to 99 °C (or 70 °C) at which the responses are improved by 14 to 163 times for different values. Among them, CuO(L)/WO shows the highest sensitivity of 1575.7 to 10 ppm HS at 99 °C and 171.5 to 10 ppm HS at room temperature. Once WO were loaded with a high concentration of CuO nanoparticles (Cu:W = 1:2), they exhibit a -type behavior, and the optimal working temperatures reduce suddenly to room temperature at which CuO(H)/WO displays the most sensitive response of 7.2 even toward trace amounts of HS as low as 100 ppb. In addition, -type CuO weakens the metal-like characteristics of WO and such weakening effect enhances with an increase in the CuO content. Therefore, the sensing performance of the CuO/WO composite is the best among the four CuO/WO sensors. The two designs for low and high Cu/W molar ratios all achieve enhanced room-temperature HS gas response, with a fast recovery time of ∼60 s under heating pulse, as well as an excellent selectivity, which makes the sensors a promising candidate for practical applications. Moreover, the micro-Raman spectra confirmed CuS formation and the thermal effect on the decomposition of CuS in the sensing process was studied.
为了验证氧空位对气敏性能的影响，我们系统地研究了氧化铜/亚化学计量比氧化钨（CuO/WO）纳米复合传感器的气敏性能。WO中的氧缺陷促进了硫化氢（HS）气体在低温下与化学吸附的氧物种（即O、O和O）的反应。传感过程中CuO与HS之间的氧/硫交换反应可实现气体传感器的室温操作。在用低含量的CuO纳米颗粒（Cu:W = 1:20）修饰WO纳米棒后，传感器呈现n型传感行为。它们的最佳工作温度从289℃（或386℃）降至99℃（或70℃），在该温度下，对于不同的 值，响应提高了14至163倍。其中，CuO(L)/WO在99℃时对10 ppm HS的灵敏度最高，为1575.7，在室温下对10 ppm HS的灵敏度为171.5。一旦WO负载高浓度的CuO纳米颗粒（Cu:W = 1:2），它们呈现p型行为，最佳工作温度突然降至室温，此时CuO(H)/WO即使对低至100 ppb的痕量HS也显示出最灵敏的响应，为7.2。此外，p型CuO削弱了WO的类金属特性，且这种削弱效应随着CuO含量的增加而增强。因此，CuO/WO复合材料的传感性能在四种CuO/WO传感器中最佳。低铜/钨摩尔比和高铜/钨摩尔比的两种设计均实现了增强的室温HS气体响应，在加热脉冲下恢复时间快，约为60 s，以及优异的选择性，这使得该传感器成为实际应用中有前景的候选者。此外，微拉曼光谱证实了CuS的形成，并研究了传感过程中热对CuS分解的影响。
