Department of Chemistry , Texas A&M University , College Station , Texas 77842-3012 , United States.
Department of Materials Science and Engineering and Research Institute of Advanced Materials (RIAM) , Seoul National University , Seoul 151-744 , Republic of Korea.
ACS Appl Mater Interfaces. 2018 May 2;10(17):14901-14913. doi: 10.1021/acsami.8b02439. Epub 2018 Apr 19.
Multicomponent oxides can be extensively explored as alternative gas-sensing materials to binary oxides with their structural and compositional versatilities. In this work, the gas-sensing properties of CuBiO have been investigated toward various reducing gases (CHOH, NH, H, CO, and HS) and oxidizing gas (NO) for the first time. For this, the powder synthesis has been developed using the polymerized complex method (Pechini method) to obtain a single-phase polycrystalline CuBiO. The defect, optical, and electronic properties in the prepared CuBiO powder were modulated by varying the calcination temperature from 500 to 700 °C. Noticeably, a high concentration of Cu-oxygen vacancy ([Formula: see text]) defect complexes and isolated Cu ion clusters was found in the 500 °C-calcined CuBiO, where they were removed through air calcination at higher temperatures (up to 700 °C) while making the compound more stoichiometric. The change in the intrinsic defect concentration with the calcination temperature led to the variation of the electronic band gap energy and hole concentration in CuBiO with the polaronic hopping conduction (activation energy = 0.43 eV). The CuBiO sensor with 500 °C-calcined powder showed the highest gas responses (specifically, 10.4 toward 1000 ppm CHOH at the operating temperature of 400 °C) with the highest defect concentration. As a result, the gas-sensing characteristics of CuBiO are found to be dominantly affected by the intrinsic defect concentration, which is controlled by the calcination temperature. Toward reducing HS and oxidizing NO gases, the multiple reactions arising simultaneously on the surface of the CuBiO sensor govern its response behavior, depending on the gas concentration and the operating temperature. We believe that this work can be a cornerstone for understanding the effect of chemical defect on the gas-sensing characteristics in multicomponent oxides.
多组分氧化物可以作为替代二元氧化物的广泛探索的气体传感材料，因为它们具有结构和组成的多样性。在这项工作中，首次研究了 CuBiO 对各种还原气体（CHOH、NH3、H2、CO 和 H2S）和氧化气体（NO）的气体传感性能。为此，采用聚合络合法（Pechini 法）开发了粉末合成方法，以获得单相多晶 CuBiO。通过将煅烧温度从 500 至 700°C 来调节制备的 CuBiO 粉末中的缺陷、光学和电子性能。值得注意的是，在 500°C 煅烧的 CuBiO 中发现了高浓度的 Cu-氧空位（[Formula: see text]）缺陷复合物和孤立的 Cu 离子簇，通过在较高温度（高达 700°C）下进行空气煅烧去除了这些复合物，同时使化合物更加化学计量。随着煅烧温度的变化，本征缺陷浓度的变化导致 CuBiO 的电子能带隙能量和空穴浓度发生变化，其通过极化子跳跃传导（激活能 = 0.43 eV）。在 500°C 煅烧的粉末的 CuBiO 传感器显示了最高的气体响应（特别是在 400°C 的工作温度下，1000 ppm CHOH 时为 10.4），具有最高的缺陷浓度。结果表明，CuBiO 的气体传感特性主要受内在缺陷浓度的影响，而内在缺陷浓度又由煅烧温度控制。在同时减少 H2S 和氧化 NO 气体时，CuBiO 传感器表面上同时发生的多个反应决定了其响应行为，这取决于气体浓度和工作温度。我们相信，这项工作可以为理解化学缺陷对多组分氧化物气体传感特性的影响奠定基础。
