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Chemoresistive CO2 Gas Sensors Based On La2O2CO3: Sensing Mechanism Insights Provided by Operando Characterization.
ACS Sensors ( IF 8.2 ) Pub Date : 2020-08-04 , DOI: 10.1021/acssensors.0c00882 Takuya Suzuki 1, 2 , Andre Sackmann 1 , Alexandru Oprea 1 , Udo Weimar 1 , Nicolae Bârsan 1
ACS Sensors ( IF 8.2 ) Pub Date : 2020-08-04 , DOI: 10.1021/acssensors.0c00882 Takuya Suzuki 1, 2 , Andre Sackmann 1 , Alexandru Oprea 1 , Udo Weimar 1 , Nicolae Bârsan 1
Affiliation
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Our previous studies demonstrated that rare-earth oxycarbonates Ln2O2CO3 (Ln = La, Nd, and Sm) and rare-earth oxides Ln2O3 (Ln = Nd, Sm, Gd, Dy, Er, and Yb) are sensitive to CO2 and that hexagonal La2O2CO3 is the best among them in terms of sensitivity, stability, and selectivity. In this study, we have conducted a comprehensive operando characterization on a hexagonal La2O2CO3 based sensor for the basic understanding of the sensing mechanism. This was done by performing under actual operating conditions simultaneous DC resistance and work function changes measurements, AC impedance spectroscopy measurements, and simultaneous DC resistance and DRIFT spectroscopy measurements. The results demonstrate that the double Schottky barriers at grain–grain boundaries are dominant contribution to sensor resistance; there is a competitive adsorption between carbonate species and hydroxyl groups, which depends on both CO2 concentration and humidity and leads to the change in height of the Schottky barriers. Finally, we propose a reaction model stating that there are three types of adsorbates, −CO32–, −OH–, and −O2–, and the relative concentration of which is controlled by a reaction with ambient humidity and CO2. This model is able to consistently explain all our experimental findings.
中文翻译：
基于La2O2CO3的化学电阻式CO2气体传感器：Operando表征提供的传感机理见解。
我们以前的研究表明，稀土碳酸盐Ln 2 O 2 CO 3（Ln = La，Nd和Sm）和稀土氧化物Ln 2 O 3（Ln = Nd，Sm，Gd，Dy，Er和Yb）对CO 2敏感，在灵敏度，稳定性和选择性方面，六角形La 2 O 2 CO 3是其中最好的。在这项研究中，我们对六角形的La 2 O 2 CO 3进行了全面的操作表征基于传感器的传感机制的基本了解。这是通过在实际操作条件下同时执行直流电阻和功函数变化测量，交流阻抗谱测量以及直流电阻和DRIFT谱测量来完成的。结果表明，晶粒边界处的双肖特基势垒是传感器电阻的主要贡献。碳酸盐种类和羟基之间存在竞争性吸附，这取决于CO 2浓度和湿度，并导致肖特基势垒高度的变化。最后，我们提出了一个反应模型，指出存在三种类型的吸附物：-CO 3 2 –，- OH –和-O 2–的相对浓度通过与环境湿度和CO 2的反应来控制。该模型能够始终如一地解释我们所有的实验结果。
更新日期：2020-08-28
中文翻译：
基于La2O2CO3的化学电阻式CO2气体传感器：Operando表征提供的传感机理见解。
我们以前的研究表明，稀土碳酸盐Ln 2 O 2 CO 3（Ln = La，Nd和Sm）和稀土氧化物Ln 2 O 3（Ln = Nd，Sm，Gd，Dy，Er和Yb）对CO 2敏感，在灵敏度，稳定性和选择性方面，六角形La 2 O 2 CO 3是其中最好的。在这项研究中，我们对六角形的La 2 O 2 CO 3进行了全面的操作表征基于传感器的传感机制的基本了解。这是通过在实际操作条件下同时执行直流电阻和功函数变化测量，交流阻抗谱测量以及直流电阻和DRIFT谱测量来完成的。结果表明，晶粒边界处的双肖特基势垒是传感器电阻的主要贡献。碳酸盐种类和羟基之间存在竞争性吸附，这取决于CO 2浓度和湿度，并导致肖特基势垒高度的变化。最后，我们提出了一个反应模型，指出存在三种类型的吸附物：-CO 3 2 –，- OH –和-O 2–的相对浓度通过与环境湿度和CO 2的反应来控制。该模型能够始终如一地解释我们所有的实验结果。
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